Welcome to ned Productions

Saturday 5 October 2024: 11:46. In my last post on my house build, I expressed frustration that everything had ground to a halt because everybody takes staggered holidays during August, effectively wiping it out as anybody not on holiday gets blocked by somebody else on holiday. One month later, there has been no further progress still. This got me rather annoyed, my house was clearly getting back burnered behind other people’s projects while we here keep renting – so I had to go make some noise as the squeaky wheel is what gets the oil. But all very annoying, Ireland is now building more houses per capita than anywhere else in Europe and it’s very noticeable how everybody is pegged out. There is no ‘spare slack’ which I’m sure is frustrating for everybody, but well to be blunt I don’t care about other people – where’s my house???

Anyway here’s hoping that by this time next month we’ll be out of structural engineering. Three months for SE is a long time.

As we all sit around waiting, I have been pushing onwards with the future house projects. Last post I mentioned:

1. Implementing the ventilation boost fan per inlet and outlet in the house.

2. 3D printing extensions to an IKEA Fridans blind to avoid the expense of IKEA Fytur blinds.

3. Dimming RGBW LED strips with my ‘new’ IRF540N MOSFET boards.

I haven’t got to item (3), but I’ve made significant progress with (1) and (2). (1) is what I’ll be writing about today.

Ventilation boost fans

Last post I said:

I shall be testing a €4 inc VAT driver based on what Aliexpress claims is a BTS7960 H-bridge. It claims it can handle 43 amps, the reviews are clear it cannot, but it should handle the max 3 amps we’ll ever demand from it. The BTS7960 can take a max 30v, so I’m a little concerned that back EMF from the 24v bilge pump fan might spike over that. However it would seem that these bilge pumps respond very well to lower voltages, they turn well at 5v and have more than plenty flow in my opinion at 12v (and at 24v, they’re insane) so chances are very high I’ll run them at 12v and make everything easier on myself.

And here it is wired up:

The BTS7960 H-bridge is by far the cheapest ‘not small’ motor driver on Aliexpress. I had been a little worried about it, but having tested it myself and watched plenty of YouTube videos of other people testing it (including to destruction), I’m feeling much happier with it. The BTS7960 ICs themselves (assuming they aren’t fake clones) claim a max 43 amps, but they’ll throw out an enormous amount of heat for that and besides the cheap module these are mounted on doesn’t have thick enough traces to handle such current. YouTube reviews reckon the safe maximum without active cooling is about 15 amps, and moving the heatsink from the ‘wrong’ side to the front also helps.

There isn’t much to the ESPHome scripting for this – you put a PWM onto the forward and backwards pins, and a digital output onto the forwards and backwards enable. Enabling both backwards and forwards shorts the windings, which equals braking now as the back EMF from the motor stops the turn quicker than preventing the back EMF flowing. The BTS7960 is happy with 3.3v TTL and at the currents that the ESP32 outputs, so it ‘just works’:

The first thing you may notice in the video is coil whine – for some reason I don’t remember now, I had configured the PWM for these to 3662 Hz so unsurprisingly, there is a clear 3662 Hz tone in the video. I think I might have done that to reduce the impact of voltage spikes from back EMF on the electronics, but if I’m now running at 12v which I think I am (as you can see, they still go like the clappers despite being 24v motors), then something much higher frequency would make sense. The ESP32 has a 80 Mhz base frequency for its PWM, so the obvious choice would be 625 kHz to give 128 steps. However the datasheet for the BTS7960 says 25 kHz is the maximum, so 2048 or 4096 steps seem like reasonable choices and nobody will be hearing 20 kHz whine.

The second thing you may notice if you have a HDR display is that the above video ‘glows’ brightly compared to the rest of the page. This is because it is in HDR10+! What won’t be so obvious is that it’s the first ever AV1 encoded video on this website, and I encoded it at 1080p Full HD in ten bit HDR with stereo AAC audio with a capped bitrate of 500 Kb/sec. That entire minute long video is only 3.8 Mb long! Two hours of it would be 456 Mb.

I think you’ll agree that it came out very well for such a low bitrate, so I expect to be mounting all future videos directly on this website instead of having YouTube host them. I only have seven videos on YouTube, so there’s even an argument of converting the lot down to be direct. I had only ever mounted two videos directly to this site before, both reduced severely in resolution to keep the file small, but if AV1 can encode 1080p Full HD in HDR10+ at that kind of quality for that low file size I think that’s the future. What I’m still wrapping my head around a little is that twenty five years ago, ninety minute movies came in a 700 Mb file to fit on a CD. For that you might have gotten 720 x 340 resolution encoded in MPEG-4 with MP3 encoded audio. Here we are in 2024 with 8.5x more resolution and Rec.2020 colour gamut in half the bitrate. It’s impressive.

My phone which took the video remains the venerable Samsung Galaxy S10 from 2019. I’ve never owned a phone past two years until this phone, and here it is still going strong into its fifth year (batteries clearly took a huge leap forwards around then). Mine runs Android 11, mainly because I keep thinking it isn’t worth upgrading to Android 12 as surely at some point ‘soon’ I’ll be replacing it. Amazingly, you need Android 14 to take photos which retain the HDR information in the file – despite that as early as Android 10 you could happily take HDR video if the hardware was capable. It’s one of those things you’d have thought very easy to implement much sooner, but apparently not.

Anyway I think that’s the first half of the ventilation boost fan problem solved – it goes forwards and backwards at any speed you like under ESP32 control. There is more though: how do we decide by how much to reverse the fan to stop the flow i.e. how do we detect air flow direction and dynamically adjust the fan reverse to keep air flow stopped?

Detecting ventilation air flow (cheaply!)

I’ve sized the ventilation ducts in the house for a linear pressure loss of 0.5 - 1 Pa per metre, so if we want to cut off air in one part of the house (by turning its boost fans into reverse) to boost heating or cooling in another part of the house (by turning its boost fans forwards), we have some slack in the ducts to drive boosted flow in that direction. The Zehnder ComfoAir Q600 data sheet says it should not have more than 200 Pa pressure at the unit for a long service life, so we will need to balance the speed of the fans to ensure no excessive loads anywhere in the system. For this, ideally speaking, you’d fit air velocity meters at every ventilation inlet and outlet.

The FS3000 sensor is exactly what one would prefer – it has two models, one can measure up to 7.23 metres/sec and the other up to 15 metres/sec. The worst case air velocity in this system is the 180 mm diameter connection at the MVHR unit which is 6.52 metres/sec, so the first model would be the right one. Unfortunately, the FS3000 sensor it is expensive – cheapest I can find it is €55 inc VAT delivered each. I have seven boosted stale air outlets and eight boosted fresh air inlets, so that would cost me €825 inc VAT which is a bit much. Can I do it cheaper?

A Mass Air Flow Sensor like cars use are much cheaper, but as they work by measuring the resistance of a heated wire in the airflow, they are non-linear temperature sensitive and my fresh air outlets will have varying temperatures, so that won’t work. What I really need is something solid state, and temperature insensitive.

I had a few spare BME280 temp + press + humidity sensors, so I tried sellotaping one onto the fan and see what readings it gets:

In the video I ran the fan both forwards and backwards (you might have noticed I fixed the audible coil whine since) and I found these readings:

Backwards 100%	Backwards 50%	Stopped 1	Stopped 2	Forwards 50%	Forwards 100%
100048.599 Pa	100044.02 Pa	100032.2068 Pa	100038.2385 Pa	100032.901 Pa	100016.3545 Pa
0.0164%	0.0058%	0%	0%	-0.0053%	-0.0158%

The difference between the two stopped values is 0.006%, and that especially clarifies the problem here – yes the BME280 can tell if there is air flow or not (+/- 16 Pa for 100% speed), but due to the drift in the absolute reading over even short periods of time, it won’t be useful for this application.

What I actually need here is a differential pressure sensor which returns the difference between two inputs (here: inside the duct and outside the duct), but the cheapest one of those I can find is €45 inc VAT so not much better than the FS3000 air velocity sensor. So let’s see if there are better barometic sensors for a reasonable price:

	Noise	Relative accuracy	Absolute accuracy	Cost incl delivery
BMP280	3 Pa	+/- 12 Pa	+/- 100 Pa	€0.56
BMP390	2 Pa	+/- 3 Pa	+/- 50 Pa	€4
BMP581	0.1 Pa	+/- 6 Pa	+/- 50 Pa	€53

The improvement in relative accuracy of the BMP390 would be a large help, but that +/- 50 Pa in absolute accuracy is a problem. In atmospheric pressure terms, it’s the difference between 1000 hPa and 1000.5 hPa, so very accurate on that scale which is what it was designed for. But not ideal for my purposes where my max pressure difference will be around 16 Pa.

In any case, I reckon it’s worth a punt on getting some of the BMP390s and seeing what they’re like, so I ordered three. Should arrive within a month.

Olimex ESP32-PoE detailed power consumption

Believe it or not, it’s almost exactly two years ago I first mentioned my Olimex ESP32-PoE boards where I described what was known at the time about its power consumption gleaned off datasheets and the internet:

The ESP32 running full belt minus wifi at 240 Mhz will consume about 50 mA, peripherals can’t draw more than 250 mA if on PoE, and perhaps less than that if on battery. An idling ESP32 might draw 4 mA, therefore a 3000 mAh battery could run the device for between 30 and 750 hours (one month) assuming board power overhead of 20-50 mA. If you can put the device into deep sleep, that draws only 0.1 mA, which could be up to 30,000 hours (or over three years)!

and:

Thanks to this being an open source hardware design, I discovered that the DC-DC stepdown chip is the TX4138 whose datasheet can be found at https://datasheet.lcsc.com/lcsc/1811141153_XDS-TX4138_C329267.pdf. It claims an 84% efficiency. Assuming it’s a linear regulator taking the 5v to 3.3v and therefore burns as heat 33% of the current the ESP32 uses, a 100 mA draw by the ESP32 at 3.3v (one third of a watt) would be 133 mA of 5v, or two thirds of a watt. That turns into a minimum of 0.8 watts of PoE power, which is a best case efficiency of 41%.

By the way, that test board measuring CO2, humidity etc shown in that post two years ago has been running continuously since then with zero issue. Its OLED display now suffers from burn-in, but it’s still going and I have two years of sensor measurements in the database.

Anyway, in the past two years more information has appeared on the internet about these boards, and there is a suggestion that the PoE power consumption can be greatly reduced by removing a resistor on the board. I also needed detailed empirical power consumption metrics in order to figure out whether these boards could drive the blind motor directly without additional power i.e. how powerful a blind motor can I fit without browning out the board when powered off PoE?

You can get a USB power meter easily enough, though the cheaper ones return inaccurate values so shop carefully. Mine is a bit more expensive, but it’s accurate. Finding a PoE power meter turns out to be rather harder – they exist, but cost over €100. And you can get a managed PoE switch for that money, and if you choose the right model it will publish in SNMP the PoE power drawn per port. So I splurged on a TP-Link TL-SG2210P which is the cheapest modern (i.e. 54v based not 48v based) PoE managed switch I could find on the market and I finally have empirical PoE power consumption measurements for the Olimex ESP32-PoE:

	USB (5.2v)	PoE (52.6v) unmodified	PoE (52.6v) with R42 resistor removed
Deep sleep (two LEDs shining)	2 mW	579 mW	switch cuts power, so must be < 500 mW
Idle in ESPHome no ethernet (two LEDs shining)	386 mW	n/a	n/a
As above with ESPHome trying to get ethernet	454 mW	n/a	n/a
Idle in ESPHome with ethernet (four LEDs shining)	553 mW	1525 mW	947 mW
Idle as above with all peripherals for a bedroom	600 mW	1736 mW	1158 mW (estimated)

One of the first things you notice is how power expensive an active Ethernet connection is. It was designed in the days before low power unfortunately, and a 100 Mbit connection will gladly consume ~110 mW with gigabit and higher sucking down ~400 mW upwards just for idle. It goes even higher if data is moving, but these boards will mostly be silent.

In terms of thermal camera heating after being left in free air for twenty minutes:

Back and front of board when in deep sleep powered by PoE with R42 resistor present. Note that hottest spot (54.5 C) is the R42 resistor on the back

Back and front of board when running powered by PoE with R42 resistor present. Note that hottest spot (70.7 C) is still the R42 resistor on the back, and the overall board is 52 C

Back and front of board when running powered by PoE with R42 resistor removed. Note that the overall board has dropped to 38 C now the 0.5 watts of additional heating has been removed

To be honest, I was a little shocked at how high both the thermal heating and the PoE power consumption is. I had been assuming ~1 watt for an empty board off PoE. I was out by 50%, which adds up if you fit lots of boards. Add some peripherals – in this case, 2x 5v <=> 3.3v level shifters, a BME280 temperature, humidity and pressure sensor, and the rotary encoder on the GA12-N20 motor – and you’re burning ~1.75 watts per board. If I fit thirty of these boards, that’s 52 watts of heat being pumped into the house. To put that into context, my entire 3000 litre thermal store in summer leaks ~60 watts into the house. Adding another fifty watts of background heating puts into jeopardy no overheating of this house in summer!

Removing resistor R42 which burns 500 mW to keep the PoE supply going is an obvious step, but I think we can do better than 1.2 watts idling with that resistor removed for not much extra money. PoE doesn’t actually require a constant 500 mW of load to stay active – rather it needs to see 500 mW of load for at least 60 milliseconds every 340 milliseconds. This is a duty cycle of 15% on a tick of 400 milliseconds, reducing amortised load to keep PoE active to 75 mW. If I could get these boards mostly into deep sleep, and have some sort of pulse generator generate load at the right duty cycle, that could reduce heat contributed to the house significantly.

My first instinct was a 555 pulse timer circuit which are cheap and plentiful at €0.58 inc VAT delivered each, however it turns out when they’re off they consume ~425 mW which seems like we could do better. After quite a bit of research I landed on a surprising conclusion: the most cost effective way of implementing a low power pulse generator is actually a second ESP32 chip which does nothing but deep sleep for 340 ms and power on for 60 ms. This seems wasteful for a microcontroller as powerful as an Intel Pentium II from 1997, but the economics are what they are – I can get an ESP32-C3 on a breakout board with USB-C, onboard programmer and 3.3v buck converter delivered for €1.50 inc VAT! Madness! And it doubles as ‘the load’ because you can turn on the Bluetooth and Wifi stacks to consume up to 200 mW @ 3.3v (which should be just enough to consume 500 mW @ PoE), whereas the 555 circuit would need an additional load resistor and wiring. Assuming that the 2 mW deep sleep is the same for both, and conversion losses might be 5x at such a low current, it might draw 25 mW from PoE during the off cycle. That should bring total PoE draw to under 100 mW per device amortised, so under three watts for the total. Which is better than 52 watts!

In case you’re wondering why not use the existing ESP32 for this, one could theoretically modify ESPHome to do this for you. However, it would be a lot of work – the ESP32 has a bootloader stage and a main stage, and it takes 100 milliseconds to reach the main stage. So to get the timings we need, the firmware must exclusively operate within the bootloader stage. That’s deep customisation of ESPHome, and to be honest for €1.50 I can make the problem go away so a second ESP32 it is.

The ESP32-C3 boards are on their way from Aliexpress and when they arrive they surely will be written about here. Watch this space!

If I were starting all this again – and it wasn’t obvious at all at the beginning nor was it available until recently – Olimex now have a v2 of the ESP32-POE which can draw 25 watts instead of 12.5 watts from PoE, and has a built-in 12v 1.5 amp supply. That bilge fan if running off 12v should consume less than that though it would need a slow start implementing to prevent brown out. I’ve already bought the PoE switches etc and they were all sized for max 12.5 watts per port, so that ship has sailed. Still, if you’re reading this thinking about replicating what I’ve done, it’s worth bearing in mind.

Next post I might – or might not – cover the blind automation or the LED strips or the ESP32-C3 boards. We shall see how things go. I kinda do want a video of a real blind going upwards and downwards on command and demonstrating that when it gets to the top, it stops on its own. I have some 3D printing between now and then to reach that, not least because my initial 3D print of the blind spool ended up losing its grip on the motor because the motor’s torque is so strong and its burred the plastic, despite that being ABS. So I had to go get little metal cogs for the end of the motor and I’ll need to redesign the blind spool to fit the metal cog.

Still, what else do I have to be doing? At least this advances the house build in its own way.

#house #esp32-poe

Saturday 24 August 2024: 11:54. Two months since the last post on my house build. Obviously last post when I said:

I expect getting the GA and Structural Engineering (SE) drawings to final sign off will consume a great deal of my free time next few weeks. I also will need to start various balls rolling in terms of getting workers and supplies and indeed the mortgage in place by the various due dates. A long eighteen months beckons before us.

I jinxed myself. Silly Niall.

What the first draft of the GA drawings did enable in the past two months is a first draft of the SE drawings, and then everything went on pause because obviously everybody goes on summer holidays apart from us. I expect nothing further to happen until at least September.

This pushes back the likely erection of the timber frame to Spring 2025. This is disappointing. Anyway, here are the draft GA and SE floor plans for your entertainment:

There isn’t a huge amount to say about these, they are pretty much what the architect’s drawings had, and what deviations there have been I’ve since had undone in feedback. I suppose it is interesting that the most pressing weight in the entire building will be between his and hers bathroom sinks in the master bedroom ensuite.

Despite the further slippage to the build date, I suppose there is at least forward progress. Got to look at the sunny side I suppose.

Before I do my usual show and tell of projects I’ve been working on this past two months, I suppose I ought to mention that an epoch has come to a close. Approximately twenty-four years ago while I was living in Madrid, Spain I subscribed to my first Boost C++ libraries mailing list. That was the first step in what became a long road culminating in me digging real deep to get Boost.Outcome past peer review and into the Boost C++ Libraries in 2019. That, in turn, approximately doubled my earning power for my next role and doubled it again for my following role. Without getting that library past peer review and into Boost, I think it safe to say that I could never have afforded to leave renting and get my own home.

However, I think it’s now time to move on from the Boost C++ Libraries so I won’t be participating there going forth apart from continuing to sustain Outcome i.e. I’ve unsubscribed from everything there, and I no longer consider myself having anything to do with Boost going forth.

Casting to a wider picture, I’m also winding down my C++ participation in general. Serving at WG21 has broken me to be honest, it’s increasingly ‘anything but C++’ for me which is a shame, as it isn’t the language’s fault. I expect that the Sofia meeting in Summer 2025 will be my last face to face meeting, thereafter I’ll attend virtually only. I have ceased progressing all my WG21 papers apart from P1030 std::filesystem::path_view, and assuming that makes it in before the C++ 26 IS major feature deadline (yes, you guessed it, Summer 2025), that will be the only evidence of seven years of my service at WG21.

I am not remotely alone in moving on – WG21 broke a whole generation of us with our ideas about getting good engineering achieved. A good portion of my generation of C++ programmer at Boost and at WG21 will in fact be moving on like me. It’s funny you know, wind me back twelve years ago and I couldn’t really understand why people moved on as a whole bunch just had after C++ 11 had shipped, but now that C++ 26 will ship soon yeah I totally get it now. The standards process just chews you up if you try to change anything which matters. And then you find yourself asking why am I bothering with all this if it isn’t pleasant, doesn’t benefit me, and I don’t get paid for it?

As you might gather, I’m on the hunt for a new programming language to dig into, one without the baggage and dysfunctionality of C++. I haven’t seen one yet, but I’m hoping a true C++ successor might turn up soon (and no, Rust isn’t that). To preempt people emailing me with their pet languages, this is what I seek from a true C++ successor:

1. SIMD orientated, not scalar orientated.
2. Stack unwinding resource release.
3. Functions default to doing only static memory allocation like for embedded toolchains (i.e. where the linker can precalculate all allocations and reserve space for them at link time), otherwise you are required to supply memory from outside. A function can opt out of this so it can use unbounded dynamic memory allocations, but then only ‘non-deterministic’ functions like it may call it.
4. Same as the above, but for thread synchronisation.
5. Borrow checker, but not annoying and productivity damaging like Rust’s.
6. Superb compatibility with at least two existing major language ecosystems so it isn’t a pain to bridge in existing codebases.

The closest that I am currently aware of is Mojo, but the syntax is too scalar and Python-like for me personally. What I’d really prefer is a syntax which encourages you to write in SIMD friendly terms to the maximum extent possible.

Until my shining knight in systems programming language armour turns up, I intend to move over to WG14 the C programming language where I hope to get modernised signal handling into C, and thence into absolutely everything else. It should keep me busy for a good few more years yet. And I probably will do a circuit of the global C++ conferences as a good bye swan song, say good bye to lots of people, tie everything up nicely.

Taught myself further how to design 3D printable things

As I was looking after my children during my mornings before work throughout these past two months, my productivity has been quite impaired compared to normal. Still, I bit the bullet and invested several more very late evenings these past two months into learning how to design things which can be 3D printed, building on my experience gained in designing the picture frame shown in the last post. I went at things again in MeshMixer and I yielded this by early July:

This is my ‘midi’ case for my Olimex ESP32-POE boards which I’ll be fitting throughout my house (you can find its Thingiverse page here). The midi case can take up to a 3400 mAh battery and an additional breakout board which almost certainly will be an Olimex UEXT extender for my use cases. This is the first thing I ever printed in ABS on my Anycubic Kobra Go 3D printer, and I can testify getting a successful print is indeed a black art on this printer, which isn’t really designed for ABS printing. My printer has a Bowden drive, which pushes and pulls the filament far from the hotend. This introduces ‘bounce’ into retraction cycle, which means filament is left in the hot end, and ABS it tends to singe which then means it clogs and then flow stops. Or if the hotend is too close to the print surface, it can’t extrude quickly enough so it singes and it clogs. Or if the wind is blowing slightly wrong, it singes and blocks. Painful.

As we saw in the commercial print of the house model with a Prusa XL, a direct drive hotend has no such troubles with ABS. But that’s a far more expensive printer than mine, and maybe by varying ABS filament I might find one less finickety than my current ABS filament in my cheap printer.

After the midi case, there was an obvious ‘mini’ case waiting to be extracted:

And then a maxi case, though it has design quirks I’d like to change about it so I haven’t uploaded it to Thingiverse yet:

My maxi case is currently wired up as a prototype for a bedroom in the future house. All available i/o bar one input is fully loaded:

• GPI34 (PINS) is unused (is always pulled up)
• GPI35 (PINS) is wall dimmer switch level shifted down to TTL
• GPI39 (PINS) is external power supply voltage (analogue)
  
  
• GPIO13 (UEXT) is I2C-SDA for sensors
• GPIO16 (UEXT) is I2C-SCL for sensors
  
  
• GPIO4 (PINS) is blind motor sensor A
• GPI36 (UEXT) is blind motor sensor B
• GPIO0 (PINS) is blind motor PWM forwards
• GPIO1 (PINS) is blind motor PWM backwards
  
  
• GPIO2 (UEXT) is LED strip colour R
• GPIO5 (UEXT) is LED strip colour G
• GPIO14 (UEXT) is LED strip colour B
• GPIO15 (PINS) is LED strip colour WW
  
  
• GPIO3 (PINS) is ventilation fan driver enable
• GPIO32 (PINS) is ventilation fan forwards
• GPIO33 (PINS) is ventilation fan backwards

Chances are high that LED strip pins R, G and B won’t be wired in in most rooms as those only have warm white downlighters. In fact, chances are high that initially I won’t wire the lighting into the ESP32 boards at all, as it’ll save me time.

The ventilation fan drive I haven’t tested yet, but I shall be testing a €4 inc VAT driver based on what Aliexpress claims is a BTS7960 H-bridge. It claims it can handle 43 amps, the reviews are clear it cannot, but it should handle the max 3 amps we’ll ever demand from it. The BTS7960 can take a max 30v, so I’m a little concerned that back EMF from the 24v bilge pump fan might spike over that. However it would seem that these bilge pumps respond very well to lower voltages, they turn well at 5v and have more than plenty flow in my opinion at 12v (and at 24v, they’re insane) so chances are very high I’ll run them at 12v and make everything easier on myself.

Something a bit mad to consider is that my fresh air ventilation pipes will need 50 mm of insulation each side, so a 100 mm diameter pipe will become 200 mm. The above bilge pump takes a 100 mm pipe, it itself is 135 mm, so it’ll be entirely encased within the insulation and apart from some wires sticking out you’ll never know it was in there. I’m hoping that the motor will tolerate the ~60 C air temperatures, as a bilge pump it should. The plastic is ABS, so should be absolutely fine at 60 C.

You’re likely going to be very curious about the blind motor. This is my solution to paying a lot of money for IKEA Fytur blinds, instead I’m going to motorise a very cheap IKEA Fridans blind using ABS printed parts and a carefully chosen GA12 N20 geared motor with rotation encoder costing €7 inc VAT which is small enough to fit inside the blind’s roller. I won’t say much more about it this post other than I’ve successfully got it to turn from the ESP32 using only the available 5v amperage from the PoE supply without seeing power brownouts, and I can testify it has quite considerable torque and should be able to lift quite a lot of blind. What I haven’t got working yet is getting ESPHome to detect when the motor has stopped turning, and to turn off the power. Free time will fix that, as always.

House model display case

The custom made cases for the commercially printed house model arrived and for the money, they are excellent:

The acrylic upper is fully bonded and forms a single surface. The base of the large model has mahogony laminate strips, while the base of the small model is black acrylic. Including delivery, for under £200 inc VAT. The supplier’s name is LasAcryl Ltd, they’re actually French but of course their English website thinks the only possible currency is Sterling.

The extra height of the case will be used by standing each layer of the house on stilts, with little LED panels inside lighting the house. You’ll thus be able to see all around the inside of the model house whilst standing instead the actual finished house. It may well be a decade before I get to assemble all the parts to create the final display case, or if this build takes even longer I might just get it done before the build starts. We’ll see.

House dashboards, revisited

Last post I mentioned that I didn’t like the e-Ink displays for the future house dashboards, and for £115 inc VAT you could get a portable touchscreen monitor off Amazon. Well, I went ahead and bought one for £98 inc VAT instead:

Apologies for the stock image, it’s because the actual device is already out at the site configured as the TV for the children to watch when we’re out there using the old TV box, old TV remote control and some very old computer speakers (y’see, this is why one should never ever throw anything out!).

And well, for the money, I am impressed! The PoE powered Raspberry Pi Zero 2 described last post will power it without issue (albeit with a bit of tweaking to overdrive the HDMI signals on the Pi). The touchscreen works great and the Pi recognises it. I can display interactive graphs which respond to touch – it ain’t quick because the Pi chugs a bit when rendering 1080p, but it is absolutely functional.

In terms of the device itself, it is surprisingly good for the money. The display isn’t bright, but given that it works from USB power alone and illuminates 15.6 inches, I think it’s as good as is feasible for the five watts available to it or so. As it’s an IPS panel, colour reproduction is very good apart from magenta tending to pink. The 1080p resolution is plenty for this size. Using this display indoors if it’s bright sunshine outside is just about okay, if it’s cloudy outside then it’s plenty bright enough indoors. Its speakers are absolute crap, barely any volume out of them, but I have my old computer speakers for that and it does have a headphone jack. It has half a 75 mm VESA mount on the back, and I’ve already affixed that to a cheap monitor arm, later it will get mounted on the wall in the kitchen.

Oh and there’s one more kicker – yes it responds to VESA brightness commands, so you can dim it and brighten it arbitrarily. If combined with a Time of Flight sensor to detect local motion, you can wake the display if somebody goes near it. Very nice.

What comes next

Many moons ago after testing IRF520N MOSFET based solutions for dimming LED strips, I realise that I had bought poorly and I should have bought IRF540N MOSFETs instead as they should run much cooler. Easily two years ago now I did buy a bunch of four channel IRF540N MOSFET boards, but I’ve never tested them in action. I’d like to get that done, to create peace of mind that this solution will definitely work if asked and they do run cool as the maths had predicted.

I’d like to get that BTS7960 driver tested with my bilge fan at 12v to make sure it definitely works as expected.

And finally, I’d like to get a reference house bedroom ESPHome firmware written and debugged, which includes window blind control.

If I get all those done, I’m sure a further post will appear here. And god help us if the GA and SE designs get finalised as I might actually finally have to pay for some timber frames!

#house

Sunday 30 June 2024: 22:05. On Friday afternoon the first draft of General Arrangement (GA) drawings arrived from our Timber Frame Supplier. This finally means forward progression in my house build! This starts the clock at long last, and the Gantt chart for all the pieces of the puzzle can finally be shown with some expectation of accuracy:

You will need to click and zoom in on that to make it readable, however upshot is that assuming no unpleasant surprises and that there is sufficient cash flow to maximally parallelise jobs, the outer walls should be up by the start of February 2025 and it would be complete enough to move in before April 2025. The former I think possibly achievable, the latter I do not as I think cash flow will become a serious issue around then especially as we cannot connect sewerage until the outhouse foundations and walls are erected as a minimum. The building will be weather proof, so it now becomes a question of time. We shall cross that bridge when we come to it.

I expect getting the GA and Structural Engineering (SE) drawings to final sign off will consume a great deal of my free time next few weeks. I also will need to start various balls rolling in terms of getting workers and supplies and indeed the mortgage in place by the various due dates. A long eighteen months beckons before us.

Anyway, on a lighter note, the last four weeks saw me continue to horse through backlogged todo items. All sorts of things the parts for which had been bought, tested to make sure they worked and then shelved until more free time appeared have seen completion. Some of these backlogged items were as much as two years old!

9.5v DC power supply fan fix

The first thing I got done wasn’t actually backlogged, but it did take six months to complete as my first approach to doing it didn’t work out, so I had to wait for a second round of parts from Aliexpress. You may remember from last year that the downlights in the house will run from a 9.5v DC power supply, as that had been empirically tested to produce far less heat which will greatly lengthen the lifetime of those very cheap bulbs. It made no sense to downconvert that from the 54v DC mains, it isn’t as efficient as a dedicated three phase to DC power converter. As I only needed a few hundred watts, you can’t actually get three phase AC input supplies for such a low wattage, but you can get two phase supplies. This is one such also from Aliexpress:

As you can see, I have attached an additional board using twine . I’ve been generally impressed with the power supplies I’ve received off Aliexpress, for one quarter the cost of a European made power supply they’re worth buying two of them as a backup and you still save half the cost overall. The build quality isn’t quite to European levels, but at one half the cost with a redundancy, that’s very acceptable. And it’s not like the build quality is bad, not at all, it’s just they cut corners on little things to get the cost down such as in this case, the cooling fan which goes at 100% all the time. To fix this, I added via twine a PWM fan controller and replaced the fan with a variable speed one, total cost under €20 including delivery. And it works a treat, the fan spins slowly at low loads and spins up nicely as the power supply’s heatsink passes 40 C. The conversion efficiency on this one appears to be not as good as the big 54v power supply, I make it around 80-85%, whereas the big supply definitely hits 90% efficient despite me loading it by only five percent. I assume the two phase input is naturally less power efficient than three phase. Still, for the money and given my electricity will always be free of cost, I don’t really care.

(I originally thought that the fan controller could PWM a dumb fan, but it turns out it doesn’t have the resolution nor the smarts, which the Chinglish item description did not make clear. In the end, there was no rush on this and I could afford to wait six more weeks for the right kind of replacement fan).

100w vaulted ceiling floodlights

In the lighting plan, we need to provide a baseline lighting of the ceiling, which is a large volume of space. Said plan envisaged two 100w 3000K industrial flood lights and two 100w 4000K industrial flood lights, each individually switchable. You could thus have daylight, warm white, middle road between the two in four possible brightnesses.

The 4000K colour temperature of the 100w floodlight is rarely in stock, so when it came into stock I snapped up two as they are hard to find otherwise. The 200w model gets up to 67 C which had worried me for indoor use, thankfully the 100w models are much tamer despite having much smaller heatsinks:

56 C I think will do just fine. These flood lights have a double duty, they will be put onto long extension cables so they are highly mobile around the inside of the house after the frames are erected. You can thus position them wherever you need them to be which will be a real boon for working inside the house during winter. Once the inside wiring gets done, they’ll get mounted into their final places.

Commercially printed house model

Last month I mentioned that I had sent off my house model to be printed commercially by a Prusa XL in ABS at 1:62 scale. There was a problem – the roof printed poorly on my printer, but disasterously on their much higher resolution printer. They very kindly allowed me to manually remesh the roof and send the fixed top part. The results came out lovely:

This was printed to the maximum that the Prusa XL can do, 320 mm width using ivory coloured ASA plastic. It came out really nice, the added detail is amazing. I have yet to remove the supports using a sharp knife, I am somewhat not in a hurry because I need to retain the removed plastic to create a ‘plastic slurry’ by dissolving it in acetone. It’s certainly a weekend of work, and I think I’d prefer to do that all at once in a single shot.

I have ordered from Aliexpress LED panels so the inside can be illuminated, and I intend to mount the three parts vertically separated using transparent cake stands. The entire lot will go inside a custom made display case, which I have ordered after much humming and hawing about which online vendor to choose. I expect to mount it in the house where I will be mounting the plans, the history of the evolution of the design, and so on.

When all the bits arrive, if a weekend of time appears, I’ll get it all cut out, slurry paste applied where it is needed, wired up and mounted and then put away into storage. Or, I might kick it into the long touch as well and not get back to it for two years. Depends on what the next eighteen months will be like.

Network connected 3D printer

I keep mentioned the two years ago thing because when I bought my Anycubic Kobra Go 3D printer two years ago, my original intent was to connect it to Wifi via a dedicated Raspberry Pi so it could be operated and monitored remotely using my phone rather than me having to physically go check it every few hours to make sure nothing has gone wrong. I bought all the parts at the time including the then very scarce Raspberry Pi Model 3A+, but never got back to it.

Well now not only did I get back to it, but I completed it! Here is my new setup:

As 3D printers can catch fire and they produce fumes and this one is living in the garage which is full of dirt and insects and cold, I placed the printer inside a fireproof enclosure from the beginning. I had bought an oversized one to fit a filament heater, as southern Ireland is a very damp place and without heating the filament to dry it out first you will not get much printing done successfully. Between the filament heater and the printer, if the lid is closed it gets quite toasty in there, which is a very good thing to avoid curling and bed and layer separation in your prints. Print results, as you have seen, have been very good for such a cheap printer.

For PLA and PETG, by the time upper layers get printed where the enclosure temperature matters for those materials, it will have warmed up. For ABS and ASA you need the enclosure to be fully warmed before printing begins, otherwise your print will not go well. This creates a chicken and egg problem – you can’t start the print without opening the enclosure and letting out the heat. Unless you network it so it can be operated remotely.

The 3D printing hobby community have had for many years a solution to this, it is a dedicated custom edition of Raspbian for Raspberry Pis called Octoprint. You 3D print a case with integrated camera mount using a cheap and nasty IR cut camera, and you need to wire a special USB cable with the 5v line disabled otherwise it won’t be reliable due to bad power supply interactions between the Pi and the printer electronics. You may also notice the BME280 temperature and humidity sensor hanging out the top of the Pi to measure the enclosure’s environment:

2.4 Ghz Wifi reaches into my garage sufficient for the Pi’s embedded antenna just fine, so this works very well. You can remotely watch the camera in pitch dark thanks to the IR lighting, send it stuff to print remotely, and otherwise command and control and monitor all its sensors and progress. I printed its case in PETG, this made snapping it together a bit of a pain, but PETG doesn’t get soft with temperature as easily as PLA so it had to be done. If the enclosure gets up past 40 C, with the camera and Pi adding maybe 15 C to that next to the plastic, PLA I think would sag.

I haven’t tried an ABS print yet using the new setup. I do know what I intend to print, but until the other parts of that arrive from Aliexpress it can wait. In any case, I now can theoretically actually print ABS parts at long last, which was a showstopper for another house related project I’ll describe in a later post if it works out.

House dashboards

As you will remember from past posts which decided this, the house’s automations are based on the Olimex PoE ESP32 board of which I bought fifty. These are great and have proven very reliable, I have one in continuous service as a test and it has been faithfully capturing CO2, temperature, humidity, pressure and air quality every ten minutes and logging them to a network database and showing the numbers on an attached OLED panel. It’s been doing that without break for two years, and has been utterly trouble free. Well, the OLED panel is losing brightness, so I won’t be using more of those in the future, but the board and sensors have been working very well.

As much as the ESP32 is great, it has limited capabilities to drive a display, especially my older ‘WROOM’ edition which unlike the ‘WROVER’ edition it lacks external PSRAM. Due to its slow onboard RAM and that its fastest interface its SPI bus can’t be driven much past 50 Mhz, any attached display maxes out at around 320 x 240. That’s fine for small local displays, but not useful for dashboards you’d want to notice from afar if something is going wrong e.g. thermal store is low on hot water.

I happened to come across on HackerNews that you can now get six colour e-paper for a reasonable price. These displays have the big advantage of costing zero power if they are not being changed, and I was curious to see if they might be suitable for my dashboards as the black and white ones traditionally available didn’t have any way to signal ‘attention’ via colour. I thus bought from Waveshare a 7.3 inch six colour e-paper display for €86 inc VAT, which was as much as I was willing to punt on a test. They have much bigger displays, but those cost a lot more.

While I was on the Waveshare website I noticed that (a) they would sell me multiple Raspberry Pi Zero 2’s in a single order, as many as I would like and (b) they had a reasonably priced PoE hat and case for the Zero. So I ordered four of those, taking advantage of the volume discount and once assembled they look like this:

The sellotape is to keep the lid on, as it isn’t tightly fitting. But yeah, all the ports of the Pi Zero 2 exposed, with four additional USB ports, and a 100 Mbit PoE ethernet, with case for €57.50 inc VAT each. This isn’t exactly cheap, about double my cost estimates from three years ago for a Pi based PoE powered solution. However (i) this is a Pi Zero 2 not a Pi Zero (ii) Pis don’t cost €5 anymore from anywhere, these were in fact €26 inc VAT each (iii) the PoE circuitry here is ‘proper’ and not cheap and based on an inefficient linear converter like the Olimex boards (iv) there has been a good +25% price inflation in general terms since that post three years ago. This explains the doubling of cost, as much as none of us will like it.

They definitely have a switching power converter in their PoE circuits:

46 C is as hot as I could make the overall assembly – the Pi Zero 2 going full belt draws maybe 3.3 watts according to https://www.cnx-software.com/2021/12/09/raspberry-pi-zero-2-w-power-consumption/. I probably didn’t have it drawing that much from the SoC, but I did add a bit of load on USB. Waveshare claim their PoE circuit can sustain 12.5 watts which is the bottom grade of PoE, and I didn’t test more than maybe 5 watts. But I would be surprised if the temperature got much past 65 C even at full load. Unlike the Olimex board’s cheap linear converter, this one appears to be switched, with three hefty large capacitors to smooth out the buck converter. I guess you get what you pay for in this stuff, though not always as my review of PoE ESP32 boards a few years ago showed – boards costing more than this still had crap PoE circuits, so it’s nice to see Waveshare didn’t skimp here.

As much as this is qualitatively better it is obviously still four times more than the €15 inc VAT per PoE ESP32 board (and I exclude the sdcard, which takes it up to just over €60 inc VAT per Pi), however I don’t expect to need many of these in the house, in fact I think three is likely plenty with the fourth as the spare. And unlike the ESP32s, these can drive big displays, up to 1440p over HDMI albeit at a reduced refresh rate. You do need to keep resolutions below 2048 if you want hardware graphics acceleration to work however.

Waveshare supply a convenient HAT for the PI to drive their e-paper displays. The displays themselves are very delicate, in fact I managed to fatally crack my one trying to get it into the predecessor of this frame which is my first ever 100% designed by me 3D printed item:

This is the second edition, the one which doesn’t crack the panel . I chose black PETG for this to get a shiny piano black effect, unfortunately I didn’t use a high enough temperature as it’s been two years since I last printed in PETG and I’d forgotten. So it came out a bit rough … but it certainly does the job and I’ve uploaded the design to Thingiverse for others to reuse.

The crack in the panel produces display corruption which is very annoying as it’s €86 down the drain, however looking past that I found myself unimpressed with these displays as a dashboard. They don’t ‘pop’ enough due to needing ambient light. If they were trying to attract attention, I don’t think even if emblazoned in red with ‘DANGER’ all over anybody would notice them. The contrast ratio just isn’t there, and you’d need a spotlight shining on them to notice them which kinda defeats the purpose.

Most of my tests work out thanks to plenty of research beforehand. Some do not, and this was one of them. And that’s okay, better to have lost €86 than hundreds of euro had I chosen a bigger edition of this type of display. And I did score a bunch of Pi Zero 2 which albeit expensive, come in a useful PoE package and will be very useful down the line.

I may well be getting another order from Waveshare however. I don’t want to waste my lovely frame, so I might order a black and white e-paper display, something cheap while I also purchase something else I noticed there last time: a USB powered monitor.

Waveshare have a set of curated portable monitors tested to work with the Raspberry Pi’s USB supply. You just need to connect USB and HDMI and voilà, it works, nothing else needed. The portable monitor has a touchscreen, so you can even prod around. I went through all the portable monitors they have, and I believe this is their biggest which can be powered solely by USB:

https://www.waveshare.com/product/raspberry-pi/displays/lcd-oled/10.4hp-capqled.htm?sku=24647

This is a 10.4 inch IPS display 1600 x 720 resolution with 94% of sRGB for around €125 inc VAT. That is expensive, you could get a 15.6 inch touchscreen 1080p portable monitor off Amazon UK for €115 inc VAT. However that would need an additional power supply, and the display would be undoubtedly much less bright.

Anyway all those are decisions for later this week. It has just passed 3am, so definitely time for bed for me.

#house

Sunday 2 June 2024: 22:32. Here is the annual update to my periodic comparison of storage bytes per inflation adjusted dollar for magnetic hard drives, flash SSDs, and Intel Optane XPoint devices (you can find all the past posts here), which I have done every June since 2012:

Raw data: http://www.nedprod.com/studystuff/SSDsVsHardDrives.xlsx

This time last year I predicted:

This time last year I thought a recession would be upon us by now, as interest rates rose above inflation in order to bring it down. I still think that will happen, it just hasn’t happened yet – interest rates are indeed many times higher than last year, but inflation hasn’t really dropped by much. So either there will be recession sooner rather than later, or interest rates will have to rise some more. In any case, a recession.

It looks like the storage manufacturers were thinking similarly to me: there has been this year a hefty increase in the prices of hard drives and especially flash storage (and remember the above are inflation adjusted, so these are large price increases in real terms). I would assume this is because they curtailed production last year under the assumption that higher interest rates would reduce demand, and then demand didn’t reduce as much as expected so prices have gone up.

Unusually, this year saw a large increase in the price of both spinning rust and SSDs simultaneously. I think this is unprecedented. In previous years, either hard drives or SSDs individually saw large swings in price, but seeing both swing together in the same direction is new. By my reckoning, capacity per inflation adjusted dollar drops (i.e. large price rises) occurred in 2021 (hard drives), 2016 (flash), and 2011 (hard drives). For the hard drives, that was the covid pandemic/Thai floods and the financial crisis respectively; for the 2016 flash price rises, there was a sustained flash shortage for reasons google isn’t finding for me right now, but certainly to build a new fab takes a minimum of two years at best.

Optane’s 960Gb drive saw a hefty price decrease while the largest drive saw a hefty price increase. The 960Gb drive is now affordable – indeed, I bought one myself, and yeah it’s a latency monster. Sticking a few of those in RAID0 makes for some very fast storage, though it would need to drop in price a bit more still to justify say a 4x RAID0 array of them. CXL is supposed to be the long term replacement for Optane, and there are CXL memory expansion devices for sale right now, but they are very much enterprise priced and likely to remain a niche use case. I suppose that makes sense – my Threadripper Pro plus its very expensive motherboard can take a maximum of 1Tb of RAM (8x 128Gb), and its BIOS supports CXL memory expansion. 8x 128Gb Samsung ECC RAM currently costs around €4,600 inc VAT, so if you need more RAM than 1Tb you’re probably into a fairly rarified and enterprisey customer set. I currently have 128Gb fitted which actually comes from the Threadripper before the current board, and while occasionally it’s been constraining it hasn’t been frequent enough to make me consider an upgrade. I’m not that customer set, in other words.

Obviously Optane’s inventory and stock is being run down, so I’m hoping to pick up another three of those 960Gb drives at a very good price at some point. We’ll see how it goes. After that stock is exhausted, I suspend we will be waiting on SSD vendors to expose zoned storage to consumer level drives to see Optane-like i/o latencies – frustratingly, this is currently 100% a firmware choice by the vendors, they could flip it on tomorrow for recent SSDs if they wanted. Chances are it’ll only take one to do it to force everybody else to follow, so here’s hoping!

#ssdsvsharddrives

Saturday 1 June 2024: 20:07. We remain stuck in the timber frame supplier’s queue, so my house build has gone absolutely nowhere in the past three weeks. It has been doing wonders for my backlog of chores: I have rebuilt entirely the main house server which was long overdue; I have also rebuilt entirely my main dev workstation. I’ve also been a bit more attentive to my ISO standards and my open source than the negligence I’ve generally shown both recently.

I also finally got round to teaching myself how to use the design software for 3D printers which was another item long existing in my todo list. You may remember about eighteen months ago I picked up an Anycubic Kobra Go from the Aliexpress Singles Day sales which had impressive print quality for a printer under €200 delivered. I must be honest, since I printed a bunch of test prints and several ESP32 board brackets, I confess that I haven’t used it since, as I needed to go learn how the design software works.

It took a few nights of practice, but I’m now semi-useful with Autodesk MeshMixer, which was a free of cost 3D mesh editor. I say ‘was’ because when Autodesk realised 3D printing was no longer a hook for getting hobbyists into its wider software portfolio, they discontinued MeshMixer replacing it with a commercial alternative which many say isn’t as good. One can still find the installers for MeshMixer around, and yeah for a free of cost piece of software I would agree it is very good, a cut well above most free of cost software. It does have a fair learning curve, but I climbed it with a bit of effort.

Anyway seeing as there is zero forward progress on the house, the obvious thing to do is to print the house! My architect supplied me the current plans in STL format which is a straight export from his CAD program. I then used MeshMixer to edit down his original into something printable.

The Anycubic Kobra can do a maximum print of 200 x 200 x 240 mm, so I extracted just the site from the plans into a 200 mm width print which is approximately a 1:200 scale model of the whole site. I chopped the model vertically into three bits, so you can remove the roofs and first floor to see the rooms inside. I sliced it with Cura, and printed it using Hatchbox cool grey PLA which is a mid-range PLA filament costing about €25 with a good reputation online for being easy to print with, as printing a model this complex at the maximum size of the printer is a big ask for any hobbyist printer. I think you’ll agree it did a great job:

I had forgotten about the bed slinging affecting the Y-quality, so as is very obvious from the front of the house there was some wobble. The resolution is a bit coarse, for strength I required a minimum of three extrusions per thing, which means a granularity of 1.2 mm as the printer’s head is 0.4 mm. To get a four day print, I had the printer on maximum speed, which added to the roughness. I also made a bunch of mistakes in the mesh, the bottom right of the footpath and the bottom of the walled garden barely have a surface on them. I also had bed adhesion issues towards the top right of the print, I think the printer’s bed isn’t proper temperature up there as it’s a repeated issue.

The next logical step now beckoned: printing the main house at the full 200 mm size possible AND at the minimum possible 0.4 mm detail size. This is a very, very difficult print. Every timber stud will be printed. Every joist will be printed. The cavity between the outer block leaf and the timber frame will be printed. Even the ventilation pipes and where they exit and enter rooms will be printed.

I spent a few more days in MeshMixer and Cura for this one, throwing away my work twice and redoing it from scratch until the third one was looking pretty good. I didn’t make any of the mistakes with the previous model, and I reckoned an over extrusion of 0.6 mm for outer walls coupled with bicubic space fills with deliberate overknitting to anchor the layers together should do the job of creating a strong print. Everything within the outer boundaries does get a 0.4 mm resolution, only the outer boundaries had a 50% reduced resolution, with the idea being you would ‘smudge’ the plastic into its neighbours to help it adhere. What helped is that the design is specifically intended to be structurally sound with timber, steel and concrete – polylactic acid plastic isn’t those, but the structural qualities of the house design apply to it too.

This print took the full week, partially because I had it print the structural elements extra slow:

As I had rotated the print ninety degrees, the front didn’t get the effects of the bed slinging this time, but the sides did. The greenhouse was obviously too big an ask for this printer, which makes sense as its hot end is the second cheapest type possible, and it isn’t good at stopping and starting. Still, it made a reasonable attempt I think.

The resolution is now very good – you can clearly see the staggered studs in the walls around the bedrooms (the studs alternate sides). My bet on the overknitting of internal fill to hold thin walls together worked a treat. The cavity between the outer block leaf and timber frame is clearly evident. Even the ventilation holes into each room are clearly visible, and I can confirm during printing it did print all the joists between the floors, but you can’t see those now.

There are two mistakes in this build. The first is obvious on the roof where the layers did not adhere going into the gable. I reexamined my mesh after that, and found there was a gap (the roof tiles!) and the slicer emitted that dutifully. I hadn’t noticed because earlier slicer settings didn’t emit the gap, but after later tweaks it did and I didn’t notice. The second mistake is more subtle, but the floor of the house isn’t exactly flat, it has a slight tilt. I must have slightly messed up a rotation at some point as I didn’t realise until near the end that MeshMixer can do exact rotations, and I was rotating it by mouse movement and my hand must have wobbled. Oh well, there is very little in it.

I’ve sent this model for print by an online commercial printer for €150 delivered. It will be a Prusa XL doing the print, which has a maximum print volume of 320 x 320 mm so the model should be twice as big by volume. The printer he originally emailed me back to say this is an impossible print, it couldn’t be printed using any FDM printer. I sent him a picture of mine. Given the evidence, he said he’d have a try but no promises. His printer will take some weeks to do this print, even though the Prusa XL is much faster than mine, it is still a huge print taking a very long time. He suggested using ABA, it thinks it’ll be more tolerant to fine details and given the size of the model, PLA isn’t really strong enough to make a durable model. I look forward to it turning up in the post in the next month.

One big reason I chose PLA, and specifically grey PLA, for my print is because PLA is very paintable, unlike most of the other printable plastics. And grey is a good base for both dark and light paints. Megan intends to paint this model to test out colour choices for the house. And if she needs a second model for a second colour scheme test, it’s only a week of printing away.

As much as it was satisfying to make a sort of forward progress on the build by printing it, and it was a useful excuse to teach myself how to use the design software, I did find the printed model rather useful to aid conceptualising the design. I didn’t expect that: having designed this house exclusively by VR, we had walked all over it, flown around it, sat down on all the chairs, sofa and bed, practiced playing pool on the pool table, sat in the library reading books etc I really thought that there was no further understanding possible of this house design. However holding a 1:100 scale model in your hands … somehow it triggers something in you which VR doesn’t, and perhaps can’t. Something about the physicality, the realness of the actually existing thing … VR can approximate reality, but it can’t quite substitute fully for reality I think.

Anyway I suspect that will be as much forward progress as my house build will make in the next few weeks. Here’s hoping next time I write one of these posts something will have happened!

#house

Saturday 11 May 2024: 22:32. Very little has happened since my last post in my house build. We are basically stuck in the timber frame supplier’s queue, and there is nothing anybody can do but wait until they get to us.

It does feel weird to have free time back. I haven’t had any in so long, I am not used to not constantly having to find time to pare down chores lists. I am using the opportunity to clear backlog, all day today was chores and all day tomorrow will also be chores. Same as last weekend, and the weekend before that. But if this goes on much longer, I might actually have to do something non-chore which would be very novel given the past two years.

I did refine the outhouse buildup I described last post to remove the heavy concrete roof, which in turn reduces loading on the foundations which in turn means I can economise on strength of materials used, reducing costs. I think this will be pretty close to my final design:

The structural calculations look fine with very healthy safety margins. The flat roof with the 622 centres will have quite a bit of flex when you walk on it, but I expect to almost never walk on it, so I don’t care and having 622 centres means I can avoid cutting the blocks of EPS which come 600 mm wide. The lintels should be all very straightforward, the widest span should be 2.4 metres, online tables think a 3200 x 215 x 100 lintel should be fine which is a one block overlap each side. As it is such a simple building, there isn’t really much more to it.

Obviously as the house design is finalised, and nothing more can happen until the timber frame design begins, there isn’t really much else to report. The previous mortgage offer from the AIB expired as there was no way to draw it down, so we now have to apply for a new mortgage again from scratch. Yay. The rebooted Passive House certification after our previous certifier couldn’t proceed is proceeding very slowly, my architect clearly has other work on and forward progressing the PH certification is not a high priority. After all, we already did this bit with the previous certifier, so we are simply re-treading the same process without much expected gain from it. Going through the motions as it were. We will only return to new ground later on in the process.

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Right now, if there weren’t a thick blanket of cloud above me, there would be aurora borealis which are exceedingly rare this far south. I caught a brief seven minute long or so view of them last night before heavy cloud rolled over them. I had never seen them before in my life, and they were very cool.

I saw greens, reds, pinks and purples all with the naked eye stretching over most of the sky. They were quite noticeably twisting and pulsing in the sky even within my seven minute window. I could see the cloud rolling in, so I just stayed there and drank it in knowing my time would be short. It is quite possible I will never see them again in my lifetime.

I didn’t have my phone with me as I didn’t expect to see them, and I didn’t want to miss any of them by returning inside and ruining my night vision. So I did not take any pictures. Megan missed them entirely last night, and took a ninety minute drive after dark around the country back roads to try and luck out on a gap in the clouds. She returned deflated, having failed to secure anything more than a very fleeting glimpse.

All this was where my rented house is, which gets a fair bit of light pollution from all the urban build up. Out where my site is is much nearer the Irish dark sky reserve and has as close to dark skies as remains possible in Europe. Unsurprisingly you get even better views there than here. My neighbour at the site Rob managed to snap these:

That first picture that’s my site on the right, and the second is a 180 degree turn from the first. The pictures are much more colourful than with the naked eye of course, modern phone camera sensors are better than human eyes. But multiple colours were very much visible without electronic aid, which I read online is unusual enough even very far north. This coronal mass ejection being strong enough to reach so far south might only happen every twenty years or so, and not usually in a way the whole northern hemisphere can see it two nights in a row.

Real shame about the cloud cover though.

Anyway here’s hoping this time next month we might be making forward progress on building this damn house instead of me having to actually go do a non-chore activity!

#house

Saturday 6 April 2024: 22:35. As described last post in my house build, if we didn’t commence the build before the 24th April we would lose €14k of subsidy from the government. I am glad to report that we have successfully commenced the build:

We ended up not fitting neither the land drain nor the soakaway as the soil 1.5 metres down turned out to be much more dry than expected, and thus capable of handling an inundation more than needing additional drainage:

(the pool of water at the bottom shown is due to rain at the time, at the point of excavation the subsoil was surprisingly dry)

As the land drain would get crushed by heavy machinery if installed now, and seeing as it wasn’t necessary given how dry the subsoil is, we left it off until the outer block leaf gets erected, which is when the services will be installed.

First thing which went in is the subsoil heat exchanger, which is 150m of HDPE water pipe buried at 1.5 metres down. Here is its trench mid-completion:

On top of that came a very great deal of T2 stone, which one of the truck drivers cheerfully informed me is one of the most expensive loads they do at €505 ex VAT per twenty tonne load. Yay. The stone came from the quarry at Ballyhest West, approx 13.2 km away from site. This is a quarry whose limestone originated in shallow waters and therefore has a distinctive blue tint, unlike the white limestone of deeper waters.

Last post I estimated that 150 m³ of T2 rock would be needed. I can tell you now that nineteen twenty metric tonne loads were delivered, which is 380 tonnes which is approx 190 m³. The reason we went a quarter over estimated is because some of the excavations exposed soft soil which had to be dug out deeper to reach subsoil. In particular, just under the master bedroom at the front right there was a €505 ex VAT costing hole, as that is what one truck load of T2 stone cost me:

As much as I was rather wincing watching a full truck load fill what will be supporting my future bedroom and nothing more, it could have been far worse. One of my fellow neighbour self builders Patrick happened to pop by, and he was telling me how he had to drive forty-three piles to support the foundations of his future house. Due to driving piles, no insurer will cover his self build, and so he is exposed to unlimited liabilities if anything goes wrong. I spent two weeks trying to find somebody who would insure my self build. It turns out there are exactly three insurers on the current Irish market willing to underwrite a self build timber frame (there would be far more if it were a concrete block build aka ‘standard build’ (which is defined to exclusively be concrete block in Ireland), or if a main contractor were doing most of the work). Anyway I went with https://selfbuildprotect.ie which is a trading name for MDRB insurance, one of the larger brokers in Ireland for a cool €2,200 for eighteen months. If that seems a lot, it is, however it is proportional to the cost of rebuild which for me is rather a lot.

T2 stone is very much ‘expensive gravel’, it has the consistency of gravel, it looks like gravel, it feels like gravel, and it compacts like gravel i.e. it is barely worth running a whacker over it, though we did so anyway. Unfortunately it must be guaranteed cleaner than gravel, and you can see here the juxtaposition of the T2 stone with the cheap-as-possible gravel previously at the front of my site:

Both came from Ducon Concrete, whose head office is just up the road from me. But T2 stone comes with guarantees, whereas the cheapest possible chipped limestone from them does not. Hence the price (and colour) difference.

We did not in the end lay entirely T2 stone everywhere precisely because it really is like gravel i.e. unstable. We put four inch down towards the front where the future driveway will be, and then more four inch down to the right where the future patio will be, and between now and the future patio it will be where the heavy trucks will drive in. On top of the four inch down we put a layer of two inch down. Both four inch down and two inch down are quite a bit cheaper than T2 stone, so doing this saved me a few hundred euro. However unlike T2, both four inch and two inch down compact themselves into a rock solid surface almost like a road – indeed, this is what a Roman road was, compacted crushed rock of layers ever decreasing in granularity, and their roads lasted centuries before becoming unusable due to wear and tear.

Finally, a full twenty-three loads of soil were removed, at approx 20 tonnes per truck, which is four hundred and sixty tonnes of soil. So 380 tonnes of expensive stone in, 460 tonnes of soil out. Each truck of soil removal cost me €270 ex VAT, because I live in the EU and anything which could potentially involve waste removal is hideously expensive (in most parts of the world topsoil removal means them paying you for the topsoil, but not in the EU where removing a valuable commodity costs you money). In case you’re wondering why?, the answer is apparently any unregulated transfer of soil from anywhere to anywhere else comes with a €50,000 fine. So basically due to regulatory capture, the price of disposing of anything at all gets tainted by the 1% of disposals which are very expensive to dispose of, and for obvious reasons if you’re disposing of toxic waste you’re getting an absolutely wonderful deal at €270 ex VAT per tonne with the costs spread onto everybody else. Yay.

What may not be obvious from the photos is we kept the very best of the topsoil which is a dark brown material, very very good topsoil. That is currently a three metre high mound in our future walled garden.

As much as installing the pre-foundations cost me at least €20k (I haven’t actually gotten the bill yet, but at least that much materials went in or were removed), it does leave a rather pleasant ‘sea of stone’ which even walking around is somewhat satisfying. Here it is being flown around by the drone:

In case you were wondering, the stoned levelled area is approx 630 m². The total site is 1400 m². So, approximately 45% of the total site will be put under stone initially, with pockets later carved out as grass. I very much agree that it doesn’t look like half the site by area has been stoned – it looks like much more – but that there is what the maths says.

Outhouse

The groundworks guys double-triple-quadruple recommended to me in the strongest possible terms to not lay the sewers for the house until no more heavy machinery would be traversing the site. That effectively means that us moving into our house is blocked by the completion of the outhouse, so it has just leapt up the priority queue.

To be honest, I really hadn’t given it much thought until now outside its basic design which was needed for planning permission, which is this:

Neither me, my architect, nor anybody else has touched that design in well over a year. It’s been that low priority.

I had had some ideas of maybe building it with ICF i.e. polystyrene hollow blocks you pour concrete down the insides of. But the house quotes I got for ICF were ridiculous, and for a crew to come out to do a small box 10.36 x 5.1 metres there would surely be a substantial premium for them turning up at all.

I could do timber frame again for the outhouse … but that kinda feels lazy. Plus, I really don’t need passive spec for the outhouse, and as it’ll mainly be a gym, concrete block inside walls would be very attractive for hanging mirrors, bars and other heavy things. Plus, painted concrete blocks is very much how gyms are, so it would give the desired ‘feel’.

That got me onto wondering how you’d do this if it were a conventional new build in Ireland, how much that would cost and so on. Generally new builds in Ireland are still strip foundations where you dig out where the walls will be to about 1.2 metres down, fill the bottom of that trench will liquid concrete to provide a footing, then raise the walls using block on flat from there (often called the deadwork, as it’s all underground). As you near the floor level, you switch to expensive aerated concrete blocks to provide a thermal break, usually three layers, with 200 mm of expanded polystyrene (EPS) insulation under the room floors and a 50 mm screed to yield a floor with an average 0.18 u-value, which is the legal maximum in Ireland since 2019.

Note my qualifier ‘average’. Those aerated concrete blocks they have seven times lower thermal conductivity than standard concrete blocks, but EPS has a thermal conductivity 42.9 times better. If you are perforating your floor insulation at regular intervals with a thermal bridge seven times more thermally conductive, you get much worse quality floor insulation. Yes, the average might be good, but it won’t be even, there will be ‘cold spots’ and if they are cold enough relative to moist air, they’ll condense i.e. you get mould. Most new Irish builds even post 2019 regs still develop mould after a few years – much better than pre-2019 no doubt where some of those new builds became riddled with mould within a year. But still, not great.

It would annoy me if my gym got mould into it, so I’m rather liking the idea of wrapping the foundations in continuous EPS so there are zero thermal breaks. In fact, let’s just wrap the whole building in unbroken EPS:

All the above is 100% my design and calculations, and I am neither an architect nor the right kind of engineer. Still, designing the main house has gotten me much more familiar with structural and thermal design than I was. A simple box of a building is now well within my capabilities, and I kinda enjoyed testing my new skillset above.

You might wonder why use the expensive aerated blocks within when they are completely thermally broken from the outside? It’s a good point, and that may get jettisoned yet for cost reasons as they are more expensive per sqm than anything else. Standard concrete blocks cost about €30 inc VAT per sqm, so less than half the cost. I had been thinking weight reduction, but also that you wouldn’t get problems such as condensation on these from sudden temperature changes which will be likely, as the gym won’t be in continuous use and will instead usually go from cold to warm very quickly for short periods of use.

The other thing I’d like to get rid of is the concrete slab for the roof if possible. It creates a cold roof and all the insulation being on the inside will risk interstitial condensation. It would be better if the insulation went right up to the flat roof membrane, thus making a warm roof. However to achieve that, I can’t see any way of avoiding the roof joists themselves becoming thermal bridges as they’d need to poke out far enough to provide shelter for the wall insulation. At 0.13 W/mK timber is better than those aerated concrete blocks, but still many many times worse than EPS. I would also need a continuous slab of EPS200 between the joists and the roof membrane, which is €1,600 inc VAT of EPS just for that alone.

Or would I? What actual weight lies on that roof? EPS70 can take seven metric tonnes per sqm with a deformation of under ten percent, and there is absolutely zero chance of that kind of weight.

The KORE EPS70 comes in 600 x 1200 slabs, so I’m wondering if I made the roof joists at 600 centres, a 220 x 44 joist should span 4.385 metres and the gap between the inside walls is 4.27 metres. The other package for KORE EPS70 comes in 1200 x 1800 slabs (exact same price per sqm), so if a warm roof won’t take much load, why not sandwich a 80 mm EPS70 board between two 18mm OSB sheets, and that’s your warm flat roof?

I reckon such a build up would have a roof u-value of 0.12 W/m²K; if the EPS70 between the OSB boards were 50 mm instead, then 0.135 W/m²K. That does feel more cost effective, and maybe I’ll do up the detail for that with costings at a later point.

Anyway, for the detail above:

• There is 52.84 m² of roof and floor, let’s call that 53.
• There is 89.67 m² of wall minus approx 13 m² of glazing = 77 m².
• 13 m³ of T2/T3 stone needed which would be 26 tonnes or so, so €600 inc VAT.
• Twenty-two lengths of 220 x 44 x 6m wood needed at €35 inc VAT each is €770 inc VAT total.
• Approx €3,150 inc VAT for the roof insulation.
• Approx €2,100 inc VAT for the floor insulation.
• Approx €2,300 inc VAT for the wall insulation.
• Approx €4,804 inc VAT for the insulated block wall.
• Approx €6k inc VAT for the charred larch outer cladding.
• Approx €8k inc VAT for the glazing.
• Approx €28k inc VAT in total excluding labour.

Obviously I omitted the hollowcore slab as I’m hoping to engineer it out of being needed, but it seems reasonable to me I can get that outhouse done for about €50k inc VAT or thereabouts. I originally had €80k inc VAT as a guessestimate, so that’s rather better than expected back when I first started planning this a very long time ago.

Anyway bed time for me! I should send some emails enquiring about progress before I go to bed …

#house

Saturday 16 March 2024: 20:14. A key deadline is getting close for my house build: on the 24th of April the council development contribution levy subsidy will expire, along with the Irish water connection fee subsidy. These are worth about €8k and €6k respectively, so it is important to claim them. Had the previous builder not fallen through, we would have commenced the build before the deadline, now with the change in builder we had to come up something which is sufficient to claim that the build has commenced. To that end, marvel at the first round of groundworks which shall be commenced in a few weeks from now:

As the structural engineering isn’t done yet, we don’t know the locations of any of the service popups for sure, so we can’t do those. As this will be a raft not strip foundation, there isn’t any deadwork, the house ‘floats’ on a ‘sea’ of chunky crushed rock about a quarter metre deep. In some ways this makes installing the pre-foundations easy – instead of having to pour concrete footings and lay concrete blocks to support the future walls, you just lay (in this case) a 28.5 metre x 20.7 metre x 0.25 metre layer of T2 stone which is crushed rock between 4 and 40 mm in size. On top of that LL Structures our timber frame suppliers will compact and level T3 blinding, which is crushed rock between 0 and 4 mm in size, but that will be after the groundworks guys come back to dig up what they’re about to lay down to install all the service popups, which is some months away yet after their locations have been written into stone (heh!), and a surveyor has come out to mark out the exact locations of every pop up to within one centimetre. According to the groundworks guys, laying it down and then digging it up again is how you achieve exact service popups in any case, it is why raft foundations are ‘not good value for money’ compared against strip foundations, so the work would have to be done exactly as we are doing in anyway. We just have bumped this first stage up to before April 24th to claim the subsidy, that’s all.

As you can see in the diagram above, around the outside of the house there needs to be a land drain about 0.25 m from the outer walls. We need to install this now otherwise rain would fill this hole we are digging with a standing pool of water, which is not good for retaining a solid footing. It will be temporarily connected to a soakaway at the back and to mains stormwater at the front, and that should hopefully keep these sub-foundations from getting waterlogged.

I reckon about 150 m³ of T2 rock will be needed. Assuming 0.75 m³ per tonne, that would be 200 tonnes @ maybe €60 inc VAT per tonne so that’s €12k just for the rock alone. Plus €3-4k for pipes, inspection chambers etc, so €15-16k just for raw materials. Sigh. So much money.

But then, it is rather a lot of space, we shall be filling maybe half the total area of the site. To put it into context:

There is obviously a lot of rock going in around the house. This is dual-use – initially it will support the crane dropping in the timber frame panels and the other heavy machinery, however after that it will be the foundations for the footpath surrounding the house, the patio to the west (right of house in this picture), and the driveway to the north (bottom of house in this picture). So all of it will be needed, and none of it will be wasted. If you build a big house, it costs a lot of money!

The aerial photography

Those who read regularly may be thinking ‘aren’t those fine looking shots from above?’ especially when the satellite images I purchased from startup SkyFi weren’t great. You would be correct – they were taken by a new acquisition of mine, a second hand DJI Mini 3 Pro.

Even purchased second hand, this is not a cheap drone, they cost well over a grand new if purchased with the controller with a screen which saves faffing around with a mobile phone. The money does buy you rather good images though, the picture above is considerably downsampled from its original 48 MP image in which I can clearly see individual leaves on plants. DJI, being the world leader in drones and having overwhelming dominance in the drone market worldwide do come with a price premium, but in return you get a polished experience. Flying the thing is very fluid, very easy and natural. It copes surprisingly well in gusty windy weather, doing a very good job of holding position in all three axes. It has a bunch of safety gear on it to prevent you running into things when flying. It weighs under 250g, which means you are allowed to fly it over people once you have gained your drone pilot’s licence, which I have.

There are some negatives though. The first is the very annoying and completely artificially imposed limitations in features in software – for example, the Mini 3 Pro has the hardware to execute a preprogrammed flight path in 3D space like the Mini 4 Pro, but DJI have locked it out as product segmentation. They do allow a particularly braindead implementation (more on that later) because the hardware is capable, and they may enable the full fat unrestricted implementation in a future firmware update (it wouldn’t be the first time, they have a history of enabling ‘new model’ features on older models after a while), but for now it’s irritating to be locked out by software like this. The second negative is the DJI Fly App, it is huge and very heavy on resources. This is acceptable on a high end smartphone, but they did not fit their screened controller with a high end CPU, so the DJI Fly app on their own DJI RC 2 controller is slow, laggy, and annoying to use. Finally, the third negative is getting everything to register with everything else was far, far harder than it should have been. I ended up having to hard factory reset every bit of DJI hardware from a PC using a USB cable and DJI’s PC diagnostic utility before they’d talk to each other. Maybe that’s the price of used kit, I don’t know, but it made for a very frustrating (and slightly nervewracking) first few days after receiving the delivery. I will say in fairness the internet is chock-a-block full of helpful advice with DJI kit, and I fixed each problem as it arose quickly enough. It just took more time and hassle than it should have in my opinion.

Anyway, onto the preprogrammed flight path facility. This works by you telling the drone to fly between various points in 3D space with various camera angles, recording video as it goes. If you execute this daily, you could build a timelapse video of the house being constructed as you pan around the building because the video would overlay exactly onto the others over time.

As mentioned above, the Mini 3 Pro does have this feature, but it is restricted to an implementation which takes a photo every three seconds as the drone moves very very slowly between the programmed waypoints. It then stiches together the photos to make a video. Here is my last attempt at this, but transcoded down to 720p from the 4K original:

I’ll firstly apologise for the random slowing down and speeding up, that above is my best attempt so far, eyeballing out how to equispace programmed waypoints is harder than it looks.

There are plenty of other issues not my fault though. Firstly, if the sun comes in and goes away during the approx fifteen minute shooting time to generate twenty seconds of video, you get a most unpleasant lighting change between frames as that video demonstrates in full. Secondly, there is no motion compensation applied as there is when recording video normally, so any gusts in wind are very noticeable in the video as things move around more than they should. Thirdly, it just takes so damn long to do the recording, generally consuming most of a battery, for what ends up being a very short video for all that time and effort. Again, what really irks me here is that the hardware is more than capable of that drone whizzing around those waypoints video recording in 4K and 60 FPS with motion compensation running – which would produce vastly vastly better results, and be done in a minute or two rather than me waiting around fifteen to twenty minutes bored.

There is another annoyance – if you really are going to force it taking photos every three seconds, why are they capped to 4K and not giving me the full 48 MP it’s capable of? Then at least I’d get 8K video for all the time it takes. DJI, not that you’ll read this nor care anyway, your artificial software lockouts just suck.

First person view

In addition to the drone, I also purchased the DJI Goggles and DJI Motion 2 joystick controller. Yup, you can become the drone, and fly around rather like a bird or an airplane. I also purchased the wide angle lens which makes more sense for the FPV view, but I forgot to fit it before recording this which as a 4K 60 FPS video is far too big for my website, so here it is on youtube:

This was my very first time operating the thing in FPV, so you probably noticed I got much less jerky in the controls towards the end whereas at the beginning I was like ‘ahhh tree!’ and I yanked it away. I had the safeties on, which limits maximum speed so the collision detection has time to react. Those can be turned off, and the drone will go about twice as fast again.

What isn’t obvious from the video is the effect the googles have on your constitution. I’m fairly tolerant to VR goggles compared to most, I can wear them for an hour or so before they get to me. Well, at least for the Oculus or Google’s now abandoned phone based VR. I can’t say the same for these, even soaring high up over the estate as a bird had me wedging myself against the shipping container as I was finding it hard to keep standing. When I began swooping over the site, I began to feel very unwell indeed. Luckily, I had little in my stomach that morning, and I made myself keep going until the batteries on the drone ran out which was a few minutes after that video ended. After which I felt quite, quite nauseous for several hours, and even watching it again there now it’s bringing back the yacks a bit.

The headset drone experience – at least for me personally – is definitely best had far up in the sky ideally sitting down on a chair. The goggles do head tracking, so you can look around in 3D as if you were in VR, and in fairness to DJI it’s pretty seamless, though I suspect the likely hundreds of milliseconds of latency needed to actually physically turn the drone to match your head is what induces the disorientation. I could definitely see me using them to experience spectacular nature as if a bird, and I can see them being useful when checking the build of the house, so I’ll be keeping them, at least for now.

Indeed, I didn’t spend all this money on drones and accessories just for aerial photos and pretty timelapses. It will be used during the build to inspect the work being done in order to save me having to climb up onto the scaffolding or put up ladders. I don’t care for heights, plus it’s time consuming to set up and tear down height scaling equipment. It is much quicker just to fly the drone nearby and use its excellent camera to zoom in, and that’s the principle reason I bought it.

All the testing so far indicates my research was accurate, and it is more than fit for this purpose, especially as it will also fly indoors which lets me checking the roof of the vaulted ceilings without having to bother with the scaffolding tower. I think it’ll get good use and save me a lot of time and hassle.

#house

Thursday 22 February 2024: 11:14. This time last month in my future house build things looked like they were finally moving forwards. The plans were finally finalised, they’d gone off to the builder at long last, and it was now a matter of weeks before we would commence the build. The mortgage would get drawn down before it expires in May. All was looking rosy.

Unfortunately we had to go get a new builder, so we have been pushed back by six months to the end of his queue and the cost of the build has jumped by over €100k. Which really sucks.

What went wrong?

The builder we had up until now had started making cold feet noises around October of last year. Up until then he was taking us to Builder’s Finish, now he was refusing to give quotes for Builder’s Finish and would only talk about Timber Frame Supply and Install, which isn’t what I had wanted as I had been specifically seeking project management. That got worse as we approached Christmas, and despite me having paid him a retainer, getting information about what he was willing to build and for what price became ever harder. As we are not building a standard Irish house, but rather the first certified Passive House Plus (note the Plus, it is one grade stricter than normal Passive House), we can’t and never were going to be able to use standard Irish build techniques. Indeed, we can’t even use standard Passive House techniques. The builder who has many years of experience building Passive House, knew we were targeting certified Plus from the outset. But I don’t think he was prepared for just how custom that was going to make the build, and time needed to define cost effective build approaches in the very shallow Irish building supplies market where there isn’t much choice, and prices for some materials are unusually high compared to elsewhere in Europe. As we didn’t know and couldn’t know if some material combination was cost effective or whether the builder was willing to do it at all, that necessarily involved a lot of back and forth, and the builder he was not supportive of this dialogue.

Furthermore, as recounted last entry, over Christmas we had to move from rigid phenolic foam insulation to 300 mm cellulose which needed a twin stud, as the unusually humid Banteer climate is too much for rigid foam insulation. That obviously needs more work to make the frames, and more insulation to fill them. So just as we were about to pay the first big deposit, in came a revised quote €110k higher. This came as bit of a shock at the time. It was 31% higher than the preceding quote.

Now, to be fair, I think that quote was fair for the spec involved. I didn’t think so at the time obviously, so I went and re-sought quotes for the post-Christmas build spec, some came in under, some over, but the ballpark was similar. To put it bluntly, if you move from a 0.16 u-value to a 0.11 u-value, that is a 31% improvement in insulation. The considerably thicker walls now need more timber, more support, more effort to manufacture to nail all those bits of timber together. It is as simple as that: one third more house costs one third more.

Choosing a new builder

While our former builder had given a fair quote I think, unfortunately once you enter that price per sqm now being charged, the landscape changes somewhat. At sub-€1,000 per sqm for sub and super structure supply and install, you get an economy-orientated custom design house build, so while the design is unique (and therefore a step above a catalogue once off build), there will be a single cost-optimised system and you can’t deviate from it (as has since become very obvious). In addition to a fixed choice build system, there will be various small compromises in terms of customer experience and build quality, but overall you get good bang for your buck, if you’re happy with what that system delivers.

However once you’re into the ~€1,250 per sqm shell price range, you’re getting into wealthy person builder territory – as in, the kind of builder who caters only to the very wealthy, where custom build-ups, custom materials, and custom ways of assembling them become more normal. This is because you’re now into performance-orientated or quality-orientated building, rather than optimising mostly for cost.

As an example, take Advanced Housing Systems who are a British based builder we got a quote from. They take you to nearly the end of First Fix, with only electricals, plumbing, and ventilation missing – but all the internal plasterboard and insulation is done (you might wonder how this works, they build conduit and ducting into their premanufactured panels for all the wiring, plumbing etc). They only use wood cut from their own forest in Devon, and only sheep’s wool from their own flock of sheep as insulation. Everything is done in-house, no subcontractors, so everything gets the personal touch. They’ll deliver and install your house anywhere in greater Europe, from an empty site they are done within one month.

This probably sounds expensive, but they come in at €2,083 inc VAT per sqm. That price includes M&E design, structural design, all the engineering, getting the stuff over to Ireland and hotels for the workers to erect it. Once everything is factored in, they’re actually very price competitive overall to an Irish builder, all the u-values are 0.10 compared to the 0.15’s you see from ‘passive standard’ builders, theirs is undoubtedly a superior quality build for the discerning client. And you’re probably thinking there must be a catch here?

Indeed there is: it’s financing. There are three mortgage lenders in Ireland who do self builds. Their stage payments are hardcoded to six stages based on the assumption everybody builds a concrete block house, and they pay in arrears. They do not allow for the large advance payments necessary to fund the offsite construction of timber frames. They do not allow borrowing in addition to the mortgage. You therefore need to front huge amounts of unborrowed cash in advance, and for that, you need to have in your bank large amounts of cash. Which I do not, as I’ve spent it as you’ve seen in the quarterly House build spend updates.

AHS because they supply more than most in their package they have larger upfront cash flow needs than most, so how Irish bank mortgages work is particularly ill suited for them especially, and that was the sole reason I had to rule them out (I would have loved to have chosen them otherwise). And, in fact, this same problem of financing also affected the former builder, because he supplied all the plasterboard and internal insulation (unfitted) you’ll need, and thus like with AHS his higher cost quote created a substantial cash flow problem for me. When he increased his quote by that much, it’s not that I couldn’t afford it overall, it’s that I can’t raise the cash flow to make the stage payments paid in arrears work anymore. You may remember that my mortgage is capped to 90% of valuation, so I can’t borrow more, I can’t borrow elsewhere, and I just don’t have the cash needed nor can I get it. It’s as simple as that.

So, when choosing a new builder, I had to choose ‘less is more’: the less they supplied in their package in one go, the less cash upfront I needed before the bank mortgage pays out in arrears. Paradoxically, this almostly certainly increases the overall cost as much more now needs to be done by direct labour, also it also hugely increases the amount of project management I need to do as much more needs to be done now once the builder has departed. Most unfortunate, but that’s the main reason why poor people remain poor: they don’t have the cash flow to avoid being forced into expensive poorly timed purchases. Same principle applies here: my lack of cash flow will increase my costs overall.

The builder chosen: Long Life Structures from Galway

We ended up plumping for Long Life Structures from Galway who have quoted the supply and install of foundations and timber frame for €1,234 inc VAT per sqm to airtightness. Internal partitions will be studded out, but all internal insulation and plasterboard will be supplied by me. It also doesn’t include the considerable fees I have spent and have yet to spend on M&E design and structural engineering, which the AHS quote included. As I mentioned earlier, I think the AHS quote cheaper overall, and certainly for the u-values for the euro they are far better bang for the buck, but in cash flow terms I can’t afford AHS.

LL Structures aren’t too bad for the u-values though in their standard buildup (which is a cost optimised derivative of those from Ecological Building Systems):

• Floor: 0.10
• Wall: 0.134
• Roof (sloped): 0.15
• Roof (flat): 0.09

These u-values are from my own calculations incidentally. You may not be surprised to learn that some u-value claims by some builders don’t add up. LL Structures actually claim worse u-values than the Passive House u-value calculation method, so I think those numbers above are almost certainly an upper bound, and we’ll get quite a bit better than those in practice. More like walls and sloped roof at 0.11.

What isn’t described by u-values alone is thermal bridging, which is something a lot of ‘passive standard’ builders particularly skimp on when thermally breaking the timber studs from bridging between inside and outside (u-values are the average, thermal bridges are the quality). You may see no thermal break at all, or a 25 mm or 50 mm break, and usually to the inside of the AVCL as that is cheaper though inferior, as it moves the interstitial condensation boundary inwards, which means you get things like condensation around the edges of your window frames, which can become mould growth. LL Structures apply 80 mm of thermal break to the wall studs, and it is on the outside not inside which is the more expensive but superior option. Similarly, for their flat roof they thermally break the rafters on the outside with 130 mm of unbroken cellulose. Where they do fall a bit short (as you can probably guess from the u-values above) is on the sloped roof, there the rafters are only mildly thermally broken, using a 220 mm + 75 mm nailed together stud, which is still better than an unbroken stud. The 295 mm space is fully filled with cellulose. We do have roof windows, however if you use the more expensive insulated flashings then moving the interstitial condensation boundary inwards by adding more insulation internally won’t produce the same mould problems as you’d get for wall windows, so that should work okay.

As would be usual for builders in their per sqm price range, they use only 100% natural materials and nothing synthetic, so no PIR board for insulation, no plastics, nothing with volatile organic compounds except where required by law (timber preservative impregnation). Like with AHS, they don’t use subcontractors, everything is done in house by their own employees to ensure the personal touch. Obviously I did ask around about them before hiring them, multiple independent sources said they were good. I pulled all their recent company accounts from the public record, they had a bad few years from covid lockdowns and the build material costs going up so suddenly, but they’re back into profit as of last year. I went to see one of their sites mid-build, construction quality and detail was better than average. I saw multiple small touches here and there, stuff most builders don’t bother doing. Nice.

Here’s hoping it’s all smooth sailing from now on!

New Passive House certifier

Passive House certification comes in two stages: (i) design preassurance and (ii) the actual certification. Bob Ryan our certifier, has decided to retire from certifying so he had only done (i). That means I will need to hire somebody to replace him for (ii), which is inconvenient.

I have received a quote from a potential replacement, and hopefully that will be the end of yet another thing going wrong.

New mortgage

As there is now no way of drawing down the mortgage before May, we will need it extended. However the cost has also gone up, so of course they want me to reapply in full from scratch . Which is something like the third time I’ve had to supply them with all my financial statements blah blah blah.

I’ve been effectively applying for the mortgage now for two years. I’m going to have to go rejump all those hoops once again like a good little show pony. It’s getting really very tiresome. This is the kind of hassle and inconvenience which results when you change builder last minute – if you can, try to avoid doing so yourself!

Still no entrance door

Last post I had a picture and a cool video for a Sika entrance door. I was hopeful of acquiring one at the time, since I am not.

Sometimes it really sucks to be on an island far off the coast of Europe, and nowhere near a big enough city. Finding decent entrance doors for a good price really shows this. That Sika entrance door (manufactured in Northern Ireland) had a quote for a cool €4,990 inc VAT for supply and install. I know for a fact you can pick up the door in Dublin for under €2k inc VAT, but then you’d need to transport it and install it.

€5k is at least better than the €9k Internorm wanted to supply and install their entrance door. But both quotes are quite frankly ridiculous. It’s a single fucking door, it’s not worth the cost of replacing my or Megan’s car, which is what a spare €5k would do for us. I did hunt around for other reasonably priced doors and we’ve shrunk the door opening to a standard 1000 x 2100 to aid that, however I’m currently thinking I’m just going to ask Nordan for the entrance door too, despite that their entrance doors kinda suck. It’s just easier and there are bigger fish to fry.

New pictures of insides

Last post I mentioned that there had been a few design changes after the PH design assurance stage, mainly that the walls have become thicker and the steel structural support has been moved inside the airtightness layer. Two years ago I rendered images using the then state of the art Unreal Engine 5 which involved a lot of work to convert the BIMX to TwinMotion, and from there to UE5. Back then, the 3D render from Graphisoft for their BIMX was best described as ‘basic’, but they’ve made very significant strides forward even in the past six months such that these look okay, and my urge to render them via UE5 isn’t as strong.

Those definitely aren’t terrible, there is now a reasonable attempt at accurate shadows and lighting, and the high resolution skydome does no harm either. Without doubt nowhere near as good as Unreal Engine 4 never mind 5 – the lack of light bounce and reflection is especially noticeable – but these are sufficiently good that I’m not leaping up and down to go through the hassle of a TwinMotion to UE conversion cycle. These will do.

There is now a pronounced steel beam, coloured here blue (we will be using ochre red in reality). We deliberately have it exposed where possible now, so you can see it holding up the house over the mezzanine, and within the home office.

That last picture shows how the curtain glazing at the front has quite noticeably shrunk due to the walls going from 0.4m wide to 0.5m wide. Because both outer walls took 0.2m, but also the two columns in between, those windows went from over a metre wide to under a metre wide. They’re still the central feature of the house design, just not as pronounced as before. Obviously shrinking them did also have an outsize impact on heat loss to the north, so it greatly improved our PHPP numbers, and it’ll also reduce our glazing bill. Still, feels a bit of a shame, equally also very glad to be spending less on glazing now we’ll be spending more on structure.

Finally, there is an alternative render of the house which is kinda cool:

This is the house ‘nude’, as it were, so you can see all its drain pipes, ducts, joists and of course steel frames. Plus all of the gubbins which lives underground like sewerage and storm drains.

What’s next?

Now the €25k deposit is paid to LL Structures, the General Arrangement drawings will begin in about five weeks from from now, so last week of March. That might take a month, so to end of April. Then begins structural engineering design, which might take us to end of June. At this point off-site construction of the timber frames can begin, and the foundations and steel frame can be installed probably during July. The timber frame should therefore get erected in August.

Before then, we need to ‘commence’ before April in order to claim a development contribution levy subsidy. We think installing services popups and the base for the raft foundations is doable before then, so that’s the current next highest priority as it’s a saving of €13-15k or so.

Before we can do that, myself and Megan need to sign off on the final final final plans which once sent to the timber frame manufacturer shall be immutable forever! We’ll do that this weekend, unblocking everything else next week.

#house

Sunday 21 January 2024: 01:09. There has been a major step forward since my last post in my future house build: the plans were finally finalised, and sent off to the builder. The builder has come back with his first round of questions, and we should ship a set of answers to him early next week. I would expect a few more rounds of that with the builder before he signs off, then begins the structural engineering design.

Design changes post Passive House design assurance review

Visible changes since the last time I posted computer renders here are few, but quite a lot non-visible did change:

1. We moved from a 140 mm tinber stud wall filled with phenolic foam to a 300 mm split stud filled with cellulose. This caused the side walls to go from ~0.4m to ~0.5m, which is a lot fatter. The cause was during PH design assurance Robert Ryan our PH certifier found runaway moisture build up in the walls in the humid Cork climate which is our site location. To be clear, it was very close, it took six years in the model for the walls to become saturated due to accumulating more moisture annually than being able to expel it. In the real world, that assembly could have been absolutely fine for twenty years, or riddled with mould and needing demolishing within two. It would depend on the actual weather, obviously. And no shortage of timber frame houses are built in Ireland and are just as close to the margin, and are fine (or not!).

   Obviously, had our climate been just a touch dryer e.g. in Dublin, there would have been zero issue. But it just goes to show how careful you need to be with foam insulated timber frames in a humid climate.

   Anyway the cellulose airs out much much better. Bob’s modelling found zero moisture build up even if the Cork climate had winter levels of RH for six months of the year. You just need a little bit of wind through the outer cavity, and it’ll dry out.

2. Obviously due to all the walls getting thicker by a quarter, lots of stuff had to be resized, especially the north curtain glazing which had to shrink in width. This improved heat losses obviously enough, and gave us a nice safety margin for PHPP. Indeed, we used some of those heat loss gains to make other windows a bit wider as we had the energy budget.

3. Previously, the steel frames had sat within the insulation as foam is rigid and detailing could keep the steel warm. My best understanding is that it isn’t wise to put steel through cellulose (I don’t entirely understand why, google says it doesn’t corrode steel and packs itself very snugly around steel), so our architect moved the steel frames to inside the airtight layer. Hence, we now have steel frames sticking out everywhere.

   It could be worse, we knew from the beginning that if we wanted vaulted ceilings, we could be getting exposed steel in return. So we’ve made the best of it, they’ll be painted oxide red and we’ve exposed them everywhere we can so there are clean lines, and you can see how it all hangs together.

4. As a result of the steel frames coming inside, we had to lose one of the windows in the reading area of the library mezzanine. Bob wanted one more solar panel anyway for safety margin in PHPP to ensure we’d definitely achieve Passive House Plus, so that window has been replaced with an additional solar panel, making thirty-seven in total.

Other than those changes, the house looks as it did before. When Stephen our architect updates all the feedback from all parties solicited to the first release of the draft final plans, I’ll present some screenshots here as barring any surprising changes coming from the structural engineer, that’ll be the final final house design.

Electrical schematics

As we are heading quickly towards the design being written in stone forever, there were a lot of loose ends which needed tidying up.

Firstly, I really needed to get the detailed electrical schematics finished. I kept putting them off, as they’re tedious and time consuming and I’m busy, but earlier tonight I made myself complete every room in the whole house, as I can tarry no further. I still have yet to do the distribution box design and load calculations from tying all the rooms together, but finally I have a schematic with everything every room in the house will have (electrically speaking, anyway). Here are some examples for (i) Master Bedroom (ii) Master Bedroom Bathroom (iii) Utility (which shows all the space heating stuff) (iv) Kitchen south:

The software I used is QElectroTech. It isn’t too great if I’m honest, there are loads of small annoying bugs and lots of stuff which feels either half arsed or half finished. But it’s free, and it does get the job done. I think the print renderings are especially not half bad, frustrating and tedious as it is to make them in the first place.

As all the socket and light placements have been fixed, I can now design exactly where to trunk the cabling once wire load calculations and distribution box design is done. All that is a few more hours work, the hard part was getting all the rooms done as now I can give a good approximation of what cable trunking will be needed and where, so we can tell the builder and structural engineer exactly where penetrations into the foundations will be e.g. if you need to lay a conduit for some underground cable.

The main entrance door

Another item I’ve been kicking down the road was the front entrance door. Nordan will be supplying all the glazing and doors apart from the entrance door, mainly because Nordan’s entrance doors do not look good. Indeed, their only passive spec entrance door very much looks like a school canteen door. I don’t know who designs their entrance doors, but they should replace them, whomever they are.

Munster Joinery’s only passive spec (u-value <= 0.8) door looks fine from afar, but when you get close to it it does not look good at all. Like most of the composite doors on the Irish market right now, they mould in a wood grain effect to the outer fibreglass, and then paint it with wood paint so from a distance, it does look fairly convincingly like wood. In fairness to MJ, they chose a rough wood grain unlike any of the competitors who have chosen a smooth wood grain. I actually prefer the rough wood grain, but it does make the door look like rough painted wood like you’d get on an eighteenth century cottage. And if it were just that, that would be fine, but unfortunately it also has all of MJ’s quality control issues with trim around windows – you’ll usually find at least one of the trims which doesn’t quite fit, isn’t quite flush, or the paint isn’t even. And this is even in their showroom models. It’s weird, it’s such a small thing to not screw up, but I guess they sell plenty of entrance doors with those issues and obviously the customers don’t care.

The other thing, of course, with painted fibreglass is the paint WILL come off after a few years and then you need to repaint it every few years thereafter. So as much as I appreciate them modelling wood as closely as possible complete with repainting it regularly, I’d rather less maintenance if possible.

Rationel and Palladio are two more sources of composite door with u-value’s below 0.8. Rationel’s website isn’t helpful at saying what door has what u-value, I kinda gave up and moved on to be honest (in fact, most of the big glazing and door manufacturers have REALLY lousy websites, they just show pictures of their products and present no detail which is actually useful like u-values or assembly breakouts). Palladio are of course Irish, they’re the biggest composite door manufacturer in Ireland out of their Limerick factory. Y’know, I really wish all glazing and door manufacturers were like Palladio, they have really comprehensive data about their products all online and all presented in an easy to browse, well categorised format. Every single installation option is shown complete with installation diagrams, assembly diagrams, u-values, materials, all from multiple angles. They are actually by far and away the best for an online presence of any glazing or door manufacturer I’ve seen in Europe. Really really good.

Unfortunately all their doors have a wood print on the fibreglass. I find it looks cheap, it’s too shiny and plasticky looking, and the pattern isn’t quite right. The rest of the door looks fine, no quality control issues like with MJ’s doors, and the u-values come in as low as 0.7 even with a pane. They’re a fine thick door too, 65 mm, which helps offset the lack of heft you get in composite doors as they’re basically 95% polyurethene foam.

Sometime around this point I kinda kicked the whole problem to touch as it was soaking up a lot of time, and I had more urgent issues. Last weekend we went to SelfBuild Limerick and Internorm were there. They had a rather nice looking entrance door with u-values well below 0.8 depending on which assembly you choise. Aha! I thought to myself, despite the lack of a Cork office, perhaps this is the solution?

Well, I went and got a quote after we got back. Now, steady yourself good reader, steel yourself for this: the quote was for €7,584 inc VAT delivered and installed. For a front door. When, the entire house’s passive grade glazing and no less than four other entrance doors comes in for €46k inc VAT delivered and installed. Which makes just the entrance door a whole one sixth of the total cost of all the other glazing and doors.

Needless to say we won’t be taking that option. I did check with the vendor if they had a mistake, and I was told that that thickness (93 mm) to achieve the sub-0.8 u-value was one of the most expensive Internorm has. And yes, it’s a rather nice door, and I appreciate it has three layers of aluminium in there for strength, and it’ll have as a result a nice bit of heft. It’s a superior door. But no way for us. Not in a million years for that kind of money.

So, that returns me to the unpalatable choices before me. I have found a potential light in the darkness however: Northern Ireland’s biggest composite door manufacturer Apeer also mostly produce wood grain effect on their fibreglass, but they do have one option without the wood grain effect, and here it is, along with their hilarious promotional video for it:

Yeah that’s some video for an entrance door, isn’t it? What they’ve done is use a splatter finish when moulding the fibreglass. Dead simple, but I think it works much much better. Yes when you actually touch the door and move it around, it’ll still feel fake, the door will be too light and the front it is plastic and no amount of splatter finish will eliminate that. But better I think to be pretending you’re something you’re not rather than claiming to be something you’re not.

U-value is < 0.8 installed, so it ticks the PH criterion. Door is 70 mm thick, so a little heftier than the Palladio door.

Let’s hope pricing is reasonable and there is a local Cork agent.

House build spend

It has been three months since the last house build spend update. This will be up to 1st January 2024:

• Spent: €243,207
• Committed to be spent soon: €14,374
• Current three month averaged spend rate: €7,293 per month

The three biggest ticket items in the past three months were: (i) Passive House certification fees (ii) Aliexpress on the Single’s Day heavily discounted sale, where I spent many thousands of euro buying all the lighting, dimmer switches, DC circuit breakers and lots of other odds and ends (iii) Final invoice for the Mechanical and Electrical design.

Last time I did an update on the house build spend I expected a build commencement in March. I would be surprised if we make April now, as the structural engineer is unlikely to get started before the end of January.

His fees will surely be the second largest item next time I do this end of March. I’m rather hoping that the largest fee will be the prepayment for doing the foundations, and the next time I do this house build spend update we will expect to break ground within weeks. Here’s hoping!

If I don’t draw down the mortgage by May, the offer will expire. I would expect that they will extend the offer, but I would prefer to not risk it especially when I have to front the costs of each stage in advance, and then recoup them from the bank after the work is signed off as complete. So if I fronted the cash, the mortgage offer expires before we can get the work signed off, and they then don’t renew the mortgage offer, then I am left in deep do doo .

#house