iiinova — where your digital self keeps evolving

Es Tresidder @estresidder.bsky.social · 03/07/2026

Been off social media for a while for various reasons. Hoping to be able to engage a bit more from now on. Here’s a blog I wrote about two recent site visits: www.highlandpassive.com/how-big-is-y...

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Es Tresidder @estresidder.bsky.social · 03/07/2026

Sorry, been off most social media for a while. How can I help?

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Es Tresidder @estresidder.bsky.social · 21/04/2025

That’s encouraging, thanks Robert. Heated seats should also reduce need for cabin heating, although on our Leaf we often need heating to keep windscreen clear.

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Es Tresidder @estresidder.bsky.social · 21/04/2025

Hi Rob. Sorry for slow reply, not been on socials much. Don’t know if any examples off the top of my head. Happy to help if I can, drop me an email.

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Es Tresidder @estresidder.bsky.social · 21/04/2025

Had nearly decided on an MG5 as our new car, but just learnt it doesn’t have a heat pump. Some models do have heated seats though. Interested to hear folks experience of this EV or others without heat pumps to get a picture of how much more of an impact on range that makes in winter. Thanks 🙏

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Es Tresidder @estresidder.bsky.social · 21/04/2025

Soz not been on Bluesky much. Found a small amount of asbestos in one place. Didn’t test concrete.

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Es Tresidder @estresidder.bsky.social · 02/03/2025

With PV I expect our electricity bills for everything, including charging an EV, to be ~zero. 💪 *possibly won’t cover the standing charge.

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Es Tresidder @estresidder.bsky.social · 02/03/2025

This includes an increase in average internal temps (from 17° to 20°). Couple these sort of demand reductions with well designed and commissioned heat pumps and you get super low energy bills; our heating and hot water comes in at less than £170 a year before factoring in PV 🌞

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Es Tresidder @estresidder.bsky.social · 02/03/2025

@aecb.bsky.social retrofit standard and #Passivhaus EnerPHit typically deliver much higher reductions in heat demand than that. I’m working on half a dozen timber-frame deep retrofit projects, and an 80% reduction in annual heat demand is typical.

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Es Tresidder @estresidder.bsky.social · 02/03/2025

This is excellent from @richardlowes.bsky.social. Absolutely agree that super deep retrofit isn’t always appropriate, but one thing I’d say here is that the heat demand reductions mentioned here as the top end of what can be achieved (40-50%) are lower than what can be achieved at the top end.

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Es Tresidder @estresidder.bsky.social · 25/01/2025

How did storm Eowyn impact the heat demand in our #EnerPhit retrofit? Looks like hardly at all! Gale force 💨 yesterday, calm today. ⚡️demand for heat a bit higher today (colder). Suggests impact of even gale force 💨 is small/negligible due to good wind-tightness & excellent airtightness. #Passivhaus

Electricity demand for our air to air heat pump (blue), internal temperature (black) and external temperature (purple) for the 24th January, during storm Eowyn. Average outdoor temperature 5.4°C and total electricity use 6.7 kWh.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

Didn't really feel this episode was pushing back against MVHR, just highlighting that it needed to be done well. Did you?

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Es Tresidder @estresidder.bsky.social · 23/01/2025

I’m not sure what the deal is with condensate on those single room units, I’ve never had one on a project, see what the manual says.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

- Clean filters (change every 6 months or more often if very polluted area) - cross-talk attenuators if using branched ducting rather than radial.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

- Quiet units, mounted in a room where the noise won’t matter, ideally on an external wall (see bit about duct lengths). -silencers between unit and rooms (for both supply and extract) - appropriate ventilation rates - high quality ducting sized to allow low air speeds in ducts and as direct as poss

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Es Tresidder @estresidder.bsky.social · 23/01/2025

Some other things I’ve seen and heard of being done wrong, thankfully none of these on my projects: - looping excess ducting in the loft to reduce noise transfer to rooms - failing to put a downslope on pipe from condensate drain, causing unit to flood (bearings needed replacing)

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Es Tresidder @estresidder.bsky.social · 23/01/2025

I’d always recommend getting a Passivhaus certified unit (quieter, more efficient fans, realistic efficiency %s) and getting it designed, installed and commissioned to Passivhaus requirements, even it’s a 🏡 that is going nowhere near PH standard in other areas. Quality assurance v important here.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

Even if the ducts are super short they still need to be well insulated (I’ve seen them long *and* uninsulated), otherwise they are a risk for condensation and heat loss.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

Even with the best (43mm EPS) pre-insulated ducts on the market each additional metre added to both ducts reduces the total system efficiency by ~1.3%. If your unit is in the middle of your house, 5m from an external wall, then suddenly your 90% efficient unit is only 83% efficient.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

One thing not mentioned in this podcast but that I’ve seen done loads, is the length of ducts between the MVHR unit and the thermal envelope. If the unit is inside both the fresh air and the exhaust air ducts are cold, and heat losses from the building to them are significant.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

There’s loads of evidence that shows the conventional way of ventilating homes (trickle vents, extract fans and opening windows) leads to poor air quality, poor comfort and high energy use. Done well, MVHR will radically improve all of these, but done badly it can be a disaster.

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Es Tresidder @estresidder.bsky.social · 23/01/2025

Useful podcast here on some things that can go very wrong with MVHR. I like to think of MVHR as a bit like pneumatic tyres on a bike. Installed properly and maintained they are *way* better than solid tyres, but if you don’t maintain them they are even worse (try riding a bike with a flat tyre).

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Es Tresidder @estresidder.bsky.social · 16/01/2025

Thanks. Mistake was I had ‘the’ at the start of the address. Have resent now. Cheers, Es

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Es Tresidder @estresidder.bsky.social · 15/01/2025

Share your concern for the horizontal ones (suspect they need regular cleaning). Vertical ones are just a vertical pipe within a pipe, so shouldn’t be any more likely to block than a normal down pipe.

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Es Tresidder @estresidder.bsky.social · 15/01/2025

Here’s the PHPP calc for mine. 69% efficient unit ends up as 56% efficient for 5min shower. Also worth factoring into the payback calc: - does it allow you to choose a smaller tank. It did for me, and that saved £200 - might allow you to do more/all of your water heating during cheap ⚡️.

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Es Tresidder @estresidder.bsky.social · 15/01/2025

There’s a bit more to it than just the HR efficiency, also depends on length of drain pipes between shower and HX, and whether connected to cold side of shower and cold feed to tank or just one or the other, so system efficiency ends up less than heat exchanger efficiency.

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Es Tresidder @estresidder.bsky.social · 15/01/2025

Several of the units are Passivhaus certified so solid efficiency data from which you can do the calcs on whether they stack up economically. My vert set up more than halves the energy requirement for a typical shower.

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Es Tresidder @estresidder.bsky.social · 15/01/2025

Yes, you can do it, it’s what I have in my house, with the showers in neighbouring upstairs rooms. What Alan says plus check the flow rates of the two showers don’t exceed the recommended total for the HX.

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Es Tresidder @estresidder.bsky.social · 15/01/2025

Hi @evanhd.bsky.social, I tried to send an email to the email address provided at the end of the flats podcast but got an address not found failure. Could you let me know the email address please? Thanks!🙏

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Es Tresidder @estresidder.bsky.social · 06/01/2025

Cool, is there a way for me to see a dot and work out which unit it is on Heat Pump Monitor?

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Es Tresidder @estresidder.bsky.social · 06/01/2025

Good work John! 👏 I didn’t know there were heat pumps in the Cairngorms getting an SCOP>4. I’ll have to do some digging on those. Although I think the location is not quite right! I’ve stayed at the Hutchinson hut, pretty sure it doesn’t have a heat pump!

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Es Tresidder @estresidder.bsky.social · 04/01/2025

Good to read this. Whereabouts is your house Stuart?

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Es Tresidder @estresidder.bsky.social · 27/12/2024

House will be lower than the car is my guess. Definitely if you are factoring in the PV. Possibly close if you are not.

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Es Tresidder @estresidder.bsky.social · 21/12/2024

Useful, thanks Robert. Have you been happy with the car so far?

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Es Tresidder @estresidder.bsky.social · 21/12/2024

Right, side project for the Christmas season is to source a new (second hand) #EV. Current thinking is an MG5. Needs to be able to take a tow bar for a bike rack. I think the more recent ones can, is there a year that doesn’t that I shouldn’t go further back than? #electricCars #EVs

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Es Tresidder @estresidder.bsky.social · 25/11/2024

Excellent, good to see projects getting monitored. Yours or a clients?

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Es Tresidder @estresidder.bsky.social · 24/11/2024

Is the error really obvious when it happens, or does performance slowly deteriorate? Just wondering what I should be watching out for with my air to air (mini split).

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Es Tresidder @estresidder.bsky.social · 23/11/2024

By my calcs we’re £145 for A2A plus £30 for HPWH. I think your calc is for Intelligent Go, which is 7p/kWh for 7h overnight. We don’t have an intelligent enough car for that so we’re on standard Go which is 9p/kWh for 4h a night. Hopefully we’ll get a more intelligent car soon!

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Yeah I’ve got an inline meter. Wasn’t that expensive and simple job with basic plumbing skills I think.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

You can monitor the HW energy usage quite easily though, I just use a plug in meter for that. Harder to separate out the towel rails from that though.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Do you have monitoring of your A2A electricity use Juraj? I'd be interested to see your stats too. I've got temp monitoring in 3 key rooms now too, so I'll post something about that when I get time. Recent cold spell was a good test of only delivering heat in one room!

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Chuffed though I am, I doubt it. A moderately sized new build Passive House with a heat pump working reasonably well should certainly use less electricity for space heating than we do, so it would just need an efficient hot water system as well. Get monitoring your systems people!

Daily average outdoor air temperature (purple, °C) and total daily electricity usage by the air to air minisplit (blue, kWh) for the year from 14 Nov 2023.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

In fact, our house was recently recognised as having the lowest heating costs on the heatpumpmonitor.org site (lnkd.in/e27W9Dne), which raises an interesting question, could we have the lowest heating costs in the UK?

heatpumpmonitor.org

HeatpumpMonitor.org

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Total space heating electricity usage (some of which is actually heat for the hwhp): 756 kWh Total water heating electricity usage: 336 kWh Total hot water usage: 18,000 litres (about 50 per day). Mostly at 52°C, but we boost to 60°C when we have visitors and need the extra capacity.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Relatively low hot water usage for now, I expect this to change as the children get older! The last three points mean that our hot water reheat times are quick enough that all the hot water heating is during the 4 cheap hours per night.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

The hot water heat pump has a reasonable efficiency all year round, since it is 'stealing' heat from the house at ~20°C.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

Our hot water demand is low because we have shower-water heat recovery, very efficient (radial 10mm) distribution and 6l/min showers. Surprisingly the showers are among the nicest I've used.

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Es Tresidder @estresidder.bsky.social · 23/11/2024

We've been able to demand shift quite successfully. 52% of the electricity used by the air to air heat pump was in the middle four hours of the night when the electricity is just 9 p/kWh (although the rest was at 29 p/kWh).

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