Green Building Forum - New homes standard

New homes standard

tony — Thu, 21 Jan 2021 22:29:48 +0000

Proposed

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Draft Future Homes Standard specification
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Floor U-value (W/m2.K) 0.11
External wall U-value (W/m2.K) 0.15
Roof U-value (W/m2.K) 0.11
Window U-value (W/m2.K) 0.8
Door U-value (W/m2.K) 1.0
Air permeability (m3/(h.m2) 5.0
Heating appliance Low-carbon heating (e.g. Heat pump)
Heat Emitter type Low temperature heating
Ventilation System type Natural (with extract fans)
PV None
Wastewater heat recovery No
y value (W/m2.K) 0.05

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ENERGY USE REDUCTION - ENERGY DEMAND REDUCTION Â should be the number one priorityÂ
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Floor U-value (W/m2.K)Â Â Â 0.1
External wall U-value (W/m2.K)Â Â Â 0.1
Roof U-value (W/m2.K)Â Â Â 0.1
Window U-value (W/m2.K)Â Â Â 0.7
Door U-value (W/m2.K)Â Â Â 1.0
Air permeability (m3/(h.m2) Â 1.0 or less
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ventilation with Heat recoveryÂ essential
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no more dormer windows unless U =0.1 for walls and roof
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same for extensionsÂ
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The elephant in the room seems invisible, action on the existing stock is needed (some use it leverage poorer standards for new build).
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New homes standard

Jonti — Fri, 22 Jan 2021 08:59:31 +0000

All of which is pretty academical so long as the enforcement of building quality is so lax.

New homes standard

tony — Fri, 22 Jan 2021 13:21:05 +0000

What enforcement?

New homes standard

HollyBush — Fri, 22 Jan 2021 14:20:12 +0000

Sorry I am a bit out of touch with this now - some thoughts:
1 - are these as built values at point of inspection, or in use by normal person? (Taping holes seems mad when testing, but I think that is done for example)

2 - is there anything to assess medium or long term compliance - thinking here that a normal home owner would expect the same after 10 years, but experience says a cheap door will warp, windows lose gas etc etc - something should cover the long term and help home owners maintain or have assurance how long these will last before degrading

Maybe a sperate conversation?

New homes standard

tony — Fri, 22 Jan 2021 14:44:13 +0000

LOL as built is always way short of as designed!! It is called 'the performance gap' there are no plans to close this, enforce or even check buildings other than with the existing statutory nspections that produce the gap in the first place,

some lip service but no teeth or carrots

New homes standard

jms452 — Sat, 23 Jan 2021 08:29:26 +0000

Nice summaries Tony - do you have the headlines for the current regs?

New homes standard

tony — Sat, 23 Jan 2021 16:52:41 +0000

Sorry no, I always aim to be a lot better than regs, they are minimum requirements and rarely met in practice.

New homes standard

SimonD — Sat, 23 Jan 2021 19:32:57 +0000

There was an interesting Guardian article aligned to this today.

https://www.theguardian.com/environment/2021/jan/23/buyers-of-brand-new-homes-face-20000-bill-to-make-them-greener

Interestingly they say that building a house to 'high energy efficiency standards' and using heat pumps instead of gas boilers would only cost and extra Â£4,800. I think that's got to be a rather optimistic figure.

I wouldn't argue against improving the energy efficiency of homes but I do wonder about whether the way we put together our standards is fit for purpose. I think we should be looking to design homes according to maximum energy consumption rather than u-values. If the homes use significantly more energy than designed, it's up to the developer to resolve the problem. Perhaps that might focus their attention on building better quality homes. U-values I think are just too theoretical.

New homes standard

tony — Sat, 23 Jan 2021 19:59:30 +0000

I like energy use reduction, the problem with maximum energy consumption is that it is a choice, the warmer it is the more energy is needed.

There is also sadly a problem with theoretical U-values and as built performance.

I foresee tax on energy consumption but difficult to do equitably

New homes standard

djh — Sat, 23 Jan 2021 20:12:34 +0000

Posted By: SimonDIf the homes use significantly more energy than designed, it's up to the developer to resolve the problem.

The problem there is the users. The energy used is controlled by the people that live there, and their criteria vary. Some people are happy to leave the heating off in most conditions and just put on extra layers and tolerate the temperature. Others, like me, have the irrational goal of keeping the temperature as close to but above 20Â°C at all times to meet an arbitrary standard. Still others insist on wearing a T-shirt and shorts at all times and maintaining the temperature to suit.

It's difficult to see why the developer should be responsible for that.

Certainly I'd support a move to test say the power required for the house to maintain a temperature of 10Â°C above ambient, but I expect there are lots of problems with trying to define that exactly.

New homes standard

WillInAberdeen — Sat, 23 Jan 2021 20:36:05 +0000

Should be easy to log the inside and outside temperatures and energy consumption for the first month/year of occupancy and compare (energy/DeltaT) against a legal standard?

As was mentioned, most of the UK's housing stock for 2050 has already been built. So wrangling about new build standards maybe missing the point, it's the renovation standards that matter. A surprising number of threads on GBF are about retro fit insulation, where they don't intend to comply with building regs/stds insulation values.

New homes standard

jms452 — Sat, 23 Jan 2021 23:20:58 +0000

Posted By: WillInAberdeenShould be easy to log the inside and outside temperatures and energy consumption for the first month/year of occupancy and compare (energy/DeltaT) against a legal standard?

Posted By: djhThe problem there is the users.

Both true - there are undoubtedly a lot of non performing houses out there (due to poor fabric) but looking out of the window and seeing our neighbour's patio doors open all day suggests that it's hard pin down the specific cause (i.e. user or poor build).

New homes standard

tony — Fri, 14 May 2021 17:14:58 +0100

Thanks for the update on future homes standard - just released

For me the wall U value is too high at 0.15

Air permeability needs to much lower amid mechanical heat recovery ventilation mandatory

I am disappointedÂ

tony

New homes standard

djh — Fri, 14 May 2021 20:18:36 +0100

Posted By: tonyThanks for the update on future homes standard - just released

I would like to thank you for posting the URL so I and everybody else wouldn't need to go looking.

But I too am disappointed.

New homes standard

tony — Fri, 14 May 2021 20:23:56 +0100

https://www.elmhurstenergy.co.uk/analysis-of-the-future-homes-standard-consultation-outcome

New homes standard

djh — Fri, 14 May 2021 20:31:31 +0100

Thanks

New homes standard

djh — Sat, 15 May 2021 13:49:17 +0100

Another aspect I'm disappointed about is the authorization of low pressure Pulse testing of airtightness

https://buildtestsolutions.com/air-leakage-testing/pulse/

The idea that knowing the average loss to make it easier to calculate EPCs is more important than finding faults in the construction at a time when they can be fixed is typical government idiocy, IMHO.

New homes standard

tony — Sat, 15 May 2021 16:41:57 +0100

Nutts

New homes standard

Jonti — Sat, 15 May 2021 21:12:55 +0100

Posted By: djhAnother aspect I'm disappointed about is the authorization of low pressure Pulse testing of airtightness

https://buildtestsolutions.com/air-leakage-testing/pulse/" rel="nofollow" >https://buildtestsolutions.com/air-leakage-testing/pulse/

The idea that knowing the average loss to make it easier to calculate EPCs is more important than finding faults in the construction at a time when they can be fixed is typical government idiocy, IMHO.

It is a sign that they think the result is the relevant/important thing and are not worried about where the problem is if there is one. I suspect this change has been pushed for by the big building companies as they want quick and cheap ways to test.

Just imagine the money that could be saved if they let school kids mark their own exams!!!

New homes standard

tony — Sun, 16 May 2021 07:05:58 +0100

This system seems to maximise the viscosity influences of air moving through cracks and gaps.

My bottom line is that we need more widespread simple testing .

Downside is that it wonâ€™t put a stop to air leakage and thermal bypass behind dot and dab ðŸ˜

New homes standard

revor — Sun, 16 May 2021 08:51:40 +0100

My take is we should not need to test we should be building quality in. We know how it should be done. Problem is those in the industry cannot be bothered to train crafts people properly, the underpinning knowledge as to why things need to be done is not there, plus the not caring attitude and chasing the bottom line. A few hundred yards from me a little estate of affordable PH have been built. Part way through they realised it was costing too much and they tried to save money on the build and changed the construction approach. One of the things they did they made their own roof sips panels with OSB and PIR and when they ran out of the special tapes for air tightness they used duct tape. They leaked like a sieve when pressure tested. 1st few house were good. Got the info from BCO, and a slater who did the roofs both who were on my build so is not anecdotal evidence. Part of the houses are timber clad poorly treated/ finished and now 4/5 years later look a real mess as coating has weathered away down to bare wood.

New homes standard

djh — Sun, 16 May 2021 11:15:25 +0100

Posted By: revorMy take is we should not need to test we should be building quality in. We know how it should be done.

Right, it should be done the way PHI specify. That is, by testing and auditing. You can't 'build quality in' without carefullychecking that everything has been done properly and successfully. And that includes airtightness testing every house properly. Specifically to check that the seals hold in gale force winds with both positive and negative internal pressures.

A few hundred yards from me a little estate of affordable PH have been built.

From what you say, not they haven't been built as certified PH. To do so, they would have had to produce the bill of materials and photos showing what tapes were installed, what insulation was fitted (and how much of it) etc. And they would have had to produce airtightness test results for every dwelling showing < 0.6 ACH.

Posted By: tonyMy bottom line is that we need more widespread simple testing .

Downside is that it wonâ€™t put a stop to air leakage and thermal bypass behind dot and dab ðŸ˜

We need more widespread testing, yes. It needs to be reproducible. Not necessarily 'simple'. And yes, proper testing will put a stop to air leakage behind dot and dab. Thermal bypass is stopped by examining the design drawings and demonstrating with evidence that it's been built as designed. i.e. the PH process.

New homes standard

tony — Sun, 16 May 2021 13:35:48 +0100

Thermal bypass can still happen when following robust details, the rooms are airtight but the building insulation is outside the air sealed envelope, outdoor air getting past or through the insulation but not into the building. Whistling around behind dot and dabbed linings on internal and external walls, all too common still.

New homes standard

djh — Sun, 16 May 2021 17:57:51 +0100

Posted By: tonyThermal bypass can still happen when following robust details, the rooms are airtight but the building insulation is outside the air sealed envelope, outdoor air getting past or through the insulation but not into the building. Whistling around behind dot and dabbed linings on internal and external walls, all too common still.

Can you give an example of a certified passivhaus that shows this problem?

New homes standard

Jonti — Sun, 16 May 2021 18:09:03 +0100

Posted By: revorMy take is we should not need to test we should be building quality in.

Yet nobody who buys a house from one of the big builders ever check what sort of a track record the company has for quality build. The house building industry in the UK is a mess with the vast majority of houses built being of poor quality. The problem is nobody who could make a difference (builders, politicians, house buyers) is bothered by it. The best way to get a quality build is do your homework and get a smaller building company and do the supervision yourself but make sure you know what you are looking at.

New homes standard

tony — Sun, 16 May 2021 19:39:10 +0100

No examples of PH with thermal bypass but loads of homes have major problems even brand new ones

New homes standard

djh — Sun, 16 May 2021 20:24:51 +0100

Posted By: tonyNo examples of PH with thermal bypass but loads of homes have major problems even brand new ones

I know but that is exactly the problem with a broken building control system! There's no such thing as 'robust details' in the PH methodology. Nor is there in the UK system any longer AFAIK. :)

+1 to what Jonti said. But there's no way to apply that to the majority of builds or even to a substantial minority.

New homes standard

Jonti — Mon, 17 May 2021 09:09:39 +0100

djh,

the only way to improve the lamentable standards would be to have each individual build go through the full range of building standard checks. What is sad is I recon it would add just Â£250 to Â£300 to each new build house to do so but no one seems bothered.

New homes standard

djh — Mon, 17 May 2021 10:26:47 +0100

Posted By: Jontidjh,

the only way to improve the lamentable standards would be to have each individual build go through the full range of building standard checks. What is sad is I recon it would add just Â£250 to Â£300 to each new build house to do so but no one seems bothered.

I would happily vote for that, plus changing the rules to at least allow if not mandate PH as the standard instead of UK regs.

New homes standard

Artiglio — Mon, 17 May 2021 13:03:14 +0100

Posted By: Jontidjh,

the only way to improve the lamentable standards would be to have each individual build go through the full range of building standard checks. What is sad is I recon it would add just Â£250 to Â£300 to each new build house to do so but no one seems bothered." title="">

Whilst it would most certainly raise standards, i really canâ€™t see that you could inspect, verify ,record and certificate all the necessary details for Â£300, thatâ€™s not going to cover more than a days labour let alone the overheads. Unless it just ends up as a tick box exercise carried out by the lowest bidder in which case it achieves nothing.