Green Building Forum - Getting SAP figure down Tue, 19 Dec 2023 05:30:50 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283727#Comment_283727 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283727#Comment_283727 Mon, 05 Oct 2020 20:51:05 +0100 jamesingram
A friends built a SIP house , 3G glazing , dont know exact wall, fabric thickness but I think its pretty low close to U=0.1 , individual MHRV in kitchen bathroom, PV on roof
Trouble is he's fittted a peat stove and it seems more problematically electric resistance heating rads. as a back up
though he wasnt expecting to use them much.
this has brought his SAP figure up too high for building regs sign off.
originally it was speced ASHP with UFH.
Anyone know the best bang for bucks to get it down.
Assessor told him he'd be better of with an oil boiler and rad with regards to SAP which seems odd given the carbon intensity of grid electric is falling to make it almost close the natural gas.
He's looking for a quick solution to resolve the issue.
I suggested just taking the electric rads out or switching to a couple of air/air heat pump units
thanks for any advice]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283733#Comment_283733 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283733#Comment_283733 Mon, 05 Oct 2020 22:18:50 +0100 neilu Your comment about the carbon intensity of the grid falling is correct however the current SAP method still reflects the grid of 7 years ago. This will only change when the new part L and new SAP come into force which is looking like it's gonna be a year away.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283735#Comment_283735 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283735#Comment_283735 Mon, 05 Oct 2020 22:28:09 +0100 neilu If there are multiple electric heaters around the house and only one stand alone peat stove then the SAP assessor may have entered the electric heaters as the main heating that heats most of the house and the peat stove as secondary heating that only heats the main living room.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283736#Comment_283736 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283736#Comment_283736 Mon, 05 Oct 2020 23:03:50 +0100 djh Posted By: jamesingramA friends built a SIP house , 3G glazing , dont know exact wall, fabric thickness but I think its pretty low close to U=0.1 , individual MHRV in kitchen bathroom, PV on roof
S/he should also be trying to get it airtight (i.e. have a target better than regs, ideally contractual) and as a result should be planning a full MVHR, IMHO. I think it can improve SAP.

he's fittted a peat stove

Where is the building? Peat doesn't sound like a sustainable fuel. I don't think it occurs in the SAP rules, so how is it dealt with? Can the stove burn wood? Maybe it's worth stating that as the fuel instead?

FWIW, Electricity as a fuel is bad for the existing SAP rating. I don't think the new rules are in force yet, except maybe in London? Specifying E7 electricity should help. But with decent insulation, ventilation etc it is possible to get a pass.

PS SAP is garbage, BTW, IMHO.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283749#Comment_283749 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283749#Comment_283749 Tue, 06 Oct 2020 12:26:27 +0100 GreenPaddy
The SAP person can tell him what has been entered, and how changing to a wood only stove would impact things. That caught me out once, even though the client only burned logs (never coal). So I found a Wood Only stove that looked identical, and sent that literature through to the SAP assessor and BSO. :shamed:

In previous projects, SAP assessors have always been advised to enter 50/50 for stove and electric heating, which was not a true reflection how it was be used, but since that can't be confirmed, the assessor was advised to enter 50/50.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283767#Comment_283767 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283767#Comment_283767 Tue, 06 Oct 2020 19:46:36 +0100 jamesingram He's on the outer hebrides and crofts so has rights to cut peats for personal use. in terms of population still cutting and use its sustainable as few still do.
Air test past Breg and was around 3 with full seal up.
He's pretty much finished everything and was just trying to sort out final paperwork when the SAP issue came up.
Early on he was let down by the initial design build outfit in various ways so has been doing what he can to get it finished with local labour as best he can. I've given him a bit of advice here and there ans did his PV system but my knowledge of SAP is minimal.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283770#Comment_283770 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283770#Comment_283770 Tue, 06 Oct 2020 20:22:25 +0100 WillInAberdeen
The target rate may set using any one of five heating systems: Gas+PV, LPG+PV, Oil+PV, ASHP or Wood Pellets.

IE not using high carbon heating such as either Peat or Electric Resistance heating.

You are free to use any heating you like in the actual dwelling, but you would have to reduce carbon in some other way to compensate. The target rate is set assuming U=0.17 walls and U=0.11 roof, so you'd need to be well below those levels to be allowed to use high carbon heating.

Best plan might be to see what heat source was specified to set the TER in the original Building Warrant application and install it, as specified?

Being the green building forum, we probably should encourage people to comply with the regs/stds, which are doing little enough to reduce emissions from newbuilds. If this were another forum, we could discuss dodges such as fitting a token ashp to get round building standards then ripping it out once the house is signed off, but that's not really what we're about..... !

Actually, they may find that the house uses so little heat that it's not worth the sweat of digging peat. Peat fires are culturally significant in NW Scotland, but like steam locomotives they are best appreciated in a museum!]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283773#Comment_283773 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283773#Comment_283773 Tue, 06 Oct 2020 21:07:10 +0100 jamesingram I think that's the situation , the expectation was little heat would actually be required due to the high insulation levels so investing in a ASHP seemed an expensive tick box exercise for something barely ever turned on.
Nothing much environmentally beneficial in installing kit that serves little purpose.
The occupants are use to living in uninsulated Croft cottages so can bear temperature way below what us southern softies can before needing to flick the heat switch on so as we can walk around in shorts a t-shirt whilst its baltic outside.
I'm all for good regulation but when the structure is unable to recognise builds that perhaps won't require heating it seems odd.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283777#Comment_283777 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283777#Comment_283777 Tue, 06 Oct 2020 22:35:35 +0100 djh Posted By: jamesingramI'm all for good regulation but when the structure is unable to recognise builds that perhaps won't require heating it seems odd.
Well if you accept that SAP/EPC isn't good regulation then life all becomes consistent again :devil:

Does it pass if he doesn't install the peat stove? And maybe installs PV instead?]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283779#Comment_283779 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283779#Comment_283779 Tue, 06 Oct 2020 23:53:19 +0100 WillInAberdeen
The Standard is intended to allow only lowish carbon houses, if they don't think they'd need low-carbon heating then the standard does allows them to insulate even more and then have minimal direct electric heating, IF that achieves the same CO2 overall. But it sounds like the house isn't insulated enough to pass with the electric heating.

Your suggestion of a small air-air heat pump(s) sounds good, because as you said the heating demand should be fairly low and they're not that expensive compared to retrofitting wet central heating. Relocate the stove into the sheep shed and light it while they are lambing.

When I moved to the North of Scotland I thought it was cold here, but now I think that everywhere else in the UK is uncomfortably hot, it's all about acclimatisation. We would roast if we lit a solid fuel stove in a well-insulated newbuild.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283781#Comment_283781 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283781#Comment_283781 Wed, 07 Oct 2020 08:30:20 +0100 GreenPaddy
Does it fail on Energy Efficiency or CO2 rating, or both?
SAP CO2/kWh rating for Coal (peat is not an option) = 0.4; elect = 0.5; logs = 0.02. I've rounded the numbers a bit but you can see coal is 20 times the CO2 rating for logs, and even with ASHP elect at say 25%, that would be 0.125.

It's unfortunate that your friend has built what is essentially a better than regs structure, but the fuel source for a very unusual setting causes it to fail, when lots of urban houses just scraping regs with G/ASHP and shoddily built, with much higher energy consumption pass. SAP is quite a blunt instrument, but we've a very big nut to crack, so it kind of needs to be blunt. That said, I don't really like the thought of burning peat, and not sure that any amount is sustainable, considering the millions of years it takes to replace it, but your friend appears to have made an effort to minimise his energy consumption (and generate), compared to his neighbours living in stone, single glazed, burning 50 times the amount of that same peat.

If your friend is willing to PM me his full SAP calc, I can have a quick look, and at least highlight the magnitude of the areas of failure to comply, and the extent to which changes would be required.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283785#Comment_283785 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283785#Comment_283785 Wed, 07 Oct 2020 10:17:00 +0100 RedDoor Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283797#Comment_283797 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283797#Comment_283797 Wed, 07 Oct 2020 16:53:52 +0100 WillInAberdeen
As was mentioned, the current version of SAP dates from a few years ago when direct electric heating was very high carbon. They've been talking for a while about updating SAP with changes in grid electricity. Once that happens, gas will become even less favourable than heat pumps etc. They are also planning to ban installing gas boilers, so maybe worth avoiding those as a dead end, which won't show up so well anytime the EPC is re done in future under the revised system.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283798#Comment_283798 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283798#Comment_283798 Wed, 07 Oct 2020 18:18:43 +0100 jamesingram
I couldnt agree more David. This is one reason (even with my limited knowledge of SAP) I find it annoying.

thanks for your comment everyone.

Update: after going to the SAP assessor to check he got the build and fabric details correct and armed with some of the info posted here, and on other connected posts on GBF, the property has now passed as is.
It appears the assessor probably didn't enter the correct data first time round. :neutral: a bit rubbish really.]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283799#Comment_283799 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283799#Comment_283799 Wed, 07 Oct 2020 18:30:41 +0100 jamesingram Adaptive thermal comfort - is a fancy way I've heard it described.
I think acclimatisation is a larger under considered solution to reducing energy use.
when i was up there fitting the PV in a hail storm in March i was freezing.
I got back to their rented accomodation and i was actually warmer outside,
where as they were happily sitting there with there thick jumps on in front of a open peat fire that barely warmed your face and made your back fill colder.
I gave them £20 and forced them to turn the electric storage heat on in my room
:bigsmile:]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283800#Comment_283800 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283800#Comment_283800 Wed, 07 Oct 2020 18:52:33 +0100 Ed Davies Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283802#Comment_283802 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283802#Comment_283802 Wed, 07 Oct 2020 19:12:17 +0100 jamesingram No idea of the science. There was a good short article in green building magazine years ago on the subject.
the 'adaptive' bit suggests you slowly get use to it, so slowly reducing heat should make it easier to adapt more comfortably one would think.
I asked my friend in the outer hebrides, whilst i was there, whether he think he'd adapted to the climate. His reply was "No, Im just use to feeling cold",]]> Getting SAP figure down http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283804#Comment_283804 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743&Focus=283804#Comment_283804 Wed, 07 Oct 2020 19:26:57 +0100 marktime
Absolutely no doubt that our bodies have acclimatised to the local ambient temperature.]]>