Green Building Forum - Future heating of old houses Tue, 19 Dec 2023 06:24:23 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300934#Comment_300934 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300934#Comment_300934 Fri, 24 Mar 2023 17:23:16 +0000 PeterWat
Background is living in a 1920s house - detached, semi-rural position, mostly solid brick walls; double glazed and some loft insulation; suspended timber ground floors. So far, bills for our gas CH/gas cooking/gas DHW are still not horrendous. Two advantages we have are south facing main windows, so a lot of solar gain; and one small woodstove, costing nothing to run (as we have a firewood source, coppiced and processed ourselves, seasoned when cut, stored for minimum 2 years under cover and well ventilated).

We have so far resisted going for expensive EWI and floor insulation. Partly because this would be very difficult and disruptive (and would cover up period features), and partly because we may be moving anyway; and the trend locally is for developers to demolish and rebuild (or gut and massively extend) many older houses that come on the market. So any retrofit insulating we did might have a very short life.

All that said, our gas boiler is over 15 years old and the decision is either (1) replace like with like; or (2) spend more on a heat pump. The latter would be doing the "right" thing - by current national advice - but is it?

On (2) all the usual advice says no - not worth doing unless the house is super-insulated as well.

Am wondering, however. In our situation, might it be worth considering an ASHP that would be considered undersized; keeping the existing radiators; and topping up heat in cold weather by plug in convector heaters? An expensive option, but would it remain so?

In the UK, conventional wisdom (at least, in the chattering classes) suffers from a deeply ingrained belief (dating from the 1950s) that gas heating is cheap, electric is expensive. I wonder though if this will soon be all wrong? Solar and wind power costs are tumbling but electricity seems likely to stay expensive due to the high costs of maintaining back-up generation (or energy storage) for periods of low generaion by renewable sources. On the other hand, the costs of fossil fuel power (or natural gas replacement by hydrogen) may get even more expensive. (For climate reasons they certainly ought to be).

Alongside all that, construction materials- and wage- inflation is simultaneously making effective insulation much more expensive.

So in future, might it become a valid strategy to leave some older, period houses poorly insulated, use a smallish ASHP for background heat, and bite the bullet of topping up with old-tech plug in heaters to heat key rooms on cold days?

Obviously not the ideal solution from a climate perspective - but in the (post mid-century) future we may have surpluses of renewable electricity, with significant consequences for relative prices.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300935#Comment_300935 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300935#Comment_300935 Fri, 24 Mar 2023 18:04:08 +0000 fostertom Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300936#Comment_300936 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300936#Comment_300936 Fri, 24 Mar 2023 18:25:14 +0000 borpin
If you feel the cost of insulation is wasted effort, I'd suggest a HP is more so.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300938#Comment_300938 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300938#Comment_300938 Fri, 24 Mar 2023 19:04:12 +0000 Peter_in_Hungary
Meanwhile I would run the gas boiler until it is no longer viable, stuff a bit more insulation in the loft and concentrate on draft proofing i.e. do the easy quick wins now and put off any big expenditure until you know where you are going.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300939#Comment_300939 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300939#Comment_300939 Fri, 24 Mar 2023 19:59:40 +0000 fostertom Posted By: PeterWatvalid strategy to leave some older, period houses poorly insulated, use a smallish ASHP for background heatBut could you resist turning the HP's flow temp up, make the rads run hotter than tepid? If you do, CoP plummets.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300940#Comment_300940 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300940#Comment_300940 Fri, 24 Mar 2023 20:25:25 +0000 DamonHD https://es.catapult.org.uk/news/heat-pumps-shown-to-be-three-times-more-efficient-than-gas-boilers/

"High Temperature ASHPs had comparable efficiencies to Low Temperature ASHPs, indicating that they are a viable solution to reduce home retrofit requirements."

From a few days ago.

Rgds

Damon]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300941#Comment_300941 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300941#Comment_300941 Fri, 24 Mar 2023 20:27:46 +0000 philedge Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300942#Comment_300942 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300942#Comment_300942 Fri, 24 Mar 2023 21:00:54 +0000 djh Posted By: DamonHDhttps://es.catapult.org.uk/news/heat-pumps-shown-to-be-three-times-more-efficient-than-gas-boilers/

"High Temperature ASHPs had comparable efficiencies to Low Temperature ASHPs, indicating that they are a viable solution to reduce home retrofit requirements."Looks interesting but I have no idea what the difference is between Insights and Performance Data Analysis :cry: Plus the web page is rather bizarre in terms of how it handles forms etc, so I think I'll just wait until the final report comes out. Hopefully somebody will remind us when it does. :bigsmile:]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300944#Comment_300944 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300944#Comment_300944 Fri, 24 Mar 2023 21:56:57 +0000 tony
Loft insulation 400mm+

I live without a formal heating system, bit of extra heat used during cold snaps.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300947#Comment_300947 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300947#Comment_300947 Sat, 25 Mar 2023 11:04:29 +0000 fostertom Posted By: DamonHDHigh Temperature ASHPs had comparable efficiencies to Low Temperature ASHPsComparable - can mean 'compare the numbers and they're terrible'. But here Comparable claims to mean 'almost as good'. However, would it be true to say that in fundamental theory High will always be worse than Low by the ratio of some power of the temp difference, only slightly(?) nuanced by tech cleverness like using a different refrigerant?]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300948#Comment_300948 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300948#Comment_300948 Sat, 25 Mar 2023 12:56:50 +0000 DamonHD
But weather compensation meant that the HT were actually running as LT much of the time.

Also, the variation in SCoP caused by installation variation is large enough to make the HT/LT in-use CoP barely significant. This variation needs fixing.

Rgds

Damon]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300949#Comment_300949 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300949#Comment_300949 Sat, 25 Mar 2023 13:04:44 +0000 WillInAberdeen
The heat input comes from latent heat of the refrigerant, and the electricity consumed by the compressor. New high temperature heatpump models have better-suited refrigerants with more latent heat, and better-suited compressors that use less electricity.

Once you've installed your heatpump, you can't change the refrigerant, so to get to higher temperatures you have to work the compressor harder. So they use weather compensation to only work the compressor just as hard as necessary, the report suggests setting up the weather compensation is key to getting good CoP. That requires skilled installers, which we don't have many of.

Edit: crossed with Damon, thanks for the link!]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300950#Comment_300950 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300950#Comment_300950 Sat, 25 Mar 2023 13:49:36 +0000 fostertom Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300951#Comment_300951 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300951#Comment_300951 Sat, 25 Mar 2023 14:43:29 +0000 WillInAberdeen
Now on our next project, the world has changed. Renewable cheap heat is very much in view with electric heatpumps, whereas the climate impacts of new-building is much clearer. So retaining existing buildings with sensible insulation seems the new greenest thing. Sensible in our case means lots of wool in the loft and slung under the floors, draughts hunted and stopped, but no hurry for EWI or replacement windows.

Our recent foray into heatpumps crashed with the shortage of installers around here. I wanted something basic like the OP, but the skilled installers are driven by MCS to install oversized gold-plated systems that are guarantee-able to work in all weathers, so we fell out. Will try again as more installers are available.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300952#Comment_300952 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300952#Comment_300952 Sat, 25 Mar 2023 21:06:03 +0000 djh Posted By: WillInAberdeendraughts hunted and stoppedTo the extent that it might be called 'airtight'? In which case the phrase 'ventilate right' might apply?]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300953#Comment_300953 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=300953#Comment_300953 Sat, 25 Mar 2023 22:29:48 +0000 Mike1 Posted By: PeterWatWe have so far resisted going for expensive EWI and floor insulation. Partly because this would be very difficult and disruptive (and would cover up period features), and partly because we may be moving anyway; and the trend locally is for developers to demolish and rebuild (or gut and massively extend) many older houses that come on the market.Maybe that's the solution - sell to a developer and move out (unless you want to turn developer yourselves).]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302064#Comment_302064 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302064#Comment_302064 Tue, 20 Jun 2023 14:15:29 +0100 lineweight
Old house, ground floor straight onto the ground. There will be some extensions which can be insulated properly (including the floors) and we will do a mixture of internal and external insulation to get the envelope of the old house reasonably well insulated.

At the moment it has a gas boiler & conventional radiators. The boiler is relatively new and has enough capacity that we could add radiators in the space in the extensions into the system.

So that would be the easiest option: keep the gas boiler and add a couple of radiators.

But would we be missing the opportunity - while doing major renovations - to future-proof the heating system? Of course none of us really know what will happen over the next 10-20 years. Maybe the price of electricity relative to gas will drop. Maybe heat pumps will become quieter and smaller. Maybe the gas system will transition to Hydrogen (seems a bit of a long shot). Maybe the return on investment on solar panels will improve.

We could stick with the gas boiler for now, and say that maybe in the future (when it next needs replacing, say) we could review the option of replacing it with a heat pump based system. The radiators would continue in use, it would just be the boiler that would get swapped out. Is that basically feasible?

Finding a location for an air source heat pump would be tricky (very tight urban site). Should we be looking into ground source heat pumps, seeing as the right time to put one in would be when the site is getting dug up anyway? But then that implies ditching the gas boiler at this stage.

Putting off a decision about solar panels seems easier - because it is moderately independent of the exact nature of the heating system. As long as the heating continues on gas, solar panels would be of minimal benefit. Adding solar panels could be considered if and when a transition to electric heating was being considered.

There’s also the question of whether or not to use underfloor heating in the extensions (it’s not viable in the main house, due to the amount of digging out that would be required). Potentially it could be a wet system that would run off the boiler, along with the radiators (although I need to check out the technicalities of that). And if the boiler were switched for a heat pump in the future, the underfloor heating could continue to work. But if there was a future switch to solar panels would that be an inefficient way to do it, with electricity heating up water for underfloor pipes when it could just directly heat up a dry system instead?

Lots of slightly vague questions. It feels very hard to make the right decision with so many unknown variables.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302074#Comment_302074 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302074#Comment_302074 Tue, 20 Jun 2023 17:37:50 +0100 djh Posted By: lineweightPutting off a decision about solar panels seems easier - because it is moderately independent of the exact nature of the heating system. As long as the heating continues on gas, solar panels would be of minimal benefit. Adding solar panels could be considered if and when a transition to electric heating was being considered.Solar panels and space heating are mutually orthogonal. There's minimum output from solar panels at the time you need space heating, so it's simplest to assume there's no interaction, and it's not far wrong as assumptions go. You can balance your winter electrical heating with solar panels on an annual basis, but you can do it equally with part-ownership of a wind turbine and the generation pattern for that much more nearly matches the heating season.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302077#Comment_302077 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302077#Comment_302077 Tue, 20 Jun 2023 18:03:00 +0100 lineweight Posted By: djh
Posted By: lineweightPutting off a decision about solar panels seems easier - because it is moderately independent of the exact nature of the heating system. As long as the heating continues on gas, solar panels would be of minimal benefit. Adding solar panels could be considered if and when a transition to electric heating was being considered.
Solar panels and space heating are mutually orthogonal. There's minimum output from solar panels at the time you need space heating, so it's simplest to assume there's no interaction, and it's not far wrong as assumptions go. You can balance your winter electrical heating with solar panels on an annual basis, but you can do it equally with part-ownership of a wind turbine and the generation pattern for that much more nearly matches the heating season.

Things might be different 10+ years hence, though. For example battery storage technology might develop - whether that's at an individual dwelling level, or supply grid level with in/out tarrifs to match.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302079#Comment_302079 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302079#Comment_302079 Tue, 20 Jun 2023 20:48:14 +0100 fostertom Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302081#Comment_302081 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302081#Comment_302081 Wed, 21 Jun 2023 10:31:17 +0100 Mike1 Posted By: lineweightBut would we be missing the opportunity - while doing major renovations - to future-proof the heating system? ...The radiators would continue in use, it would just be the boiler that would get swapped out. Is that basically feasible? ...There’s also the question of whether or not to use underfloor heating in the extensions (it’s not viable in the main house, due to the amount of digging out that would be required).
The best way of future proofing the heating system would be to put wet underfloor heating everywhere you can. That provides low-temperature heat that can be provided from any current or future fuel source. As well as providing more even temperature gradients within the rooms and more free wall space.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302085#Comment_302085 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302085#Comment_302085 Wed, 21 Jun 2023 10:54:18 +0100 djh Posted By: lineweightThings might be different 10+ years hence, though. For example battery storage technology might develop - whether that's at an individual dwelling level, or supply grid level with in/out tarrifs to match.
Posted By: fostertomOr just much more efficient panels (W/m2) and/or much cheaper so more area of, so even in winter there's significant output, esp with lo-demand buildings. All things that are bound to come, tho too slowly at present. Non-silicon/paint-on/transparent panels, well they'll no longer be called panels ...
Anything could happen, of course, but then again it might not :bigsmile: Nothing's going to change the fundamentals of how much energy comes to the surface from the sun in winter though. Short-term storage doesn't help either; you need storage for several months. So especially when you add the DHW demand to the space heating demand, I stand by what I wrote. Any possible developments more than ten years out aren't worth taking much account of IMHO.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302088#Comment_302088 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302088#Comment_302088 Wed, 21 Jun 2023 11:36:03 +0100 fostertom Posted By: djhAnything could happen, of course, but then again it might not ... Any possible developments more than ten years out aren't worth taking much account of IMHOFair enough, but though
Posted By: djhNothing's going to change the fundamentals of how much energy comes to the surface from the sun in winter
is true, the fundamentals of how much space heating a building will demand may (10yrs out) change relative to how much solar electricity is commonly available to each building on a current basis even during poor winter insolation. Demand may fall drastically while collection are and/or efficiency may rise drastically. That is the current trajectory, which exists despite current turmoil and conflict of interest, so it does seem a fair bet for 10yrs on.]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302128#Comment_302128 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302128#Comment_302128 Fri, 23 Jun 2023 21:06:13 +0100 cjard
Has to be so cold that the COP of the heat pump dips below 1 before that makes sense...

"Should we be looking into ground source heat pump"

They need even more space than an ASHP. Put the ASHP on a wall so you can walk under it?]]> Future heating of old houses http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302185#Comment_302185 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17794&Focus=302185#Comment_302185 Wed, 28 Jun 2023 11:25:10 +0100 Artiglio