Green Building Forum - heating options for eco retrofit Tue, 19 Dec 2023 08:38:42 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300160#Comment_300160 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300160#Comment_300160 Tue, 07 Feb 2023 10:10:36 +0000 maxsm
Are there any radiators out there that we could connect to a gas boiler in the short/mid term and then ASHP in future? If yes, is there anything we should be aware of when sizing the radiators?

Thanks in advance for any help]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300169#Comment_300169 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300169#Comment_300169 Tue, 07 Feb 2023 12:41:09 +0000 djh
Talk to whoever is designing your extension and retrofit about what you want to do and try to find a heating specialist in your area who understands ASHP and retrofitting them into a system such as yours. Between them they should be able to design a suitable upgrade.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300172#Comment_300172 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300172#Comment_300172 Tue, 07 Feb 2023 13:09:47 +0000 owlman Also look at simple electric towel rad in the bathroom. I made my own from a standard rad. with a thermostatic immersion insert. It works great and is on from 0500 to 2300 daily. the standard TRV bathroom wet rad rarely gets above lukewarm, if at all.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300175#Comment_300175 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300175#Comment_300175 Tue, 07 Feb 2023 13:41:59 +0000 lngn2
As an aside, how are you planning to get enough floor insulation in without digging out?]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300176#Comment_300176 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300176#Comment_300176 Tue, 07 Feb 2023 15:35:31 +0000 philedge
If youre not insulating the floors then don't use UFH as much of the heat output will be lost to the ground.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300177#Comment_300177 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300177#Comment_300177 Tue, 07 Feb 2023 15:46:16 +0000 fostertom heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300180#Comment_300180 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300180#Comment_300180 Tue, 07 Feb 2023 16:13:29 +0000 jamesingram Perhaps 1 or 2 Air to air unit and an electric towel rad will do the jobv for when it drops below 5 outside.
An additional cheap plugin electric fan heater for really cold days.
HW will have to be an electric immersion.
Invest all the money you'd be spending on the heating system in the fabric and PV to cover the HW and background usage]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300185#Comment_300185 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300185#Comment_300185 Wed, 08 Feb 2023 08:02:17 +0000 PeterStarck Posted By: maxsmWe hope to insulate the property to a very high standard (somewhere between enerphit and aecb). We are currently leaning towards radiators due to budget and the disruption of digging out for UFH but would like to 'futureproof' our heating by installing a system that would be compatible with ASHP in future.

I assume, as you say "digging out" the floor, that you have solid uninsulated floors. If the floor is not insulated in some way it will be a large impediment to being able to reach Enerphit standards. Do you have sufficient room height to be able to insulate on top of the solid floor.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300191#Comment_300191 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300191#Comment_300191 Wed, 08 Feb 2023 14:59:40 +0000 bogal2
https://www.daikin.eu/en_us/product-group/air-to-air-heat-pumps/multiplus.html]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300192#Comment_300192 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300192#Comment_300192 Wed, 08 Feb 2023 15:49:34 +0000 fostertom Posted By: PeterStarckIf the floor is not insulated in some way it will be a large impediment to being able to reach Enerphit standardsI'm a well known fan of extending EWI down, in a trench, to the bottom of the foundation, forming a 'coffer dam' of insulation around the perimeter of the ground floor slab (incl if it's a void under a suspended timber ground floor), as alternative to insulating the slab itself, the trench being backfilled as a french drain to guarantee that the downstand EWI stays dry, or at least not waterlogged. This makes a fair job of insulating the ground floor without disturbing it (and kitchens etc built on top of it). I don't imagine this could form part of a full PH but I wonder whether it could be good enough for an Enerphit or AECB retrofit.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300194#Comment_300194 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300194#Comment_300194 Wed, 08 Feb 2023 16:32:46 +0000 PeterStarck Posted By: fostertomI'm a well known fan of extending EWI down, in a trench, to the bottom of the foundation, forming a 'coffer dam' of insulation around the perimeter of the ground floor slab (incl if it's a void under a suspended timber ground floor)

If fitting the 'coffer dam' under a suspended timber ground floor, with a deep crawl space, is it fitted from the bottom of the foundations to the underside of the joists. If so, doesn't that prevent effective ventilation of the crawl space?]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300195#Comment_300195 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300195#Comment_300195 Wed, 08 Feb 2023 17:24:22 +0000 fostertom
If the underfloor void is thus kept warmer than outdoors (as intermediate between indoor temp and the subsoil floor of the void, and without uninsulated perimeter cooling), rather than maintained at outdoor temp by through-draught, then there's precious little to cause condensation in the void, so no need for through-draught.

The only half-likely condensation place being the subsoil surface as handy and harmless condensing plate for the whole house.
Any joist ends are maintained warmer than hitherto, and the french drain keeps the whole free of liquid groundwater and/or leakage from RW drain.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300196#Comment_300196 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300196#Comment_300196 Wed, 08 Feb 2023 17:58:39 +0000 PeterStarck Posted By: fostertom"from the bottom of the foundations" up to unite seamless with the wall EWI.

Ahh, I should have read what you said more carefully. I understand now. Thanks.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300199#Comment_300199 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300199#Comment_300199 Wed, 08 Feb 2023 19:31:15 +0000 borpin Posted By: djhASHP run most efficiently when their output is at a lower temperature than a gas boiler. That is perfect for UFH, but often needs larger radiators for an ASHP than for a gas boilerYes and no.

Posted By: jamesingramyou wont require much heating.

Posted By: fostertomyou hardly need a heating system,
I'm really anti this idea. There are far too many instances where you do need heating and often in the living area. It also depends how warm you like your house. My very airtight, close to PH insulation definitely needs heating in central belt of Scotland to maintain a 20.3°C temperature in the living area.

Yes ASHPs run at a lower temperature than boilers, but fitting them directly to UFH is a mistake IMHO. The OEM forum is currently filled with folk paying vast amounts on electricity because the HP is plumbed directly to the UFH and there is insufficient heat demand so the HP simply cycles. Also, you probably want to run the UFH colder than the HP will run at efficiently to prevent overheating. My UFH runs at just over 30°C and there is no way I have a DeltaT of 5°C when it reaches steady state. In the shoulder months, it cycles a bit, running for 30 mins and then off again - but as that is just a circulating pump, it isn't an issue.

I'm sure the right way to use a HP is to have a Thermal Store and then take off the UFH and use a blending manifold on the UFH. You can use that same TS to take the rads off as well, just at a higher temperature. A TS with a baffle/stratification so the top can be heated instead of the whole tank is even better as you then only need to heat to a higher temp for a while when you need DHW.

The important aspects or the renovation are airtightness and insulation. With airtightness there is then the need for a MVHR system (which again reduces the heat load).

Get a proper heat demand survey done to size the rads and UFH. If you run it cooler, you cannot have too many UFH pipes.

You can fit the tank to the existing boiler (turning it down to maximise efficiency) and when that turns up it's toes, replace it with a HP.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300200#Comment_300200 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300200#Comment_300200 Wed, 08 Feb 2023 20:04:46 +0000 fostertom Do all HPs cycle, like an old fashioned boiler? Recipe for waste. Why don't they modulate?]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300202#Comment_300202 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300202#Comment_300202 Thu, 09 Feb 2023 18:45:13 +0000 djh Posted By: borpin
Posted By: jamesingramyou wont require much heating.

Posted By: fostertomyou hardly need a heating system,
I'm really anti this idea. There are far too many instances where you do need heating and often in the living area. It also depends how warm you like your house. My very airtight, close to PH insulation definitely needs heating in central belt of Scotland to maintain a 20.3°C temperature in the living area.Our house actually does have PH insulation and airtightness and yes it needs some heating overnight but then maintains or increases its temperature through the day as long as there is some sun. If there isn't going to be much sun, I put more heat in the night before. Where you live doesn't make any difference, since PH is performance based and the insulation needs to match the conditions. The same goes for EnerPHit.* Temperatures within the house can vary a degree or two from the north-facing to the south-facing rooms but nothing that bothers us.

Yes ASHPs run at a lower temperature than boilers, but fitting them directly to UFH is a mistake IMHO.
I didn't suggest connecting the HP directly to the UFH, so I agree with you.

As I said at the beginning, given the OP's state of knowledge they should be taking professional advice about the design of a PH/EnerPHit-level retrofit and also about installing an ASHP-based heating system.

Specifically, for an EnerPHit refit, you will typically need (25*floor area) kWh of space heating per year. See https://passipedia.org/_media/picopen/9f_160815_phi_building_criteria_en.pdf for more explanation.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300325#Comment_300325 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300325#Comment_300325 Fri, 17 Feb 2023 09:21:06 +0000 maxsm heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300326#Comment_300326 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300326#Comment_300326 Fri, 17 Feb 2023 11:11:49 +0000 WillInAberdeen
The coffer dam idea has been discussed a few times, it would certainly help a bit, but it won't get you those two things.

An Enerphit house of say 100m² needs 2500kWh/a of external heating. Using a fan heater would cost around £500 of electricity each year (depending what happens to electricity prices) and would need a fan heater around 1kW capacity.

It's hard to think of any heatpump or gas boiler system which could end up cheaper than that over their lifetime, they basically don't make them small enough, and they will cost multiple £k to install with the radiators or UFH.

Possibly a small air conditioner (a-a heatpump) could be worthwhile? Or a few m² of electric UFH mats.

If you went for a less demanding standard of insulation, then a heatpump would become worthwhile. Because of its efficiency, it might actually use only the same electricity as the example of a fan heater, but you'd need to do the sums whether to spend the capital on insulation or on a heatpump system.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300327#Comment_300327 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300327#Comment_300327 Fri, 17 Feb 2023 12:11:13 +0000 bhommels 1- direct electric. Cheap & easy to install. It makes me vulnerable to price swings and inflation, which I don't like. It remains to be seen if the grid intensity in winter is substantially lower than my very efficient boiler anytime soon.
2- ASHP: High-ish installation costs. Efficiency is a problem, because I only need heat when the average outside temp drops below 8-10C. At that point, the COP will drop to 2.5 or lower, and it will be spending lots of energy defrosting itself (which is not accounted for in the COP!!)
3- GSHP is the ideal solution in the long run but very expensive as a turn-key installation. This could be mitigated by DIY'ing the borehole or slinky laying. This is not impossible since the annual heat extraction is low: 60m slinky or 40m combined borehole depth would be sufficient. The smallest GSHP is only just small enough.
The boiler is still young and will probably keep going for a very long time, so there is time to decide.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300330#Comment_300330 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300330#Comment_300330 Fri, 17 Feb 2023 21:21:51 +0000 GarethC 2. I'm fairly sure a well specified ASHP gets significantly better than that at those temps.
3. Surely the massive embedded carbon involved in installing the thing makes it not worthwhile from an environmental point of view?
What about multi split Aircon?]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300332#Comment_300332 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300332#Comment_300332 Sat, 18 Feb 2023 12:29:19 +0000 WillInAberdeen
That doesn't include embodied carbon though.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300346#Comment_300346 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300346#Comment_300346 Sat, 18 Feb 2023 22:27:42 +0000 bhommels Posted By: GarethC
2. I'm fairly sure a well specified ASHP gets significantly better than that at those temps.
Even owners of well specified, well installed ASHPs are disappointed in their performance when it gets close to freezing due to the defrost cycles. A large fraction of my heat requirement is at those temperatures. Paying a lot of money for a non-ideal system does not look very attractive to me.
3. Surely the massive embedded carbon involved in installing the thing makes it not worthwhile from an environmental point of view?

An ASHP is a more complex device than a GSHP and therefore probably has a higher embedded CO2 footprint. Only direct electric is clearly better in this respect. GSHPs generally are said to have longer lifespans, too.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300349#Comment_300349 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300349#Comment_300349 Sun, 19 Feb 2023 12:49:47 +0000 borpin Posted By: bhommelsEven owners of well specified, well installed ASHPs are disappointed in their performance when it gets close to freezing due to the defrost cycles. A large fraction of my heat requirement is at those temperatures.The answer is to possibly use Glycol rather than water so no need for defrost cycles.

Equally, from discussions on OEM, it does seem that some of this disappointment may be due to badly designed and tuned systems.

https://heatpumpmonitor.org is starting to gather a good cross section of data.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300350#Comment_300350 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300350#Comment_300350 Sun, 19 Feb 2023 13:46:05 +0000 bhommels Posted By: borpinThe answer is to possibly use Glycol rather than water so no need for defrost cycles.
As far as I have been told, the problem is icing up of the evaporator ('radiator'). Humid air is sucked in at just above 0C. It is then blown past the evaporator, which sits well below 0C. Ice forms on the outside of the evaporator, blocking up the channels. The ASHP has to 'go in reverse gear' to heat up the evaporator, using an in-built electric heating element, to get rid of the ice, and go back to normal operation until it has detected it has iced up again. This is a fundamental aspect of ASHP operation and is independent of the refrigerant, sizing of the ASHP, or even quality of the installation (although this can make it worse).
For not so well insulated homes, the bulk of the heat is delivered when it is below 15 C but not close to freezing yet. At those temperatures it is not so much of a problem. Well insulated homes will require heat at lower outdoor temperatures, and then this issue becomes more important.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300353#Comment_300353 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300353#Comment_300353 Sun, 19 Feb 2023 15:27:49 +0000 GarethC
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/225825/analysis_data_second_phase_est_heat_pump_field_trials.pdf

Re difference between ASHP and GSHP, perhaps I characterised incorrectly. When I've seen an ASHP installed the outside compressor took a couple of guys a few hours. When I've seen GSHPs installed the trench or borehole involved several days of diesel powered machinery. It's that aspect that struck me as carbon intensive. Not sure what the net impact is.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300354#Comment_300354 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300354#Comment_300354 Sun, 19 Feb 2023 15:31:19 +0000 djh Posted By: bhommelsAn ASHP is a more complex device than a GSHP and therefore probably has a higher embedded CO2 footprint.Only if you're considering just the heat pump box I suspect. Presumably you're referring to the evaporator and associated fans etc? But if you include the GSHP's equivalent long slinky pipe or boreholes then I suspect it may come out worse. There's a lot of embodied carbon in an HDPE pipe.

edit: crossed with Gareth. Yes, the installation work also has carbon emissions :shamed:]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300356#Comment_300356 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300356#Comment_300356 Sun, 19 Feb 2023 17:26:36 +0000 WillInAberdeen
The downside is that heating is interrupted for a short period during the defrost cycle, which householders notice and complain about. So the manufacturers try and stretch out as long as possible between defrost cycles, by which time the ice gets quite thick, impeding the heat transfer and CoP.

The heatpumpmonitor.org that Borpin mentioned shows that poorly insulated pre-1900 homes are getting CoPs better than passivhauses, because it's mainly the indoor radiator/ufh temperature that determines the CoP, not the outdoor temperature or the insulation quality. Instead, those factors determine the total kW or kWh required.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300361#Comment_300361 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300361#Comment_300361 Mon, 20 Feb 2023 11:35:59 +0000 djh Posted By: WillInAberdeenThe heatpumpmonitor.org that Borpin mentioned shows that poorly insulated pre-1900 homes are getting CoPs better than passivhauses, because it's mainly the indoor radiator/ufh temperature that determines the CoP, not the outdoor temperature or the insulation quality. Instead, those factors determine the total kW or kWh required.I just had a quick look at the site and don't understand how you reach that conclusion? There's only one entry that claims to be a passivhaus and it uses a GSHP whereas all the others use ASHP so I'm not sure what conclusions can be drawn? And some heat DHW while others don't etc etc.]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300362#Comment_300362 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300362#Comment_300362 Mon, 20 Feb 2023 11:38:09 +0000 bhommels
@WiA: the COP is a convolution of many things and I am not sure how to interpret your statement. Are you saying that leaky pre-1900 homes run lower radiator/ufh temperatures than PHs? Or are you trying to support my initial statement that PHs need a relatively large fraction of their total heat requirement at lower outdoor T so that icing up is a problem?]]> heating options for eco retrofit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300365#Comment_300365 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17733&Focus=300365#Comment_300365 Mon, 20 Feb 2023 16:27:37 +0000 fostertom