@stevebrockie3 Hi Steve and welcome. 

We were advised by Peter Wilkinson from Dales Contracts (who's built houses to Passivhaus standard and who installed our underfloor and loft insulation) that ideally we should look at super insulation (preferably external wall) and reducing drafts before getting an ASHP. We had rotten, failing wooden double glazing dating back to the 1980s where you could see the curtains moving in a gentle breeze. 

We didn't fully take all Peter's advice but in our 135m sq 3 bed brick built 1950s bungalow in North Yorkshire we did:

• Cavity wall insulation with carbon beads (cost £1300 - didn't get the voucher for this bit) - 2021
• 250cm loft insulation (2013)
• As much under floor insulation as possible, with some fancy things like boron bits in the joists that Peter said were a good idea (got this done in 2013)
• Replacement U-pvc double glazing with Planitherm clever coating (cool when hot, hot when cool - it's worked in the very hot weather this summer) 2021 
• ASHP - LG Therma V HM121M U33 (RHI payments cover most of £11K) (2020)
• Solar PV 4kw (I think about £1800 from memory) (2020)
• Solar Thermal (Green voucher for 2/3 of £5500 cost) (2021)

Until we got the new windows, the electricity demand with the ASHP was costing more than our previous gas bill. The cavity wall insulation made our house too hot for the first time ever - as a woman of a certain age, this was not good, but my husband is delighted. We replaced our 15 tog duvet with a 5 tog one and I've conceded that a room temperature 20 degrees is bearable (rather than my preferred 18 or 19 degrees). 

We signed up to Octopus Agile but found that we were using too much power later on in the day when it was very expensive so we've gone back to the standard tariff. We are on the export tariff too, which although not that lucrative, has been great to get that few quid extra off the electricity bill. 

My fear with the national roll out of ASHPs as the answer to decarbonising is that Peter Wilkinson will be right with his words of warning, "You'll just be installing a giant electric fan heater unless you do the insulation and draft control". 

Eventually we plan to get a bigger solar PV array to fill the roof, and perhaps get a heat battery (see www.sunamp.com). In fact, I wish I'd explored heat batteries + ASHP before getting ours installed, and we could perhaps have avoided having such a big water cylinder and buffer tank. We're also looking at how best to do electric cars and charging but when I explored the cost of battery installation, even as part of an experiment/trial where the installation cost was waived, it was still too costly after everything we'd already done. 

I would definitely recommend doing the insulation - loft, floor and cavity wall - and if you can afford external and/or internal wall. Peter W did say that from a cost point of view, getting a new efficient gas boiler plus the insulation would make more sense. I would also prioritise your drafty windows before you install your ASHP.

We had our EPC re-done to get the RHI payments and we're now 73 C up from an E rating.

However, my aim was to decarbonise and put my money where my mouth is, with the help of the GHG and RHI payments. The upfront cost was big but what else can individuals do about climate change? 

Hope all that helps!

Zoe

@pumpo-sorcerer I think you might have 250mm of loft insulation? 2.5m is very very well insulated!!

@pumpo-sorcerer thanks Zoe for sharing your experience.

That is my concern, if the heat loss is there now, changing your heating source isn't going to magically fix that, so you are just swapping one expensive heat source for another.

I hadn't appreciated that cavity wall insulation was so affordable.  I did look at external wall insulation but it was too expensive for us if we want to do the ASHP and windows.  But Windows, ASHP and CWI we could probably stretch to - we'd always planned to upgrade the loft insulation and I believe we can actually get underfloor insulation upgraded for free in Scotland for having children under the age of 5.  So maybe all that combined would make ASHP effective.

Our EPC is currently E and we are told it will bring it up to C, so much like your experience.

Really insightful to see the measures you've put in place.  So would you say now that your electricity bills are manageable?  And by the sounds of it the house has no problems reaching desired temp.

@batalto 🤣 🤣 Well spotted!

@stevebrockie3 Combined gas and electricity bills were astronomical when we first moved in in 2013, around £250-300/month and it was still cold. Now around £135/month but I think that will be an overestimate. We've also trained the kids to have showers now too, unless it's a sunny day when they can have a 'free' bath! 

@batalto, I wish we had 2.5m of insulation - that would be awesome.

Welcome to the forums @stevebrockie3

A year ago, I would have been a lot more supportive in proceeding with the limited insulation and your heat loss. That opinion changed for us when we hit -6C this Feb, and I realised how much more support a heat pump needs to be effective (speaking our home's perspective).

Heat loss is a big deal and if you're losing heat at the moment with LPG and your heating doesn't keep pace in keeping your house warm, your heat pump won't and your house will feel a lot colder. We are relatively well insulated, but definitely leak heat, and a lot of it stemmed from the heat emitters. When we increased to K3s in the rooms that were struggling that did wonders. 

Ask your installers about the heat emitter guide and what needs to be upgraded/upsized to maintain rooms at temperature at lower flow rates.

The recommended upsized heat pump is a good idea because you want that room for it do more if it has to. What brand(s) have they recommended?

@editor thanks for your response and advice.

They’re suggesting a Grant Aerona3 R32 17Kw. On your advice I’ve gone back and asked what radiators they’re suggesting to replace downstairs - we have K3s upstairs which I assume is why they haven’t suggested replacing the upstairs radiators.

Do you think with improved cavity wall insulation, additional loft insulation and new windows would improve its chances?

it’s been a stress, I’ve got a 1 year old and another due at Christmas and I just want to make the home as comfortable as it can be, it’s hard knowing what is the right thing to do.

@stevebrockie3 do the insulation first then you'll need a smaller ASHP. Our house is 260m2 and we only have a 12kw unit. Plus it'll allow you to use less heating and turn the current system down. Last winter I turned ours to 55° for the whole winter and there were no issues. It was the best way to test out the impact of switching to an ASHP

@batalto makes sense right enough, we'll deffo be doing the loft and the walls, we're on a waiting list for the underfloor as its a council run initiative but we've got 50mm there for now at least.  Hopefully that and new windows will significantly reduce the heat loss and we'll get the benefit of the ASHP

Hi stevebrockie3,

Welcome to the forum.

As I have been repeatedly saying, improved insulation and draft proofing should always be the starting point. Reducing the heat loss means you need to use less energy in the first place.

Before going to the expense of replacing double glazed units, I would suggest that you first check for damaged or hardened seals, which may be the source of drafts. New seals can be obtained and fitted at quite reasonable cost, thereby allowing the savings to be used for other types of insulation improvements.

The only problem I can see with getting an oversized ASHP, is that the running costs could be slightly higher, since it will have a larger electric motor to drive the larger compressor, and hence will consume more electrical energy.