EPC upgrades account for a third of renovation costs

One of the reasons why it costs so much is that new-builds are zero rated for VAT but refurbishments aren't.

There's nothing environmentally sustainable about that policy.

There's something new in the press about heat pumps here which is relevant to the cost of retro-fitting energy performance improvement measures:

https://www.telegraph.co.uk/opinion/2023/02/28/letters-heat-pump-drive-part-energy-plan-puts-consumers-last/

These letters have one comment from someone who says this about air source heat pumps:

"SIR – The cost of installing a heat pump (Letters, February 25) is often quoted as between £7,000 and £13,000. This may be true for homes built recently, but it was not my experience. I live in a four-bedroom house built in the 1960s, with cavity wall insulation and loft insulation. I was keen to install an air source heat pump and received three quotations – all over £20,000. The reason given was that larger radiators and pipework were required. As well as costing more, this would have involved a huge upheaval, with carpets and flooring tiles being lifted. Since the radiators would have been working at 40C, it would have been necessary to use electricity to heat water for baths, for instance. The operating costs were still expected to exceed £2,000 a year. Needless to say, an oil boiler is now being fitted instead."

And there's another letter that says this about ground source heat pumps:

"SIR – My Swedish ground source heat pump is served by two 330 ft-deep boreholes, and delivers heat consistently and cheaply.

It has been running for three years without any problems, and the servicing costs are about £150 per annum. More importantly, when combined with a solar array and a well-insulated building, the results are staggering. My electricity bill for 2022 was a shade over £100. A temperature of 21C is maintained throughout the house. The fact that a ground source unit delivers four kilowatts of heat for each one consumed cannot be ignored."

I cannot find consistent advice on heat pumps anywhere. One of those surveyors that work for a company selling insulation told me last year that ground source heat pumps are expensive to install and maintain. I have also seen information online to say that their performance declines each year and that their lifespan might only be ten years. I have struggled to find reliable information anywhere.

Does anyone know what the truth is about ground-source heat pumps? Anyone know how they perform in Sweden, how their performance changes over time and how long they are expected to last?

Also does anyone know what the tax treatment of this is? Are they zero-rated for VAT? Are they zero rated for VAT only for new-build? Is the expense of retro-fitting a 'renewable' heating source definitely deductible against revenue expenses?

I can't see anything sustainable about bulldozing old houses to create new ones and I suspect that the solution lies somewhere in reliable information on newer technologies and modifications to our tax system.