Sorry by 25% I meant his bill is 25% of what is was ie a 75% saving, which is quite an incentive, although his motivation is environmental.
Your are right that energy is too cheap, in historical terms its probably cheaper than its ever been. I suspect carbon taxes will rise across Europe that will bring the gas price up to that of electricity. The issue for governments is fuel poverty, this has to done carefully as there will be people left behind, another round of 100% grands for insulating old homes would probably help, uptake of past schemes was always low when energy was cheap.
My guess is renewable electric costs will fall and gas taxes will raise to incentivise consumers to switch away from gas.
In terms of water heating, most heat pumps will provide hot water at 55c, this is hot enough for a bath or shower, but it requires a bigger storage tank as gas C/H water is heated to 65c and then diluted with cold, so you need a bigger reservoir, I presume legionella protection is a bit different, but don't know.
I expect heat pumps will fall in price to become affordable as mass production takes hold, but subsidies would probably be needed to replace the entire national stock of gas boilers.
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