Energy infrastructure

Adding rads and a boiler is drastically different compared to making a house well insulated and airtight enough to facilitate a heat pump.

Orders of magnitude in the difference.

Stuff like Cost Benefit Analysis etc. appears to be alien concepts to those who control energy policies in this country atm

Insulation is a separate issue.

Heat pumps aren't special. A poorly insulated home will more difficult and will cost more to heat regardless of the source of the heat - gas, oil, coal or electric heat pump. Whatever the source of heat for your home, insulating as much as possible makes sense.

I think there is a widely held impression that heat pumps can only work in highly insulated homes due to their earlier association with modern well insulated new builds especially "passive home" type levels of insulation.

But this isn't the case - all heating systems just add heat to the inside of your home. If your gas boiler is putting 200 kWh of heat into your house every day (say a 35kW boiler running for 6 hours a day), then you need a heat pump that can do the same. Since heat pumps run constantly, the calculation is a bit different - in this case a 10kW output heat pump running constantly will put 240kWh of heat into the house every day.

To heat a drafty poorly insulated house using a heat pump you'll need a unit with larger capacity (which will cost more to buy and to run) but that's the same with gas or burning coal or any other home heating technology. Burning gas doesn't magically change this - my parents' house is old and difficult/impossible to bring up to modern heating standards and their gas boiler struggles to keep the house at a comfortable temperature. They would have the same problem with a heat pump system.

The problem with heat pumps isn't technological - it's financial. The running costs - fuel and maintenance - to generate the same amount of daily heat are only a bit less than using a gas boiler for now - given that until last year gas was "cheap". But the capital costs are much higher so it's difficult to financially justify the higher initial cost of the unit versus a gas boiler even considering the whole lifecycle costs. This is especially true for "legacy" homes where the existing pipework and radiators can be considered a sunk cost and so are seen as effectively "free" when coupled with a boiler.

But this is just a legacy issue - burning coal seems a "cheaper" way to heat a house that currently only has open fireplaces considering the capital cost of installing central heating and radiators, etc.

But gas and oil will inevitably get more expensive - whether because of global forces or due to introducing carbon taxes. While the cost of heat pumps will fall - they are a mass produced item and so the more sales, the more production, the cheaper they'll get. In many western countries, heat pump/underfloor is now the most common form of heating in new builds. We've seen the same thing play out with EVs, grid solar PV/wind, battery storage, etc. which were all initially more expensive for many use cases than the legacy alternative but then the economics flip. I'm confident heat pumps are on the same path just that it'll be a bit slower.

If you install a heat pump in a poorly insulated home, it will struggle to heat the home. The heat loss from the home is too great for a heat pump to compensate, since max power output of a heat pump is nowhere close to that of gas/oil or solid fuel.

Its not just a case of matching heat output from your gas boiler with heat pump instead - heat pumps operate at lower temperatures over longer periods of time, whereas combustibles tend to operate for shorter periods, but hotter. Often in houses the house gets warm quite fast after heating has been on, then cools afterwards as heat is lost from the house. To try and match this energy input using a heat pump over 24hr period would end up with consistently too cold house.

The transition from gas/oil will not be as simple as "slap a heat pump there instead of boiler" - it will require massive retrofits to more than half of housing stock in entire country. I agree the problem is not technological as such, its financial - does the state have the money to do all this? Do we have the labour available to do all this? I would say no.

You make some reasonable points with some I disagree with.

First, can we drop the strawman stuff? It's easy to dismiss my argument by summarizing it as "its as simple as slapping a heat pump instead of a boiler". I've absolutely never claimed it would be as simple as swapping a boiler for a heat pump. I've said repeatedly the transition will be non-trivial and that it will happen slowly - decades - and that at the moment the financials make it difficult to justify a retro-fit even if it works for new build. I've acknowledged all this.

You have a point with your second paragraph - the patterns of heating are different - which is an added inefficiency of using a heat pump IF you can live with cold and warm periods during the day for example if the house is empty say from 9 til 6 or you don't mind temperature drop overnight, gas gains efficiency by allowing you to let the temperature drop during that period. Gas is more responsive, no argument there. Is this a deal breaker for the technology? I don't honestly think so. Where I currently live has underfloor heating connected to a large district heating (gas) boiler and is similarly unresponsive - you get used to it quickly.

But I don't agree with your first point. A home constantly leaks a certain amount of heat (proportional to the temperature differential with the outside) and to maintain an inside temperature your heating appliance has to have enough heat generating capacity to compensate for this leakage.

The capacity issue is the same for any home heating technology - an undersized gas boiler will struggle as will an undersized heat pump - e.g. my parent's old drafty empty nest house basically cannot be upgraded to modern BER standards without a complete re-build and cannot be heated fully by their 35KW gas boiler - so they turn off the radiators in some of the rooms so that the others are comfortable - or also fire up their wood stove in the sitting room. Capacity is not an argument against heat pumps - you can get huge heat pumps if you're willing to pay just like you can get huge boilers, or run multiple units, or burn stuff in multiple stoves, etc.

Your heat pump would have a very short life & be insanely expensive if you fit it in a poorly insulated house, even if it were a "huge" heat pump. While heat pumps are intended to be "on" 24/7, they dont actually do anything for most of that time. The intention is that they go when the temperature drops, and then switch off. So overall power drain is quite low.

Were your heat pump to be actually going 24/7 you would be wasting eyewatering amounts of electricity, and the lifespan of your pump would be vastly degraded. Totally uneconomical to fit them in houses that are not very well insulated. The idea that you just get a bigger capacity heatpump to compensate for greater heat loss in the home is just incorrect. Totally wrong.

You remind me of those chancers in the Irish energy market that claim to provide "100%" green energy, yet are putting up their prices due to "gas and oil inflation" ie. utterly clueless when it comes to pricing grid energy or any notion of concepts like fuel mix, the loss of conventional power plant efficiency due to accommodating wind power etc.