Heat pump mythbusters commentary - part 3: Can heat pumps be installed in older properties?

Article 3: can heat pumps be installed in older properties?

Article summary

1. There is a widely held belief that heat pumps cannot adequately heat older homes and as such are only suitable for new-build properties.

2. However, several studies have shown that heat pumps can be successfully installed in all types of property.

3. There are space implications of installing heat pumps, both internally and externally.

4. Blocks of flats are likely to be better suited to shared larger scale heat pumps (rather than each flat having its own heat pump) or district heat networks fed from waste heat or centralised heat pumps.

Read the full article here.

Additional commentary 

1. It needs to be reiterated that existing leaky properties lose heat, whatever the source of that heat is. Better that this heat is generated efficiently and cleanly by heat pumps with zero local air pollution, than through fossil fuel boilers, which not only emit carbon dioxide but also nitrous oxides, sulphur oxides and other particulate matters.

2. The property in which I have recently installed a heat pump is mid-terraced, double-glazed (generally glazing >20 years old) with solid walls and no wall insulation. There are two post-millennium small extensions which are reasonably well insulated. As part of the work, the only real upgrade made to the existing heating system was increasing the size of the radiators. In our first winter living with the heat pump our house has been more comfortable than any previous winter and we have never lacked for hot water.

3. Heat pumps must be suitable for use in existing properties as the majority of buildings which will exist in 2050 already exist today. Ignoring the carbon arguments, we simply can’t knock down these properties and start again, we barely manage to build 200,000 properties per year in England as it is.

4. In 2023 there were 37,000 heat pump installations and with approximately 30 million domestic properties in the UK it would take over 800 years for heat pumps to be installed in all of them. Even at the (current) government’s target rate of 600,000 heat pump installations per year by 2028 – ambitious relative to the current trajectory – it would take over 50 years, which is simply not fast enough. Mechanisms such as the Boiler Upgrade Scheme are resulting in a small increase in uptake, however not nearly enough is being done to increase the number of installers, encourage home-owners or rebalance the skewed prices of gas and electricity.

5. Putting aside older properties for one moment, it is staggering that our current Building Regulations still permit gas boilers to be installed in brand new dwellings. These new dwellings will become the older properties of the future! It is much more straightforward and cheaper for heat pumps to be designed in and installed as part of a new build than retrofitted. Hopefully the Future Homes Standard, due for introduction in 2025, should address this.

6. Most properties in the UK have heating and hot water provided by a “combi” boiler, without a hot water tank. However, combi boilers have only really been widespread in the UK since the 1980s, and before this, houses relied on storage tanks for providing hot water. So finding space for a tank is not a new concept!

7. Not all heat pumps take up the same amount of space, for example Ground Source Heat Pumps do not need an external unit. If outside space is at a premium and Ground Source is unsuitable then Exhaust Air Heat Pumps can be located internally and ducted to outside. This type of heat pump also provides efficient mechanical ventilation with heat recovery. New solutions are also being developed which might be able to be incorporated into houses more easily, for example through-roof versions. In short, there will be a suitable heat pump for all properties.

8. Permitted development rights allow heat pumps to be installed in England and Scotland without requiring planning permission if the heat pump is located >1m* from a neighbouring property. However, this arbitrary distance stifles installations in many property types, such as in terraced houses which make up over a quarter of the UK’s housing stock and are generally a good fit for heat pumps due to their relatively low heat loss in comparison to detached houses. In England, this distance rule was in the process of being scrapped, allowing heat pumps to be installed closer to neighbouring properties, however it is unclear how the general election will impact this change.

* This is >3m in Wales and a mind-boggling >30m in Northern Ireland!