New Building Regulations for Scotland

In June 2022 the Scottish Government published its consultation response on changes to further tighten the Building Regulations for energy efficiency.  New developments in Scotland seeking a Building Warrant after 1 December 2022, will need to meet the new regulations.

Although most respondents to the consultation were in support of a higher performance target (delivering a 57% reduction in CO2 emissions), the government instead opted for the lower performance target which is expected to reduce the CO2 emissions of new homes in Scotland by 32%.

The central element of the building regulations for energy is the so-called 'Notional House Specification' which defines the target that a developer must meet. (For a full explanation of how the Notional House Specification works see this earlier blog).

The 2022 Building Regulations in Scotland gives three Notional House Specifications - one for homes heated with a heat pump, another for homes heated by a heat network and a third based on mains gas  for homes using any other heating systems.

The table below contrasts key elements of the new Notional House Specification with those in the previous version of Scottish Building Regulations and also with the new regulations that came into force in England this year.

As can be seen, the new Scottish Building regulations require a significant improvement in U-values (insulation) and airtightness compared to the current (2015) regulations.  They also come in slightly better than the latest regulations for England (it would have been a major surprise if they didn't!)

Of interest to solar industry participants will be the increase of PV provision in the gas heated notional house compared to the 2015 regulations.  

In 2015 Scotland became the first of the nations to add solar PV to the notional house - the amount asked for was the dwelling total floor area in m2 x 0.01kWp, which corresponds to 20Wp of solar per 1m2 of ground floor area (for a two storey building of equal ground and first floor areas).  The new requirement is for 0.4 x ground floor area in m2 / 6.5 -  which works out to be 62Wp of solar per 1m2 of ground floor area - around 3 times more solar per house.

Other Changes

Scottish Goverment also changed the way the benefits from solar are taken into account in the calculation.  The energy and carbon benefit of on-site generation is capped at the level assessed as being used on site (excluding the energy exported the grid).  This change is likely to incentivise the use of technologies to store excess solar energy for later use - for example battery storage or energy diverters that heat hot water with excess solar energy.

Good News for Solar?

The new regulations look like great news for solar in Scotland.  The Building Regulations are 'solution neutral' allowing developers to choose a combination of heating system, insulation and on-site generation that equals or exceeds the performance of the Notional House Specification.  Since both developers and house buyers prefer gas boilers to heat pumps, this regulation change is likely to increase the amount of solar installed on new homes in Scotland because of the three-fold increase in panel power in the specification.

However, the cloud on the horizon for the solar industry is another piece of legislation - the New Build Heating Standard, which will remove the gas boiler option for housebuilders by banning their use in new homes.  

Under these Building Regulations, once a housebuilder is forced to use heat pumps, the requirement for solar drops away because the Notional House Specification for heat pump heated homes does not include it.

Solar PV and heat pumps are a great match, with solar offsetting higher running costs of heat pumps - why would Scottish Government have no solar on the heat pump specification?  It all boils down to the cost for the developer - the regulations have been set up to encourage housebuilders to consider heat pumps before the 2024 regulations, and the notional house has been set up to try to level the playing field for build costs - leaving waste water heat recovery and solar off the heat pump specification.

No heed has been paid to the increased running costs the home owner will suffer in a heat pump heated home compared to a home with a gas boiler and solar PV.

Once there is a regulatory requirement in place to use a heat pump, then then the incentive to try to lower the cost of a heat pump installation versus gas plus solar falls away.  Scottish Government should commit to review the building regulations at the same time as bringing in its New Build Heat Standard to require solar PV on heat pump heated homes too.  This way it will ensure a just energy transition and reduce the risk of a consumer rejection of heat pumps.