30 January, 2024
Blog by Solar Energy UK member Stuart Elmes founder and Chief Executive of Viridian Solar accessed via The Solar Blogger
On December 22nd 2023 Scottish Government published an update to the Building Standards Technical Handbook which will apply to new building sites where a building warrant is applied for after April 1st 2024.
The update to the handbook was made to implement the New Build Heat Standard which bans the use of ‘Direct Emission Heating Systems’ – gas or oil boilers in plain English – from newly built homes and some conversions of existing properties. Instead, developers must now choose from a heat pump, direct electric heating (storage heaters or infrared panels) and connecting to a heat network (if available).
In 2015 Scottish Government introduced solar PV into its building regulations – well ahead of England which was to take until 2021 to catch up. This has resulted in a thriving solar industry in Scotland, installing far more solar to domestic properties per head of population than the rest of the UK (see my earlier blog: How Progressive Building Regulations Made Scotland a Solar Powerhouse).
Unfortunately, Scottish Government has ignored repeated warnings from Solar Energy Scotland that the introduction of the New Build Heat Standard without an accompanying adjustment to the Building Standards could threaten the success story of Scottish solar.
Working in Silos
To understand how the new regulations could harm the solar industry in Scotland we need a little background on how the building regulations work. The regulations are not prescriptive, they aim to give the designer freedom to choose how to build the house – instead of defining each and every building element, the set a level of energy performance that the house must achieve.
A developer must show that the house they are planning to build uses no more energy than a home of the same size and shape built according to a defined specification called the Notional House Specification. (For more details on how this works see my earlier post on Energy in Building Regulations). Over time the regulations have made new homes more and more energy efficient by changing the Notional House Specification to have a better and better energy performance.
The last major review of Building Regulations in Scotland (in 2021) introduced two specifications for the notional house – one for homes with heating by a gas boiler, the second for a house with a heat pump.
In order to ‘nudge’ developers towards using more heat pumps and away from polluting gas boilers the specification with the heat pump included a number of cost-saving relaxations in other areas – notably the omission of solar PV panels which were included in the gas heating specification.
Although it might have been an admirable intention to nudge developers towards heat pumps (it didn’t work by the way – gas boiler and solar remained the preferred design choice), it was clear that if the New Build Heat Standard was to come in without changing the notional house specification at the same time, then the only legal specification becomes the one with the heat pump, and solar would be dropped from the notional house in Scotland for the first time since 2015.
Unfortunately we were talking to two different sets of officials from Scottish Government – one working on the building regulations and the other working on the New Build Heat Standard. Our concerns were ignored. The latest regulations have enacted the boiler ban and left the Notional House Specification unchanged.
The Impact on Solar for New Homes in Scotland
This unwelcome development is not necessarily all bad news for solar.
First of all, housebuilders may choose to combine solar PV with a heat pump in their designs, not least as a way of keeping a lid on energy bills for their customers. This change to the building regulations is probably the first ever update to result in higher bills for consumers. Electricity costs far more than gas does – and the enhanced efficiency of heat pumps does not make up for the difference. Developers can offset this rise in bills by keeping solar in their design.
Secondly, solar has become a common sight in new developments across Scotland and customers have come to expect it on new homes and increasingly see energy efficiency as a reason to buy new rather than in the general housing market.
Third the gas boiler plus PV specification still applies to homes with direct electric heating. Developers may explore this option, adding better insulation to the point where space heating demand is reduced to an absolute minimum – especially for smaller properties.
Finally, since new regulations only come into force from the point of applying for a building warrant it is likely to take a year or so before sites begin construction under the new regulations, and 2-3 years before the majority new homes being built are to the new standard. What could change in this time? Here are some thoughts:
- Alex Rowsley MSP proposed that Scotland move to a Passivhaus basis for building regulations, and in December 2022 Scottish Government announced that it would legislate for this by December 2024. We may have a new version of the regulations in less than 12 months time.
- The European Commission announced a strengthened Energy Performance of Buildings Directive in December 2023 in which “Installing solar energy installations will become the norm for new buildings”. The current Scottish Government is very keen on aligning its regulations with the EU with its goal of quitting one union and re-joining another.
- A new Future Homes Standard for England is embracing smart energy, time of use electricity tariffs, energy storage and solar generation with a new half-hourly calculation method, and is beginning to make the Scottish approach look rather passé. A strong Future Homes standard specification with heat pump and solar will encourage the Scottish Government to surpass it.
- Who knows how far battery storage, solar and smart energy technology will developed by this time? If we were to go back four years, battery storage was only for dedicated enthusiasts and off-grid applications – now it’s included with around half of all retrofit solar installations. The performance and cost of solar and energy storage continues to make the technology more widely applicable and attractive. More recent innovations such as time of use tariffs and electric vehicle to grid charging will only add to the advantages of having solar on your home
Whether the omission of solar PV from the notional house specification in Scottish building regulations slows the adoption of solar PV in Scotland remains to be seen. What is clear is that, at worst, it will only temporarily slow its rise.