The Scottish Government published an update to its Building Standards Technical Handbook on 22 December 2023, implementing the New Build Heat Standard1. The update applies to new building sites where a building warrant is applied for after 1 April 20241. It bans the use of "Direct Emission Heating Systems", described as gas or oil boilers in plain English, from newly built homes and some conversions of existing properties1. Developers must now choose from a heat pump, direct electric heating such as storage heaters or infrared panels, and connecting to a heat network if available1.
The New Build Heat Standard was enacted without any accompanying change to the Notional House Specification, the defined specification a developer must show a planned home does not exceed in energy use1. Scotland's last major review of building regulations, in 2021, introduced two specifications for the notional house: one for homes heated by a gas boiler, and one for a house with a heat pump1. The heat pump specification included cost-saving relaxations elsewhere, notably the omission of solar PV panels that were included in the gas heating specification1. With the boiler ban in force, 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 20151. The gas boiler plus PV specification still applies to homes with direct electric heating1.
Solar Energy UK published the assessment on 30 January 2024, written by member Stuart Elmes, founder and chief executive of Viridian Solar1. It states that the Scottish Government ignored repeated warnings from Solar Energy Scotland that introducing the New Build Heat Standard without adjusting the Building Standards could threaten Scottish solar1.
"The latest regulations have enacted the boiler ban and left the Notional House Specification unchanged."
Solar PV was introduced into Scottish building regulations in 2015, ahead of England, which followed in 20211. Solar Energy UK states this produced a thriving solar industry in Scotland, installing far more solar to domestic properties per head of population than the rest of the UK1. The assessment notes that housebuilders may still choose to combine solar PV with a heat pump, not least to keep energy bills down for customers, and that solar has become a common sight on new developments in Scotland1.
Why it matters for households
The standard changes what heating a newly built Scottish home can have, and therefore what a buyer of a new home will be offered. Gas and oil boilers are no longer an option in new builds covered by the standard, leaving a heat pump, direct electric heating or a heat network connection1. Solar Energy UK states that electricity costs far more than gas, and that the enhanced efficiency of heat pumps does not make up for the difference, describing the change as probably the first ever update to building regulations to result in higher bills for consumers1. Developers can offset that rise by keeping solar in their designs1. For a household, the practical question of how much of its own energy a home can generate or store turns on whether solar is included, and the notional house specification no longer assumes it1. How many Scottish homes use mains gas for heating is set out in our guide to how Scottish homes are heated.
What happens next
New regulations come into force from the point of applying for a building warrant, so Solar Energy UK expects it to take a year or so before sites begin construction under the new regulations, and two to three years before the majority of new homes being built are to the new standard1. The Scottish Government announced in December 2022 that it would legislate for a Scottish Passivhaus equivalent by December 2024, which could mean a new version of the regulations in less than 12 months1. The European Commission announced a strengthened Energy Performance of Buildings Directive in December 2023, stating that installing solar energy installations will become the norm for new buildings1. 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 method1.