New Homes and the Ban on Direct Emission Heating Systems in Scotland

From 1 April 2024, Scotland will ban direct emission heating systems—such as oil and gas boilers—in new homes. The New Build Heat Standard (NBHS) makes it illegal to install these systems in new build homes or other buildings applying for a building warrant after this date. You can find more details in the official New Build Heat Standard factsheet.

The Scottish Government has outlined some examples of zero-emission heating systems that might be used instead:

• Heat Pumps
• Heat Networks
• Electric (resistance) heating
• Solar Thermal
• 100% Hydrogen

While the regulations don’t provide a full list of what constitutes an emission-generating heating system, a press release from the Scottish Government confirms that oil, gas, and biomass heating systems fall under this category.

Ambiguities in the Regulations

Despite the progress, the regulations leave several points unclear:

1. Are Wood Stoves Banned?

The definition of a “direct emission heating system” refers to fixed combustion appliances used for heating or hot water. This raises the question: are wood stoves banned?

The Technical Handbook – Domestic mentions “emergency heating,” which includes fixed combustion appliances used only in emergencies, such as during a power cut. These systems are not subject to the same restrictions, and portable heaters are also excluded from regulation.

For frost protection, the regulations allow heating below 12W/m². For example, in a 45m² living room, this would permit a 540W gas heater, but most wood stoves—typically around 3-5kW—would exceed this limit.

Customers frequently ask if wood stoves fall under these exemptions. Some argue their stoves are decorative, not primary or secondary heating sources. However, in compliance software like SAP, wood stoves are treated as secondary heating, classed as bioenergy, and factored into the energy and running cost ratings of the house. Unless you can argue the stove is purely for emergency use, it’s likely to be banned.

Retrofitting wood stoves after the new build adds complexity. A building warrant is required for work involving chimneys, flues, or hearths. However, retrofitting an oil boiler might not require a warrant, as these are often exempt for balanced flue systems. Wood stoves, requiring a natural draw from a chimney or flue, would still need a warrant.

There’s also the question: if the intention is to ban wood stoves, why hasn’t this been clearly stated?

Wood stoves, while contributing to urban air quality issues, are incredibly useful in rural homes with heat pump systems. Heat pumps work harder in cold weather, drawing more power from the grid on the coldest days. In countries like Sweden, installing a heat pump in rural homes without a wood stove for backup is prohibited. Wood stoves also support local economies, particularly in the Highlands and Islands, where wood fuel production is sustainable and well-regulated.

An exemption for remote rural homes to have a wood burner in the living room would prevent backlash against the regulation’s primary aim: banning oil and gas boilers in new builds.

Trade bodies say wood stoves are banned. Building control officers say they’re not, provided they’re excluded from SAP calculations. The lack of clarity risks undermining the entire regulation.

2. Can Communal or District Heating Systems Use Gas or Oil?

The regulations exempt “fixed combustion appliance installations” that distribute heat through a network. This could allow gas or oil boilers to serve multiple dwellings, like blocks of flats.

While large district heating schemes are appropriate in some cases, this exemption might also cover smaller setups—for instance, two houses sharing a gas boiler. This creates a potential loophole where developers opt for communal gas systems over heat pumps, driven by lower installation costs.

Communal heating systems have a mixed track record. In London, mandatory communal heating schemes have led to large bills for residents, with heat loss from networks adding to costs. For small developments, individual heat pumps might offer lower running costs for homeowners, even if upfront costs are higher for the developer.

The legislation should make it clear where communal heating systems using gas or oil are appropriate to avoid creating a new industry of inefficient communal gas heating.

3. Conversions: What’s Allowed?

While the ban applies to new builds, it’s less clear for conversions.

The regulations state that direct emission systems can’t be installed in the part of the building being converted. However, existing oil or gas boilers can remain in unconverted areas. This creates potential loopholes, particularly for phased renovations.

Is Hydrogen the Solution?

Hydrogen is listed as a zero-emission option, but I remain sceptical about its viability for domestic heating.

While it’s technically possible to pipe green hydrogen into homes, the cost is high compared to heat pumps. Given the urgency of decarbonisation—Scotland needs to reduce heating emissions by 50-75% by 2030—hydrogen is too far behind to be a realistic solution. The hydrogen industry itself doesn’t expect widespread adoption before 2035.

Hydrogen is better suited for industrial heating and transport, where decarbonisation options are limited. Using it for domestic heating risks misallocating resources.

Burning hydrogen also produces up to six times the NOx emissions of natural gas. Allowing hydrogen boilers while banning wood stoves on air quality grounds seems inconsistent, especially in urban areas already struggling with poor air quality.

Conclusion

The New Build Heat Standard is a major step forward in decarbonising Scotland’s homes, but it needs refinement.

• Clearer guidance on wood stoves is essential, particularly for rural homes where they provide practical backup to heat pumps.
• Communal heating systems must be carefully regulated to avoid incentivising inefficient gas systems.
• Hydrogen’s role in decarbonisation needs to be more clearly defined, focusing on sectors where it offers the greatest benefit.

By addressing these points, the regulations can achieve their aim of eliminating oil and gas heating in new builds without unnecessary confusion or unintended consequences.

Dan Gates
MSc BEng IEng MCIBSE
Director, Luths Services Ltd

Dan is a Director/Engineer at Luths Services and a qualified energy assessor and certifier for building standards for energy in Scotland.