Last Updated on October 12, 2026 by daxom

SAP 10.2 and Electric Combi Boilers: What You Need to Know

SAP 10.2 is an important consideration when assessing the energy performance of new and existing homes in the UK. For homeowners, developers and heating professionals considering a Daxom electric combi boiler, understanding how SAP calculations work can help when choosing an appropriate heating system.

In this guide, we explain what SAP 10.2 means, how the methodology has changed, and what the updated electricity carbon factors mean for electric boilers.

What Is SAP?

SAP stands for Standard Assessment Procedure. It is the methodology used to assess the energy performance of residential properties in the UK and is used to produce an Energy Performance Certificate (EPC).

SAP considers a range of factors affecting a property’s energy performance, including:

• The building’s construction and insulation
• Heating and hot water systems
• Ventilation
• Renewable energy technologies
• Lighting
• Energy use
• Fuel types and associated carbon emissions

The SAP methodology has been updated several times since its introduction in 1995. SAP 10.2 was introduced as a further update to reflect changes in energy generation, technology and household energy use.

What Is SAP 10.2?

SAP 10.2 is an updated version of the Standard Assessment Procedure. One of the significant changes affecting electric heating is the updated carbon factor for electricity used in SAP calculations.

The electricity grid has changed considerably over recent years, with increased generation from renewable sources such as wind and solar. As electricity generation becomes less carbon-intensive, the carbon factor used in energy assessments needs to reflect those changes.

This is particularly relevant to electric boilers, because they use electricity rather than directly burning gas or oil.

How Does SAP 10.2 Affect Electric Boilers?

Under earlier SAP methodology, electricity was assigned a considerably higher carbon factor than mains gas. This could make electric heating appear less favourable in SAP calculations.

SAP 10.2 introduced a substantially lower electricity carbon factor, reflecting the changing UK electricity generation mix.

The figures used in SAP calculations can change as the methodology is updated, so it is important to use the current applicable SAP methodology when assessing a property rather than relying on historical figures.

For developers and heating professionals, this change can be particularly relevant when comparing electric heating systems with gas heating during the design and assessment of a property.

Why Is SAP Important for Electric Combi Boilers?

An electric combi boiler provides central heating and domestic hot water using electricity.

Because there is no combustion of gas or oil at the boiler, electric boilers can be an option for properties where a mains gas connection is unavailable or where an alternative to fossil-fuel heating is required.

However, the suitability of an electric boiler should not be determined by SAP alone.

Other factors need to be considered, including:

• Property heat loss
• Boiler output
• Hot water requirements
• Electrical supply capacity
• Insulation levels
• Heating controls
• Property size and design
• Renewable technologies such as solar PV

A correctly sized heating system is essential for good performance and energy efficiency.

Electric Boilers and the UK’s Changing Energy Mix

The UK’s electricity generation mix has changed significantly over time, with renewable generation playing an increasingly important role.

This is relevant to electric heating because the carbon intensity associated with electricity is not fixed. As the electricity grid incorporates more low-carbon generation, electricity can become a lower-carbon energy source than it was under older assessment assumptions.

Electric boilers can also be combined with technologies such as solar photovoltaic (PV) panels to allow a property to generate some of its own electricity.

For more information, see our guide to running an electric combi boiler with solar panels.

Are Electric Boilers a Good Choice for New Build Properties?

Electric heating can be particularly relevant to new-build developments where developers are considering alternatives to traditional gas heating.

The suitability of an electric boiler will depend on the individual project and the requirements of the building. SAP calculations, Building Regulations, electrical infrastructure, heat loss and the overall energy strategy should all be considered during the design stage.

It is also important to distinguish between SAP calculations, EPC ratings and Building Regulations requirements. They are related, but they are not the same thing.

Professional advice should be obtained for projects where heating-system selection affects compliance or energy-performance calculations.

Can an Electric Boiler Improve an EPC Rating?

An electric boiler does not automatically result in a higher EPC rating.

An EPC is based on the overall energy performance of the property, and the heating system is only one part of the assessment.

Factors such as insulation, windows, heating controls, hot water provision and renewable energy systems can all influence the result.

For this reason, the best approach is to assess the whole building, rather than choosing a heating system based solely on its potential impact on an EPC.

What Are the Benefits of an Electric Combi Boiler?

Depending on the property and application, an electric combi boiler can offer several advantages:

No Mains Gas Required

Electric boilers do not require a mains gas connection, making them an option for properties without access to the gas network.

Compact Installation

Electric boilers can have a compact design and do not require a conventional flue for combustion gases.

No On-Site Combustion

An electric boiler does not burn gas or oil at the point of use.

Compatible with Renewable Electricity

Electric boilers can be integrated into wider home energy systems that include technologies such as solar PV.

Suitable for a Range of Applications

Electric heating can be considered for new builds, extensions, properties without mains gas and projects where an electric heating solution is preferred.

The correct boiler output and system design remain essential to achieving good performance.

SAP 10.2 and Electric Boilers: Key Takeaways

SAP 10.2 reflects changes in the UK’s energy system and includes updated assumptions about electricity generation and carbon emissions.

For electric combi boilers, this is important because the carbon intensity attributed to electricity has a significant influence on energy-performance calculations.

However, SAP should be considered as part of the wider building design. Boiler sizing, insulation, heat loss, controls, electrical capacity and renewable technologies should all be considered when selecting a heating system.

As the UK continues to increase renewable electricity generation and reduce reliance on fossil fuels, electric heating technologies are likely to remain an important consideration for suitable properties.

Frequently Asked Questions

What does SAP 10.2 mean?

SAP 10.2 is an updated version of the UK’s Standard Assessment Procedure used to assess the energy performance of residential properties and support EPC calculations.

Does SAP 10.2 favour electric boilers?

SAP 10.2 updated the assumptions used for electricity, including its carbon factor. However, whether an electric boiler is suitable or beneficial for a particular property depends on the complete building and heating-system design.

Are electric boilers suitable for homes without mains gas?

Yes. Because electric boilers use electricity rather than mains gas, they can be considered for properties that do not have access to the gas network.

Can an electric boiler work with solar panels?

Yes. Solar PV panels can generate electricity that can be used within a property, including to supply an electric boiler when sufficient solar generation is available.

Does an electric boiler automatically improve an EPC rating?

No. An EPC rating is based on the overall energy performance of a property. The heating system is one factor among several that can affect the result.

Is SAP 10.2 the same as an EPC?

No. SAP is the assessment methodology used to calculate the energy performance of a dwelling, while an EPC is the certificate that records the property’s energy-performance rating and related information.

Conclusion

SAP 10.2 and electric boilers are increasingly relevant topics for homeowners, developers and heating professionals considering modern electric heating systems.

The updated SAP methodology reflects changes in electricity generation and the growing contribution of renewable energy. However, choosing an electric combi boiler should always involve a wider assessment of the property’s heating demand, insulation, electrical supply and overall energy strategy.

If you are considering a Daxom electric combi boiler, contact Daxom for further information about available electric heating solutions and boiler specifications.