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For over a decade, SAP (Standard Assessment Procedure) 2012 was the standard framework for assessing the energy performance of dwellings across the UK. Every developer, architect, and builder relied on it when working to comply with Building Regulations Part L and to secure a valid Energy Performance Certificate (EPC).
The energy landscape, however, underwent significant shifts. With the National Grid becoming cleaner and the UK moving toward ambitious carbon reduction targets, the government introduced SAP 10 in 2022. This newer methodology provides more accurate data, more challenging compliance targets, and a greater focus on dwelling fabric energy efficiency.
In summary, the key changes are:
- SAP 2012 applied to projects registered before 15 June 2022, but could only be used if construction began by 15 June 2023.
- SAP 10 is now the current standard, underpinning Part L of the 2021 Building Regulations and applying to all new dwellings from June 2022 onwards.
- The updates reflect the UK’s decarbonised grid, making electric heating systems more favourable, while setting stricter requirements for fabric energy efficiency, carbon emissions, and renewable technologies.
For developers, the transition from SAP 2012 to SAP 10 means that strategies once considered sufficient, such as relying on gas boilers, no longer ensure compliance. Meeting today’s standards requires a fabric-first approach supported by low-carbon technologies, alongside early engagement with an experienced SAP assessor to keep projects on track.
At Falcon Energy, we provide the expertise to ensure compliance with confidence. Discover our SAP calculation services and contact us on 01403 253439 to book with our experienced team nationwide.
What are SAP calculations?
SAP stands for Standard Assessment Procedure, the government’s methodology for calculating the energy efficiency rating of a residential property. A SAP assessment uses detailed information about a proposed or existing home to model its expected energy consumption, energy costs, and environmental impact rating.
SAP calculations cover a wide range of factors, including:
- Heating systems, hot water, and ventilation systems
- Fabric energy efficiency, including insulation, external walls, floors, roofs, glazing, and thermal bridging
- Lighting specification and renewable technologies such as solar PV and battery storage
- Energy running costs, fuel costs, and reliance on fossil fuels
- Carbon emissions and dwelling emission rate
- Treatment of space cooling, heat solar gain quality, and water heating
The results determine whether a proposed dwelling meets the target emission rate (TER), target primary energy rate (TPER), and target fabric energy efficiency (TFEE) set by current building regulations. These calculations also directly inform the EPC rating a property receives upon completion.
To learn more about EPC ratings and certificates, including how much they cost, read our guide, ‘How Much Does An EPC Certificate Cost In The UK?‘.
Understanding SAP 2012
Before the introduction of SAP 10, the industry relied on SAP 2012 as the benchmark for assessing the energy performance of dwellings. For almost a decade, it guided the SAP calculations used to model thousands of newly built dwellings, providing building control officers with a framework to check compliance.
Some of the defining features of SAP 2012 included:
- Electricity was treated as highly carbon-intensive, so homes with electric heating were penalised in SAP ratings, while gas boilers were generally favoured for compliance
- Lower emphasis on fabric energy efficiency, with compliance focused more on emissions targets than insulation or airtightness.
- Limited recognition of low-energy lighting, ventilation systems, and heat pumps, so their contribution to energy efficiency was less accurately reflected.
- Reliance on the Target Emission Rate (TER) as the main compliance measure, without additional checks on primary energy use or building fabric performance.
While SAP 2012 provided a reliable framework for many years, the UK’s energy landscape underwent significant changes during its use. The National Grid became cleaner as more electricity was generated from low-carbon sources, such as wind and solar, rather than fossil fuels. At the same time, technologies like heat pumps and low-energy lighting advanced rapidly, meaning the old methodology no longer accurately reflected actual energy performance or the potential to reduce emissions. These changes highlighted the need for an updated approach, which led to the introduction of SAP 10.
The arrival of SAP 10
The government introduced SAP 10 as an updated home energy model to reflect the UK’s cleaner electricity grid, advances in building technology, and the drive to cut carbon emissions. It was designed to provide more accurate data and ensure assessments of new homes support national climate goals.
SAP 10 underpins Part L 2021 of the Building Regulations. As of 15 June 2022, all new dwellings have been required to comply with SAP 10. Projects that submitted plans before the deadline could continue under SAP 2012, provided construction commenced by 15 June 2023. Since that deadline has passed, all new projects must now comply with SAP 10.
The aim of SAP 10 is to keep assessments of home energy performance aligned with the UK’s net-zero ambitions. By using more accurate data on energy consumption and efficiency, it provides a clearer picture of how dwellings perform in practice and helps guide the design of homes that are fit for the future.
Key differences between SAP 2012 and SAP 10
To highlight the main updates, here’s a side-by-side comparison:
| Category | SAP 2012 | SAP 10 |
|---|---|---|
| Carbon Emissions | Electricity treated as highly carbon-intensive, so homes with electric heating were penalised and gas boilers were favoured. | Reflects the cleaner National Grid, making heat pumps and electric heating systems more favourable for compliance. |
| Primary Energy Rate | Based on the energy data available at the time, which favoured fossil fuels. | Introduces the Target Primary Energy Rate (TPER), reflecting today’s cleaner energy mix. |
| Fabric Energy Efficiency | Compliance focused mainly on emissions, with less emphasis on insulation or airtightness. | Introduces Target Fabric Energy Efficiency (TFEE) as a core compliance measure. |
| Heating Systems | Gas boilers were often the easiest way to achieve compliance. | Favours low-carbon heating systems such as heat pumps and hybrids. |
| Renewable Technologies | Gave limited recognition to solar PV and exporting energy. | Improved recognition of renewables, battery storage, and exporting to the grid. |
| Lighting | Assumed widespread use of conventional bulbs, undervaluing LEDs. | Reflects the shift to LED lighting, reducing energy consumption. |
| Space Cooling | Did not fully account for cooling demand. | Includes space cooling and solar gain, ensuring homes are ready for hotter summers as well as colder winters. |
| Compliance Targets | Relied mainly on the Target Emission Rate (TER). | Requires compliance with TER, TPER, and TFEE, creating a more rounded assessment. |
Why these differences matter:
- Energy sources – Under SAP 10, electricity is recognised as much cleaner than before, so gas boilers are less viable and heat pumps are now a more attractive option.
- Fabric energy efficiency – Homes must be built with stronger insulation, airtightness, and careful detailing of thermal bridges to meet the new Target Fabric Energy Efficiency (TFEE).
- Primary energy use – The introduction of the Target Primary Energy Rate (TPER) means compliance is now judged not only on carbon emissions but also on how efficiently energy is used.
- Climate readiness – By including space cooling and solar gain, SAP 10 ensures homes are designed to stay comfortable in both hotter summers and colder winters.
- Renewables – Technologies such as solar PV, battery storage, and energy export are now better recognised, helping developers meet compliance targets and reduce long-term operating costs.
Together, these changes mean compliance is no longer about meeting a single emissions figure; it’s about creating homes that deliver consistent, long-term energy efficiency.
What SAP 10 means for developers
For developers, the SAP 10 vs. SAP 2012 changes affect design decisions, budgets, and compliance strategies today. While the requirements are stricter, they also present opportunities to deliver homes that are more efficient, resilient, and attractive to buyers.
Implications for development
- Design – A fabric-first approach is now essential. High-quality insulation, airtightness, and careful detailing of thermal elements are critical to meeting TFEE and reducing energy demand.
- Costs – Meeting stricter standards may require more investment at the design stage, such as improved building fabric and advanced heating systems. However, these measures lower long-term energy costs and strengthen EPC ratings, making homes more attractive to buyers.
- Compliance – Older approaches, such as relying on gas boilers, may no longer achieve compliance. Without planning for SAP 10 early, developers risk costly redesigns, project delays, or failing building control checks.
Practical steps for developers
- Engage a SAP assessor early – Run design stage SAP calculations before plans are finalised to test compliance options and avoid costly redesigns.
- Prioritise fabric-first design – Invest in external walls, insulation, glazing, and airtightness to meet TFEE. Combined with modern heating systems and renewable technologies, this approach ensures both compliance and long-term energy efficiency.
- Reassess heating strategies – Transition from gas boilers to heat pumps or hybrid systems that align with the decarbonised National Grid.
- Plan for renewables and storage – Incorporate solar PV, battery storage, and energy exporting during design to strengthen compliance and reduce future operating costs.
- Design for year-round comfort – Address ventilation systems, space cooling, and solar gain to balance comfort and energy performance across the seasons.
By following these steps, developers can deliver new dwellings that not only comply with building regulations but also achieve lower running costs, stronger EPC ratings, and long-term compliance confidence.
Summary
SAP (Standard Assessment Procedure) is the government’s official method for assessing the energy performance of dwellings. SAP 2012 applied for projects registered before 15 June 2022, but only if construction began by 15 June 2023. Since then, all new dwellings must be assessed under SAP 10, which underpins Part L of the 2021 Building Regulations.
The most significant difference between SAP 10 and SAP 2012 is how electricity is handled. With the National Grid now cleaner, heat pumps and electric heating systems are far more favourable than gas boilers, and renewable technologies such as solar PV and battery storage play a larger role in compliance.
Developers must now meet three targets – Target Emission Rate (TER), Target Primary Energy Rate (TPER), and Target Fabric Energy Efficiency (TFEE) – and adopt a fabric-first strategy to ensure projects pass building regulations and achieve stronger EPC ratings.
Get a SAP calculations quote free from Falcon Energy
At Falcon Energy, we help developers achieve compliance with SAP 10. From early design through to project completion, our experienced energy assessors provide the expertise needed to ensure your build meets all requirements of Part L 2021 Building Regulations.
Our services include design stage SAP calculations, advice on improving energy efficiency ratings, and issuing the final Energy Performance Certificate (EPC) once the build is complete. By working with us, you can reduce long-term energy costs, integrate renewable technologies effectively, and move forward with confidence.
Contact us for a free, no-obligation SAP calculations quote and expert guidance on your next project.
SAP calculations FAQs
When did SAP 10 come into effect?
SAP 10 was introduced with the Part L 2021 Building Regulations and has applied to all newly built dwellings from 15 June 2022. Transitional arrangements allowed projects registered before this date to remain under SAP 2012, provided that construction commenced by 15 June 2023. That period has ended, so all new projects must now comply with SAP 10.
What is the biggest difference between SAP 2012 and SAP 10?
The most significant change is how electricity is treated. Under SAP 2012, electricity was considered highly carbon-intensive, meaning gas boilers often performed better in assessments. SAP 10 reflects the decarbonisation of the National Grid, making heat pumps and electric heating systems more favourable, while also giving more weight to renewable technologies.
Do existing homes need to be reassessed under SAP 10?
No, SAP calculations are generally only required for new dwellings, conversions, or certain types of building work. Existing homes do not need to be reassessed under SAP 10 unless they undergo significant changes that trigger a requirement for a new assessment. However, any new project started today must be assessed using SAP 10 to demonstrate compliance with current building regulations.