SAP 10 Guide: What’s New in the Latest SAP Update

If you’re working in construction, design, or development, you’ve likely heard of SAP Calculations—a vital part of meeting UK Building Regulations. But if you’re still using SAP 2012 as your reference point, it’s time to get up to speed.

The latest version, known as SAP 10, introduces several important changes in how energy efficiency is assessed in new dwellings. Whether you’re an architect, builder, or self-builder, understanding these updates is essential for Part L compliance and improving EPC ratings.

In this guide, we’ll walk you through what SAP 10 is, what’s changed from SAP 2012, and how it affects your projects going forward.

✅ What Is SAP 10?

SAP stands for Standard Assessment Procedure. It’s the UK Government’s method for assessing and comparing the energy and environmental performance of homes.

SAP 10 is the latest version developed by BRE (Building Research Establishment), used alongside Approved Document Part L (2021), which came into effect on 15 June 2022.

SAP 10 is now the mandatory calculation method for all new dwellings in England and Wales.

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🆕 What’s New in SAP 10 Compared to SAP 2012?

SAP 10 introduces more accurate and realistic values in several key areas. Here are the most important updates you need to know:

🔌 1. Updated Carbon Emission Factors

The most talked-about change in SAP 10 is the update to CO₂ emission factors for fuels.

Fuel Type	SAP 2012 (kg CO₂/kWh)	SAP 10 (kg CO₂/kWh)
Electricity	0.519	0.136
Natural Gas	0.216	0.210

✅ What this means:
Electricity is now considered a much cleaner energy source. This benefits buildings that use:

Electric heating
Heat pumps
Solar PV systems

👉 Related reading: How to Prepare for SAP Calculations

🌡️ 2. Improved Internal Temperature Modelling

SAP 10 uses more detailed temperature assumptions based on real-world heating patterns and updated occupancy profiles.

✅ Why it matters:
More realistic heat usage data results in a more accurate assessment of heating demand, particularly for homes with modern controls or zoned heating.

💨 3. Air Source Heat Pump Support

SAP 10 includes better performance data for air source heat pumps.

Seasonal Coefficient of Performance (SCOP) is based on real product data
Heat pumps are now much more viable in SAP assessments

✅ Result:
Homes with well-specified ASHPs can more easily meet Part L carbon and energy targets.

🏡 4. Lighting Efficiency & Smart Controls

The assumed lighting energy use has decreased from 6.8 W/m² to 5.0 W/m²
Smart lighting controls and occupancy sensors are now recognised

✅ Benefit:
Incorporating LED lighting and smart controls can positively impact your Dwelling Emission Rate (DER).

🌍 5. Primary Energy Targets (Not Just CO₂)

Under the new Part L (2021), compliance is no longer based solely on CO₂. You must now meet three criteria:

Primary Energy Target (how much energy the dwelling uses)
Carbon Emission Target
Fabric Energy Efficiency Target (FEES)

👉 When Do You Need SAP Calculations?

✅ Why this matters:
The building’s fabric (insulation, glazing, airtightness) is now as important as the heating system.

🧮 SAP 10 in Practice: What You’ll See as a Client

When you request a SAP Calculation, your assessor will use SAP 10 to:

Model energy use from floorplans and specifications
Evaluate heating and ventilation systems
Consider lighting, renewable energy, insulation, and airtightness
Produce your Design Stage Report and As-Built SAP
Generate your Energy Performance Certificate (EPC)

⚠️ What to Watch Out For

Here’s how SAP 10 may impact your project:

Project Type	Impact of SAP 10
Electric-heated homes	More likely to pass under SAP 10 but could achieve lower EPC grades than gas boilers
Gas boiler homes	Less favourable due to higher CO₂ but still achieve better EPC grades
Extensions with glazing	Stricter performance expectations
Poor insulation/fabric	Harder to meet FEES and energy targets