SAP Calculations: The Definitive Guide for New Builds
## What are SAP Calculations?
Standard Assessment Procedure (SAP) is the government's approved methodology for assessing and comparing the energy and environmental performance of dwellings.
If you are building a new home, converting a building into a dwelling, or building a highly glazed extension, you will almost certainly need a SAP calculation to prove compliance with Building Regulations Part L.
### Why Do You Need SAP Calculations?
SAP calculations are required by Building Control. They demonstrate that the dwelling meets the target limits for carbon emissions (Target Emission Rate - TER) and fabric energy efficiency (Target Fabric Energy Efficiency - TFEE).
The final On-Construction EPC (OCEPC) cannot be issued without a passing SAP calculation.
### When Should SAP Be Done?
SAP is a two-stage process:
**1. Design Stage (Before building starts)**
You must submit a design-stage SAP calculation to Building Control before construction begins. This ensures that the planned specification (insulation, heating, glazing) will pass the regulations. Modifying the design on paper is cheap; fixing a non-compliant building that is already built is incredibly expensive.
**2. As-Built Stage (When building is complete)**
Once the building is finished and the air tightness test has been conducted, the SAP assessor updates the calculation with the actual tested air permeability score and any changes made during construction. If it passes, the final EPC is lodged.
### What Information Does the Assessor Need?
To conduct an accurate SAP calculation, the assessor needs:
- Scaled architectural floor plans, elevations, and sections
- Detailed construction specification (U-values for walls, roof, floor)
- Details of all windows and doors (U-values, g-values)
- The primary and secondary heating systems (make and model of boiler/heat pump)
- Hot water storage details
- Ventilation strategy (e.g., MVHR, extractor fans)
- Details of any renewable technologies (e.g., Solar PV array size and orientation)
### How to Pass Part L
The 2021 update to Part L (implemented in 2022) significantly tightened the targets. To pass, most new builds now require a combination of high-performance fabric (low U-values), good air tightness, and low-carbon technology (such as solar PV panels, waste water heat recovery, or an air source heat pump).
If your design fails, a good SAP assessor will work with you to identify the most cost-effective ways to improve the specification and achieve a pass.
[Get a quote for your SAP calculations](/services/new-build-epc) from our accredited team today.
Standard Assessment Procedure (SAP) is the government's approved methodology for assessing and comparing the energy and environmental performance of dwellings.
If you are building a new home, converting a building into a dwelling, or building a highly glazed extension, you will almost certainly need a SAP calculation to prove compliance with Building Regulations Part L.
### Why Do You Need SAP Calculations?
SAP calculations are required by Building Control. They demonstrate that the dwelling meets the target limits for carbon emissions (Target Emission Rate - TER) and fabric energy efficiency (Target Fabric Energy Efficiency - TFEE).
The final On-Construction EPC (OCEPC) cannot be issued without a passing SAP calculation.
### When Should SAP Be Done?
SAP is a two-stage process:
**1. Design Stage (Before building starts)**
You must submit a design-stage SAP calculation to Building Control before construction begins. This ensures that the planned specification (insulation, heating, glazing) will pass the regulations. Modifying the design on paper is cheap; fixing a non-compliant building that is already built is incredibly expensive.
**2. As-Built Stage (When building is complete)**
Once the building is finished and the air tightness test has been conducted, the SAP assessor updates the calculation with the actual tested air permeability score and any changes made during construction. If it passes, the final EPC is lodged.
### What Information Does the Assessor Need?
To conduct an accurate SAP calculation, the assessor needs:
- Scaled architectural floor plans, elevations, and sections
- Detailed construction specification (U-values for walls, roof, floor)
- Details of all windows and doors (U-values, g-values)
- The primary and secondary heating systems (make and model of boiler/heat pump)
- Hot water storage details
- Ventilation strategy (e.g., MVHR, extractor fans)
- Details of any renewable technologies (e.g., Solar PV array size and orientation)
### How to Pass Part L
The 2021 update to Part L (implemented in 2022) significantly tightened the targets. To pass, most new builds now require a combination of high-performance fabric (low U-values), good air tightness, and low-carbon technology (such as solar PV panels, waste water heat recovery, or an air source heat pump).
If your design fails, a good SAP assessor will work with you to identify the most cost-effective ways to improve the specification and achieve a pass.
[Get a quote for your SAP calculations](/services/new-build-epc) from our accredited team today.