SAP stands for ‘Standard Assessment Procedure’ and is the government’s method for calculating the energy performance of dwellings.
SAP calculations are only necessary for residential properties. In England, your SAP calculations measure two elements; the Dwelling Emission Rate (DER) and Dwelling Fabric Energy Efficiency (DFEE).
The calculations determine a Target Emissions Rate (TER) and a Target Fabric Energy Efficiency (TFEE) rate. The DER and DFEE must be lower than the TER and TFEE. In Wales and Scotland, the report only measures the DER – although building regulation standards are stricter.
SAP calculations come in two formats; L1A (new builds) and L1B (extensions and conversions). The primary purpose of the calculations is to produce a new or updated Energy Performance Certificate (EPC).
Why do I need SAP Calculations?
How are they done?
- Site Plan
- Insulation type/thickness
- U-value of openings
- Specification of heating systems
- Hot water generation
- Percentage of low energy lighting
- Specification of ventilation system
- Renewable technologies
- Accredited construction details
How your SAP calculations are carried out will depend on whether your project is a new build, or an extension or conversion. In either instance, the calculations are divided into two reports: L1A SAP & L1B SAP:
L1A SAP calculations information
Design Stage Report
- Before construction begins, our team will assess and approve the construction details of the property
- This data is input into SAP calculations software in order to produce TER and TFEE rates and to demonstrate that the building is DER and DFEE compliant
- A ‘predicted energy assessment’ is produced
As Built Report
- Once the building is complete, the construction details are re-assessed and any final details included, such as boiler model or air tightness score
- This final report produced the EPC
L1B SAP Calculations Information
- Our team will assess the construction details of the entire property, plus the proposed extension or conversion. From this, they will create a report with benchmarked data
- To create the report, the construction detail data is input into SAP calculations software in order to produce notional TER and TFEE rates and DER and DFEE measurements
- The proposed report will use the benchmarked data for existing elements. For any new or upgraded elements, our team will assess the actual performance data
- This data is then input into SAP calculations software in order to produce the proposed TER and TFEE rates and DER and DFEE measurements
- The performance values of the proposed elements must be lower than the benchmarked standards in order for the property to pass
- In addition to this, the overall DER and DFEE measurements must be lower in the proposed report than in the notional report.
- If the buildings SAP calculations demonstrate that the building’s performance values are all lower in the proposed report than the notional report, a new EPC is produced, replacing the property’s existing EPC
When should a sap calculation be carried out?
How long will it take?
What happens if my building fails?
Take a look at a case study from when we did a SAP calculation for a plot of new build homes in Nuneaton HERE.