SAP Calculations
The Standard Assessment Procedure (SAP) is a government-approved methodology used to measure the energy efficiency and environmental impact of residential properties. These assessments are essential for producing an Energy Performance Certificate (EPC), which provides detailed information about a building’s energy consumption and carbon dioxide emissions. SAP calculations are required for new residential properties, conversions, and certain extensions.
What is a SAP Calculation?
A SAP calculation is a Standard Assessment Procedure calculation. These assessments are crucial for producing a Predicted Energy Assessment (PEA) and an Energy Performance Certificate (EPC), demonstrating that your property complies with Part L (conservation of fuel and power) of the Building Regulations: Part L1A for new builds and Part L1B for conversions and extensions of existing buildings. Building regulations require that a SAP calculation be submitted before the commencement of construction.
These calculations measure two key elements: the Dwelling Emission Rate (DER) and the Dwelling Fabric Energy Efficiency (DFEE). They determine a Target Emission Rate (TER) and a Target Fabric Energy Efficiency (TFEE). To meet compliance, the DER and DFEE must be lower than the TER and TFEE.
A SAP assessment will produce a SAP rating ranging from 1 to 100+, estimating the annual energy-related cost of a dwelling. Higher ratings indicate better energy efficiency, leading to lower running costs, with 100 representing zero energy costs. If the rating exceeds 100, the dwelling is self-sustaining and a net exporter of energy. Thus, a higher SAP score corresponds to lower fuel costs and reduced carbon emissions.
Do I Need a SAP Calculation?
A SAP calculation is required for new builds, conversions, and some extensions. It is vital to prove that your property meets the carbon emissions and fabric performance standards set out in Part L of the Building Regulations. Additionally, it demonstrates your compliance with planning conditions related to carbon and energy savings. Your building control officer will require both your SAP and EPC to sign off on your building.
Under Part L1A, all new build properties require SAP calculations. To achieve compliance, the building must meet the following criteria: The Dwelling Fabric Energy Efficiency (DFEE) must not exceed the Target Fabric Energy Efficiency (TFEE), and the Dwelling Emission Rate (DER) must not exceed the Target Emission Rate (TER).
For Part L1B:
An extension will need a SAP calculation if it meets any of the following criteria:
- It has more than the permitted amount of glazing, which must not exceed 25% of the floor area.
- If you change a conservatory roof to a fully insulated roof, it effectively becomes an over-glazed extension.
- Modern extensions with roof lights and bi-fold doors often have significant glazing, leading to high heat losses.
SAP calculations demonstrate compliance by one of the following methods:
- Area-Weighted U-Value / Heat Loss Calculations
- The Entire House Method
A conversion will require a SAP calculation if it meets the following criteria:
- Dwelling change of use – e.g., converting a commercial building to residential accommodation.
- Increasing or decreasing the number of dwellings – e.g., converting a single property into self-contained flats.
How Are SAP Calculations Completed?
A SAP calculation measures the energy and environmental performance of your dwelling and predicts the amount of energy your development is likely to consume. Your SAP assessment will analyze:
- Construction materials
- Thermal insulation
- The efficiency of heating systems
- The fuel used for water and space heating, lighting, and ventilation
- Solar gains from openings in the property
- Renewable energy technologies
- Air leakage
The information necessary for a SAP calculation includes:
- Floor plans
- Elevation and sectional drawings
- Insulation details and other thermal elements
- Breakdown of ventilation systems
- Internal lighting
- Heating patterns
- Household size
- Domestic hot water estimates
- Use of renewable technologies
- Heating system performance
- Primary and secondary space heating
- Target fabric energy efficiency
- Potential sources of heat loss, such as thermal bridging
The Design Stage
Before any construction begins, design-stage SAP calculations that show a pass for all criteria must be submitted to Building Control. These calculations are used by Building Control to verify that the proposed drawings and specifications for the development satisfy the compliance criteria of Approved Document L1. If you do not achieve a pass, we can provide solutions to ensure your designs meet compliance. These could include changes to the thermal insulation of the building fabric, improvements to the air leakage characteristics of the dwelling, or changes to the heating and hot water systems. Once these changes are agreed upon, we will issue design-stage SAP reports for submission to Building Control.
The As-Built Stage
Upon project completion, as-built SAP calculations must be submitted to Building Control before the final sign-off of the development. These calculations update the design-stage SAP calculations to reflect the results of the air leakage test, any design alterations, and the technical data for the installed heating and hot water systems. Once completed, we will provide as-built SAP reports and an Energy Performance Certificate for submission to Building Control.
Summary
SAP calculations are crucial for assessing the energy performance of residential buildings in the UK. They measure a building’s energy efficiency and provide a rating on a scale from 1 to 100+. These calculations are required for new builds, conversions, and certain extensions to ensure compliance with Building Regulations. They estimate a property’s energy usage, carbon dioxide emissions, and the cost of heating, lighting, and hot water. A SAP assessment can help homeowners and developers create more sustainable, energy-efficient homes, reducing environmental impact and running costs.
Our SAP experts understand how to perform assessments correctly and will work closely with you to ensure that your building is properly evaluated before construction. Whether you’re planning a new build or making changes to an existing property, obtaining SAP calculations early in the process can ensure your project meets the necessary energy efficiency standards.
If you want to learn more about what a SAP assessment entails or need more information about our services and pricing, contact us today. Our experts are always ready to assist you.
