SAP calculations and Part L compliance

New build homes and conversions require SAP calculations and EPCs to comply with the Building Regulations and meet certain planning requirements. This process spans the planning, design and construction phases to ensure compliance.

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FAQs

The five steps to Part L compliance

Step one: Information gathering

The developer, builder or self-builder provides the detailed plans and specifications for the design. This is usually created by the architect, but not always.

It’s important to provide as much information as possible, as early as you can. Unlike an Energy Performance Certificate for an existing home (rdSAP), a full SAP assessment can only be conducted where these detailed plans and specifications are provided for the whole house.

The following information is needed:

Plans of the dwelling: a site plan showing orientation, floor plans, elevations and section plans.
Specifications of all construction elements, heating and hot water systems, ventilation systems, lighting, renewable energy generation and battery storage.
Values and details for all thermal bridges (junctions between different construction elements, such as the wall and floor).
An airtightness target.

This information is gathered together prior to the next step.

Step two: Planning-stage SAP calculations are issued as part of the planning application

Many Local Planning Authorities including Cornwall, Plymouth and West Devon are increasingly asking for SAP calculations and won’t validate applications without them. If your Local Planning Authority doesn’t require a SAP calculation, you can skip this step.

To complete the first SAP calculation, takeoffs are completed of the plans and information from the specifications is input into the Standard Assessment Procedure (SAP) 10 software.

This produces three values for the overall design, which are used to check compliance against targets set in Part L of the Building Regulations:

Dwelling Fabric Energy Efficiency rate (DFEE).
Dwelling Primary Energy Rate (DPER).
Dwelling Emission Rate (DER).

If just one of these measures doesn’t meet Part L targets, then the whole building is non-compliant. In which case you will be supported to achieve compliance, iterating the design until the targets are achieved. For example you may need more insulation, a more efficient boiler or renewable generation.

It is important to remember that Part L not only includes these targets on overall performance, but minimum standards on individual elements, such as the efficiency of boilers or the U-values of walls and floors.

Your initial SAP calculation is produced and submitted to your Local Planning Authority. It is important to follow your local planning authority’s requirements closely, and fill out all of the forms they need.

Step three: As-designed SAP calculations are issued for building regulations

Once you’ve secured planning permission, you will be liaising with your Building Control Body to demonstrate Building Regulations compliance.

In order to comply with Part L of the Building Regulations, which relate to the conservation of fuel and power, you will need a SAP calculation and a Building Regulations England Part L (BREL) compliance report to evidence design-stage compliance.

Where any changes are made from the planning stage, these need to be reflected in the SAP calculation.

A Predicted Energy Assessment (PEA) can also be lodged, which is essentially an EPC for a home that has been designed but not built. This PEA can be used to market the home if you are selling off-plan.

Step four: The build process is completed and further information gathered along the way

The developer or builder completes the build. During this stage, the developer or builder is responsible for collecting evidence that the design specification has been followed, including photos and commissioning certificates. The photographic evidence requirements are set out in Appendix B of Part L.

After completion of the building fabric, an airtightness test must be completed by a competent person, and any commissioning certificates for building services systems gathered together for the next step.

Step five: As-built SAP calculations are issued and an EPC is lodged

A final SAP calculation is completed based on what has actually been built and the measured airtightness of the home. It’s important to let your SAP assessor know of any changes to the design, as these need to be reflected in the final SAP calculation.

Once calculated, an Energy Performance Certificate (EPC) is lodged and a Building Regulations England Part L (BREL) compliance report is produced to evidence as-built compliance to the Building Control Body.

Frequently asked questions

Why do I need a SAP calculation?

SAP calculations are required as part of the Building Regulations process. Increasingly, they play a role in the planning process too. Once your home is built, you are legally required to have an EPC. By having an EPC, tenants and potential buyers understand the energy efficiency of the home and can make informed decisions.

What is a SAP calculation?

A Standard Assessment Procedure (SAP) calculation is a standardised way to model the energy performance of a home in order to demonstrate compliance with the Building Regulations. The SAP model uses standard assumptions about how you use your home, so that the calculations are comparable.

SAP calculations underpin Energy Performance Certificates (EPCs) for new homes. You can think of an EPC in three ways:

1. An EPC is just like an energy label, but for homes. It’s a way of comparing one home with another.
2. It’s a dataset with different uses, including data warehouses on retrofit and national statistics about the UK’s housing stock.
3. It’s a set of recommendations to improve your home’s energy efficiency.

Who conducts a SAP calculation?

An Awarding Body of the Built Environment (ABBE) qualified On-Construction Domestic Energy Assessor (DEA) will carry out an assessment of your home. In our case, our new build SAP calculations and EPCs are accredited by Elmhurst Energy Systems.

How long is an EPC valid for?

After completion, your EPC is valid for 10 years. After this time, you need to get a new EPC.

How much does a SAP calculation cost?

A SAP calculation’s cost depends on the size and complexity of your home and any changes you may need to make the calculation along the way. Please get in touch to arrange a quote based on this.

What do you need to conduct a SAP calculation?

To produce an accurate and compliant SAP calculation, the following are needed:

– Plans of the dwelling: a site plan showing orientation, floor plans, elevations and section plans.
– Specifications of all construction elements, heating and hot water systems, ventilation systems, lighting, renewable energy generation and battery storage.
– Confirmation from the builder or developer that the specification has been followed, and any commissioning certificates you have (as-built stage).
– Values and details for all thermal bridges (junctions between different construction elements, such as the wall and floor).-
– An airtightness target (design stage) or test result (as-built stage)
– Construction photos that meet the photographic evidence requirements set out in Appendix B of Part L.

What catchment area do you cover?

Our catchment area for SAP calculations is England and Wales, although most of our work is with local planning authorities in the South West.

Why are EPCs different for new builds and existing homes?

It’s all about the methodology used to produce your EPC.

For existing homes, the Reduced Data Standard Assessment Procedure (RdSAP) methodology is used. This enables an EPC to be produced from a visual assessment alone and documentary evidence which is readily available. You can find out more about EPCs for existing homes here.

For new builds, a lot more information is available, including detailed plans and specifications. This means that the full Standard Assessment Procedure (SAP) methodology can be used, which is more robust than RdSAP.

I’ve read media coverage that SAP calculations and EPCs aren’t accurate – is this true?

When interpreting results, it is important to remember why these calculations are carried out. SAP calculations are used to check compliance rather than predict energy consumption, while EPCs are an asset rating system designed to compare the performance of different homes. These calculations don’t consider how the home is used. It also assumes a standard level of occupancy and heating levels. As such, it’s not unusual to feel it is not a true reflection of the performance of the home. For example, your energy bills may be much higher or lower than indicated on the EPC because of how you use your home.

If you have any questions about the EPC, feel free get in touch to discuss this in more detail.

I have another question that isn’t listed here.

If you have any questions about EPCs, feel free get in touch to discuss this in more detail.

Contact us directly by emailing office@morewoodsustainability.com or calling 01822 752 961.

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Using the form below ensures we have everything we need to provide an accurate quote, but if you prefer to contact us directly, please email office@morewoodsustainability.com or call 01822 752 961

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