Everything you need to know about the SAP assessment process – a must-read for anyone embarking on a new build development.
What is a SAP calculation?
A SAP calculation refers to the Standard Assessment Procedure calculation. We use this in the UK to compare the energy and environmental performance of residential buildings. Every new residential development needs a SAP calculation, as do some specific renovations and extensions.
The SAP calculation provides a standardised way to evaluate the energy efficiency and environmental impact of a building. It considers various factors related to a building’s energy consumption and CO2 emissions: insulation, heating, ventilation, renewable energy sources, etc. Once all these factors are evaluated, you can use them to calculate the building’s SAP rating.
The SAP rating is expressed on a scale from 1 to 100, with higher numbers indicating better energy performance. The calculation considers the building’s fabric efficiency, space heating, hot water, lighting, ventilation, and renewable energy sources. The results of the SAP calculation are used to demonstrate compliance with building regulations. It’s the best way to assess the energy efficiency of a property. It also provides invaluable information to potential buyers or tenants.
Who needs a SAP calculation?
SAP calculations are required for various situations and individuals involved in residential construction. Here are some examples of who may need a SAP calculation:
- Developers and Builders
SAP calculations are mandatory for new residential developments. The developer or builder must always provide a SAP calculation to demonstrate compliance with building regulations. This is the case when it’s a single dwelling or when it’s a large housing development. These new build SAP calculations are called “SAP L1A“.
If you are planning to make significant renovations or extensions to your home, you may need a SAP calculation. This requirement ensures that the energy performance of the renovated or extended parts meets certain standards. A change of use SAP is also known as a “SAP L1B“.
- Architects and Designers
Architects and designers play a crucial role in ensuring that buildings meet energy efficiency standards. They often need SAP calculations as part of the design process. They use the SAP to understand how to optimise the building’s energy performance and meet regulations.
What is the difference between a Design SAP and an As-Built SAP assessment process?
“Design” and “As-Built” SAPs are needed at different stages of a building project. They also generally differ in the type of information they need to consider.
A Design SAP calculation is performed during the design stage of a building project. It involves assessing the energy and environmental performance of a building based on the design specifications, plans, and proposed materials. The Design SAP calculation helps architects, designers, and developers optimise the energy efficiency of the building by considering factors, such as insulation levels, heating systems, renewable energy sources, and other design elements. It provides an estimation of the building’s energy performance and compliance with building regulations before construction begins.
An As-Built SAP calculation happens after the completion of the construction project. This is when building work has finished and all information about materials used and systems installed is available. This calculation takes into account the actual construction details, including any deviations from the original design. The As-Built SAP calculation verifies and assesses the energy performance of the completed building. This ensures that it meets the required standards and regulations. It considers factors such as actual insulation levels, heating systems, ventilation, and renewable energy provisions as built. It doesn’t, however, focus on the design specifications.
What information is needed for a SAP assessment process?
- Building dimensions and floor plans
The size and layout of the building, including the floor area, number of storeys, and room dimensions, are needed.
- Construction materials and thermal properties
Details about the construction materials used for walls, roofs, floors, and windows are required. This includes information about insulation materials, thickness, U-values (thermal conductivity), and other relevant thermal properties.
- Heating and hot water systems
Information about the heating system, such as boiler type, efficiency, and controls, is needed. Details about hot water systems, including the type of cylinder and its insulation properties, are also required.
The type of ventilation system, whether natural or mechanical, needs to be specified. The ventilation rates, controls, and heat recovery systems, if present, should also be included.
The lighting system specification, including the type of lamps, fittings, and controls, should be provided.
- Renewable energy systems
If the building incorporates renewable energy systems, such as solar panels or heat pumps, their details, including efficiency and output, should be included.
- Air Tightness
The measured air permeability rate of the building envelope needs to be provided. (This is often referred to as air leakage.)
- Occupancy patterns
Information regarding the number of occupants, their usage patterns, and the hours of occupancy in different areas of the building is required.
- Shading and solar gains
Details about the building’s shading devices, orientation, and any external obstructions that may affect solar gains should be included.
- Miscellaneous factors
Other factors, such as the presence of open fires, secondary heating sources, and any additional energy-consuming equipment, should be accounted for.
What is the relationship between a SAP and an EPC?
The SAP calculation is the basis for generating the energy performance certificate (EPC). The calculated energy performance of the building, expressed as a SAP rating, is then translated into an EPC rating using a scale ranging from A (most efficient) to G (least efficient). The EPC then also includes additional information such as the estimated energy costs, recommendations for improving energy efficiency, and details about the property’s carbon emissions.
The EPC plays a role in meeting legal requirements, such as compliance with building regulations. It also contributes to the overall efforts to promote energy efficiency and reduce carbon emissions in the housing sector.
Our sustainability consultants have extensive experience in meeting regulatory requirements. They work hard to go beyond mere compliance with building regulations. Their approach is to reduce the amount of assumed data in each calculation to the bare minimum, meaning that our SAP calculations are as accurate as possible.
So if you need support with your own SAP calculation, get in touch with our friendly team.
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