SAP Calculations for New Builds
SAP calculations are required for residential new build projects, in order to demonstrate compliance with Part L1a (and regional equivalents) of the Building Regulations/ Standards.
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What are SAP Calculations for new builds?
As part of the design process for new build projects, it’s essential to understand the energy efficiency and carbon emissions of the structure and building work through SAP assessments. Design stage SAP calculations for new build projects measure Dwelling Emission Rate (DER) and Dwelling Fabric Energy Efficiency. At the design stage of the build project, this calculation takes into consideration construction details such as construction materials and methods, space heating, cooling/heating systems, insulation, ventilation systems, climate conditions in the area where it’s located and efficiency of appliances/lighting. Our knowledgeable team of SAP assessors is here to help you make an informed decision that will be beneficial on many levels!
Once the energy assessment and SAP calculations for new build projects are complete, they are used to give the building an energy efficiency rating (the SAP rating), or energy performance certificate, which is then used to determine the amount of energy usage the building will need over its lifetime. These energy performance certificates in turn help inform decisions such as the type of heating and cooling systems to install, the insulation to use, and the type of windows and doors to use in order to reach the recommended energy performance and target fabric energy efficiency of a new build. In addition, the SAP calculation rating can be used to compare the running costs and efficiency of different new builds, allowing buyers to make more informed decisions.
What are Part L Calculations and why are they so important?
Part L of the Building Regulations provides guidance on how best to conserve fuel and energy in existing buildings. For new dwellings, Part L1a is dedicated to conserving power and fuel efficiency, with Part L1b looking at ways to improve the energy-efficiency of extensions and conversions in pre-existing properties.
In England and Wales, your residential building’s energy rating can be calculated using the Standard Assessment Procedure (SAP). This Energy Performance Certificate (EPC) is a government-approved method for measuring a building’s level of efficiency when it comes to meeting Part L1A Building Regulations.
Scotland has its own regulations – Section 6. Northern Ireland also follows requirements outlined in Part L1A.
Complete our full SAP Calculations checklist and submit it with your quote
Please note that, with multiple dwellings, if the construction and build specification details vary between plots, a separate SAP Calculations checklist must be completed for each type.



Why you need a SAP Calculation for new build property?
A SAP calculation and energy performance certificate (EPC) are mandatory requirements for any new build property in order to achieve compliance under current Building Regulations. A new build SAP is used at the design stage of building plans to calculate the predicted energy assessment of the building and to provide a report outlining any areas of improvement. As part of the construction details, the energy assessors also provide information on how much energy the building will use and the running costs during its lifetime. The calculation is essential for any new build property to comply with build standards as it helps ensure that the building work plans and specifications meet the current standards of efficiency and target emission rate.
What are TER and DER Calculations and when do I need these?
You may have come across mentions of a DER or TER in building regulations and planning conditions – but don’t worry if you’re unsure what they signify! These terms refer to the planned and actual Co2 emissions for new dwellings and will also help to determine whether a new building will meet its emission targets. No need to stress – we’ve got all the info you need to be fully informed.
Target Emission Rate (TER) is a metric used to determine the energy efficiency of a dwelling. The TER is calculated by taking into account the total energy consumption, including both space and water heating. The SAP TER is expressed in terms of kilowatt hours per square metre of floor area per year (kWh/m2/yr). New build projects in England are now assessed on both carbon target (TER) and fabric target (TFEE).
Dwelling Emission Rate (DER) is a metric used to measure the carbon dioxide emissions of a dwelling. The SAP DER is calculated by taking into account the total emissions from all energy sources, including both grid electricity and fuel (gas, oil, etc.). The SAP DER is expressed in terms of kilograms of carbon dioxide per square metre of floor area per year (kgCO2/m2/yr).
Our process
At Focus 360 Energy, our team of experienced professionals are committed to helping you with all your SAP Calculations for new build schemes across the UK. We’ve successfully assisted thousands of clients in their building plans to find compliant, cost-effective solutions that meet their needs.
Our team of knowledgeable SAP assessors can work hand-in-hand with your designers, contractors or architects to ensure a unified approach from beginning to end. Additionally, if desired, we can even take the lead in communicating with your Building Control Officer.
Simply download and complete our checklist and supply all the required information to us and we are able to offer a fast and efficient 5 day turnaround for SAP calculations on an extension or conversion. If this isn’t soon enough for you, then our expert team can further accelerate the process for just £75 + VAT.
Helpful information you may need to supply?
- Floor plans, sections & elevations
- Orientation e.g. site plan of existing elements
- Construction specification of existing walls, new structures, roofs and floors
- Specification for all windows
- Details on primary & secondary heating systems
- Renewable technology (if any)
Please call 0333 772 2798 if you have any questions.
What is included?
- All SAP calculation documentation required for compliance with the Building Regulations from Design (PEA) to On Construction
- Additional recommendations if required to ensure a pass is achieved every time
- Advice and support throughout the whole process
- Quick turnaround
- We are happy to deal directly with your Builder, Architect or Building Control Officer during our site visit
Frequently Asked Questions
What are SAP Calculations?
SAP stands for ‘Standard Assessment Procedure’ and is the government’s method for calculating the energy performance of dwellings. These calculations are only necessary for residential properties. The SAP calculations measure and determine a Target Emissions Rate (TER) and a Target Fabric Energy Efficiency (TFEE) rate.
How much is a SAP Calculation?
Our fees are typically based upon the size and complexity of a dwelling. We do prefer to offer a bespoke quotation on a job-by-job basis to give you the best price – So get in contact and send us your plans today!
Can I do a SAP Calculations?
SAP Calculations must be carried out by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government program. The Assessor must be certified under one of several accreditation schemes and is regularly audited to keep their certification.
What is required for a SAP Calculations Assessment?
Your SAP Assessor would advise you of exactly what is needed. Typically you would need the following:
- Floor plans, sections & elevations
- Orientation e.g. site plan
- Construction specification of walls, roofs and floors
- Specification for all windows
- Primary & secondary heating system details
- Renewable technology (if any)
SAP Calculations for Extensions
Under the latest building regulations, the quantity of glazing must be a maximum of 25% of the floor area of the new extension. Therefore over compensations in the thermal elements in other areas within the property will need to be made to show the CO2 emissions coming from the current house along with the proposed extension is not any worse when compared to the existing house and an extension whose glazing is within the allowed amount judged against Part L1B of the building regulations. You need SAP calculations to find solutions and demonstrate compliance.
Will I need SAP Calculations
You will require SAP calculations whether you are extending, converting or changing the use of a property. You will need to ensure that your specifications meet the requirements of building control.
- Building a new property
- Changing the use of an existing property (e.g, a barn conversion project, commercial building to residential)
- Extensions with more than 25% glazing
- Opening up the main house to an existing conservatory
- Extension where the extension is more than 50% of the original property wall area
- Garage conversions
- If requested by building control
This checklist is not exhaustive. If you’re unsure whether you need them contact us today for further information.
What happens if my design fails its SAP Assessment?
If your design fails its SAP Assessment, then you will need to revise the design to meet the requirements. Depending on the extent of the changes required, you may need to go through the assessment process again. In some cases, you may need to have additional testing done to verify the design’s performance. The SAP Assessors will provide guidance on the necessary steps to make your design meet the requirements.
SAP Calculations for all your building projects

Part L1A SAP Calculations for New Builds
All new dwellings must now have a SAP calculation performed at design stage in order to demonstrate compliance with Part L1A of the Building Regulations.

Part L1B SAP Calculations for Extensions
If you build an extension where the glazing is over 25% of the floor area, then we can undertake SAP Calculations to demonstrate Part L1B Building Regs compliance.

Part L1B SAP Calculations for Conversion
If you renovate a building such that there has been a material change in use, then we can undertake SAP Calculations to demonstrate Part L1B Building Regs compliance.
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