SAP Calculations

SAP Assessments

What Is A SAP Calculation?

SAP calculations for domestic properties helps you calculate how much energy your home is likely to use, as well as the level of CO2 emissions it will produce.

However confusing they might appear, SAP Calculations are a core element in the design of any residential scheme, and an essential part of existing Building Regulations.

Under Part L of the building and planning regulations in the UK, new homes must have been through an SAP Assessment, and as a result of this, most developers have a working knowledge of their content.

However, first-time builders, developers, and self-builders are sometimes challenged by the process of SAP Calculations in the building and planning phase.

SAP Calculations

The role of SAP calculations for buildings is threefold:

  1. To calculate the energy-related costs of a dwelling. The resulting figure is called a SAP Rating.
  2. To evidence compliance with building regulations (Part L).
  3. To generate data required to put together an Energy Performance Certificate (EPC).

A slightly different assessment may also be required when building an extension or conversion. If you are building in Scotland, bear in mind that different requirements apply, so please make additional checks.

SAP is an abbreviation for Standard Assessment Procedure. SAP is the single, government-approved system for determining a new home’s energy rating. Companies approved to make SAP Calculations have to be accredited and registered with a certification body.

SAP Ratings

SAP Ratings make for easy comparison between homes, allowing potential buyers to choose between dwellings having different SAP scores. A SAP Calculation scale runs from 1 and 100, where 100 represents no energy costs at all. The higher a dwelling’s SAP rating, the lower the fuel bills and, significantly in this era of climate change, the lower the emissions of CO2.

Dwellings can achieve an SAP assessment rating over 100; however, this would mean they are capable of exporting surplus energy by having solar panels, for instance.

Factors taken into account when calculating energy costs in a SAP calculation include:

  • Construction of the dwelling
  • The heating system
  • Internal lighting
  • Renewable technologies.

However, it is worth noting that SAP calculations do not include the energy consumption of household appliances such as ovens, TVs, and refrigerators.

What is a SAP Calculation

Why do you need a SAP Calculation?

No one is entitled to let or even market property for intended sale unless the relevant builder can demonstrate conforming with a SAP rating calculation.

SAP matters for other reasons too. An assessor can play an active role in assisting designers and architects in creating the optimum energy profile of new builds – minimising energy use and pushing down carbon emissions.

Proper SAP certification reveals differences in the relative effectiveness of various types of construction and home heating models, which in turn informs delivery to the end-user.

A further critical point concerns the sharing of SAP data. SAP ratings lay bare the energy performance of relative dwellings and are made freely available through the EPC document.

To pass the SAP Assessment, a builder must:

  • Quantify the heat retention and solar gain properties of the dwelling.
  • Demonstrate the dwelling’s construction quality.
  • Provide evidence of the commissioning of systems.
  • Calculate the dwelling’s predicted CO2 emissions.

Emissions calculations are critical in SAP calculations

Crucial emissions targets calculate through what are known as DER/TER numbers. Calculations of CO₂ emission levels result from a comparison of the Target Emission Rate (TER) and a prediction of the Dwelling Emission Rate (DER). A target rate determines following the application of baseline measurements to a representation of a roughly similar house.

Councils increasingly employ CO₂ calculations to meet their sustainability targets and to further energy policy. Providing an accurate SAP Calculation when submitting planning applications to local authorities demonstrates that your new build, extension, or conversion complies with energy efficiency guidance in UK building regulations.

Fabric Energy Efficiency in SAP Calculations

A requirement to assess the Fabric Energy Efficiency (FEE) of all new homes was brought in in England for dwellings built post-April 2014.

FEE does not measure carbon. It records energy requirements in kilowatt-hours per square metre per annum. How effectively dwellings retain heat closely relates to their CO2 emissions — a separate measure subject to compliance testing.

Fabric Energy Efficiency is assessed using DFEE/TFEE figures, with targets set in SAP calculations using reference values relating to property size.

How Do SAP Calculations Work?

It is essential that all technical specifications from which SAP inspectors derive their measurements are comprehensively detailed, highly accurate, and professionally determined.

Drawings should be to scale and depict all elevations. From the technical specifications of such elements as ventilation, heating, and AC systems, assessors construct models of homes using SAP computer applications. Manufacturers’ databases are then accessed and specific product details incorporated.

Every thermal detail of the building’s fabric is also added as are the details of any renewable or cooling technology.

The length of time it takes to get your application passed depends on your construction timeline. Briary Energy has a target for completion of between 5–10 working days after submission of a request.

A finished set of SAP calculations constitutes a comprehensive, fully-accessible database of building knowledge on everything from heat loss to fluctuations in seasonal demand.

How Do I Make My Building Pass A SAP Assessment?

Nowadays, starting work before you have a design is challenging. Whereas in the past, architects and developers all but ignored SAP Calculations, changes to SAP in 2005, 2009, and 2014 now ensure that SAP regulatory compliance is much tougher to attain.

Unsurprisingly, given the current climate crisis, and resultant EU and UK environmental policies, control of CO2 emission targets has tightened enormously. A typical new build designed just 5 years ago has a good chance of failing today’s regulations.

One of the most common FAQs on this subject is, ‘Why do some builds fail and others pass?’ There’s no easy answer, but a variety of factors can contribute to a rejection: Boiler size, for example. Or a non-compliant wall junction. Even the thickness of floor insulation on a floor, or the direction in which a house points!

Some factors lie beyond client control – if a dwelling has no connection to mains gas; for example, the owners might have to use oil or gas. Fossil fuels cost more and generate significant CO2 emissions, and because Target Emission Rates are based on mains gas, you may lose out.

How long do SAP Calculations take to complete?

The length of time it takes to get your application passed depends on your construction timeline. Briary Energy has a target for completion of between 5–10 working days after submission of a request.

And if my building fails?

The bottom line? It’s illegal to sell or even rent a property that doesn’t have a valid EPC. It is, therefore, essential that your building passes its SAP and that all SAP calculations are complete before starting any building work. Should the dwelling fall short of the SAP calculations building regulations standards, our SAP specialists can offer advice on how to improve.

The longer you leave things, the more you restrict your ability to make changes. And the greater the risk of higher bills, as the range of changes available becomes more limited. We aim to provide comprehensive support and guidance throughout the entire SAP process. Though many companies provide calculations only, we offer customers consultancy services to ensure they have everything they need to pass.

What is a SAP rating?

A SAP rating is the measurement needed to produce a Predicted Energy Assessment and On Construction Energy Performance Certificate. Building Regulations allow a SAP calculation and a predicted EPC to be submitted for new buildings before construction begins.

What does SAP stand for?

SAP is Standard Assessment Procedure. It’s the only legal, government-approved method for determining a new home’s energy rating. SAP assessors must be accredited with a certification body.

Do I need a SAP calculation for an extension?

SAP calculations are often required for extensions, especially if your proposal includes large glazing areas. Building Regulations Part L1b requires new glazing areas to account for no more than 25 percent of new floor area.

How much do SAP calculations cost?

Our SAP calculation cost for New Builds and Conversions are priced from £50+VAT for one unit and from £30+VAT for each multiple units on one site. Our price includes limitless advice on how best to get the project to meet Part L of building regulations.

What is Part L of the Building Regulations?

Part L is a building regulation that covers new construction schemes, which restricts the use of a dwelling or all other buildings in England. This sets new and existing buildings’ energy efficiency and carbon emissions requirements.

SAP Calculations are carried out during two stages, where communication with the SAP assessor is key to gaining compliance:

Design stage – where you will need to make a submission to Building Control before any work begins

Built stage – once the dwelling has been completed and established

The two submissions of SAP Calculations are used by Building Control to check your compliance in accordance with the related targets.

There must be evidence when it comes to your product specification – evidence that the design specification has been met. When you reach the ‘As Built’ stage of SAP Calculations, you will also need an EPC for the dwelling as well.

Why not try our U-Value resource.

At Briary Energy Ltd, we are building energy consultants with acknowledged experience in carrying out SAP assessments, preparing energy statements, performing air permeability testing, and more. If you are working on a new building, an extension, or a conversion project, call us today for expert advice on energy efficiency on 020 3397 1373, or contact us through our website at We’d be delighted to assist.

Frequently Asked Questions

SAP is the acronym for the Standard Assessment Procedure, a methodology drawn up by the Government to evaluate and compare the performance of buildings in terms of energy and environmental impacts. The purpose of the SAP estimation is to ensure that new buildings conform both to the Building Regulations and all current energy and environmental standards.

  1. Build a SAP calculation into the design stage.
  2. Choose an appropriate building fabric.
  3. Look at ways of lowering the thermal mass.
  4. Make use of renewables.
  5. Install party wall insulation.
  6. Upgrade heating controls.
  7. Fit suitably low energy light bulbs.

If you are converting a commercial property into a dwelling place, developing a new dwelling from an existing one, or converting a single dwelling into multiple flats, then you are more than likely to need SAP calculations for building control, under Part L1B of the Building Regulations.

There are three main measures that make up a SAP report:
1) Calculated use of energy by unit floor area;
2) The SAP rating: an energy efficiency rating based on the fuel cost of running the building; and
3) CO2 emissions (the Environmental Impact Rating).

SAP calculations in the UK are valid for ten years. Once this period is up and provided it’s been confirmed that a SAP has taken place in the past, a Reduced Data Standard Assessment Procedure (RDSAP) can be carried out.

You won’t require any additional SAP energy rating calculations for extensions to a building unless the glazing within it exceeds 25% of the new total floor area. Any existing windows that are removed in the process of building the extension can be subtracted from the equation.

An EPC outlines a building’s energy efficiency and is required for most properties being sold or leased. Any new home or building being converted into a dwelling needs a SAP analysis outlining its energy performance, which is calculated from construction plans and architects’ drawings. These calculations then form the basis of the EPC.

The SAP energy rating states the energy performance of a home. The rating is on a scale from 1 – 100+. The higher the rating, the lower the energy cost and resulting CO2 emissions. If the SAP rating is 100, the building has zero energy cost, and anything over 100 means energy is being exported back into the national grid.

Building Regulations state that any new residential development or conversion to a dwelling must have a SAP assessment carried out. Its purpose is to demonstrate the energy and environmental performance of a building and should be built into every project’s design phase.

If you need advice with the SAP calculations new build projects require, contact the experts at Briary Energy.

The higher the SAP rating, the more energy-efficient a property is. The scale is as follows:

A = 92-100 SAP points.
B = 81-91.
C = 69-80.
D = 55-68.
E = 39-54.
F = 21-38.
G = 1-20.

Since April 2018, landlords cannot lease properties rated below E; and vendors find that less energy-efficient properties command lower sale prices.

The All-Important Guide to the SAP Assessment

The Standard Assessment Procedure (SAP) is required by Part L of the Building Regulations for all new-build homes and conversions to dwelling places. You should have your SAP computation done as early as possible, preferably in the project’s design phase. The assessment examines:
  • The building’s fabric and structure;
  • Its hot water and heating systems;
  • Its lighting systems; and
  • Its production of renewable energy (e.g., solar panels).
The higher the score, the better. The rating is calculated through examination of architects’ plans and construction documents. You may be required to make changes if your building falls short.

How to work out a SAP score

A SAP rating is calculated from a new-build’s drawing’s plans and specifications for the development. The assessor looks at the dwelling’s total floor area, storey heights, the areas of the floors, walls, and roofs where heat may be lost, the dimensions of windows and doors, and so on. Data about ventilation, main and secondary space heating, how hot water is generated, energy-efficient lighting, and any renewable technologies like solar water heating and solar panels are all taken into account. The information is input into specialist software that calculates a Predicted Energy Assessment, which gives an overall energy performance rating for the building.

How Can You Get a Satisfactory SAP Calculation for Your Building

These ideas will help you generate satisfactory SAP calculations for new build projects:
  1. Ensure party walls are insulated, especially relevant for flats or mid-terrace houses.
  2. Add enhanced heating controls, such as weather compensators and twin zone controls.
  3. Use low-energy light bulbs.
  4. Invest in a good quality building fabric.
  5. Choose an experienced SAP assessor who can offer useful recommendations on improving your SAP rating.
Key Factors Determining The Energy Rating of Existing English Houses Research has demonstrated that the most impactful factors on an existing building’s energy rating are:
  • The heating system’s efficiency;
  • The U-value of external walls; and
  • The geometry of the dwelling.
These factors account for up to 75% of the variance in energy ratings of buildings. Upgrading the building’s heating systems and addressing the U-value of walls by adding appropriate insulation, for instance, will improve dwellings energy efficiency and therefore their energy rating.

What is SAP and What Does it Mean For Your Building Project

A SAP rating is used to compare the performance between different homes in terms of energy efficiency. It indicates how much energy the dwelling will use, how much is lost or gained and how efficiently the building retains heat. The higher the rating, the more energy-efficient it is. That means lower fuel costs and lower carbon dioxide emissions. The SAP rating provides the basis for the Energy Performance Certificate, which gives a rating on a scale from A to G, depending on how energy-efficient the dwelling is. A SAP and EPC are requirements for any new home and any home being sold or leased out under part L of the Building Regulations. Without an EPC, Building Control will not sign off on a new-build, so it’s essential you comply with the framework. If you would like more information on the Standard Assessment Procedure (SAP) and how it affects your property, call Briary Energy for more information today. We are experienced experts in SAP evaluation for buildings of all types and sizes.  

SAP Calculations are carried out during two stages, where communication with the SAP assessor is key to gaining compliance:

Design stage – where you will need to make a submission to Building Control before any work begins Built stage – once the dwelling has been completed and established The two submissions of SAP Calculations are used by Building Control to check your compliance in accordance to the related targets. There must be evidence when it comes to your product specification – evidence that the design specification has been met. When you reach the ‘As Built’ stage of SAP Calculations, you will also need an EPC for the dwelling as well. Why not try our U-Value resource.