31st July 2020

How to pass a SAP Assessment

If you are looking to build any type of dwelling, then you will need SAP calculations. SAP calculations help you to work out the amount of energy your property is likely to use, and also the level of CO2 emissions it will produce. They are a requirement of the Building Regulations for all newly built dwellings in the UK. This has been a requirement for all new homes under Part L of the building regulations since 1995, so it is something that most developers are familiar with. 

What are SAP calculations and why are they important?

SAP stands for ‘Standard Assessment Procedure’ and is the only government-approved system for determining a new home’s energy rating. The scale for a SAP calculation runs from 1 to 100, with 100 representing no energy costs at all! The calculation works by showing the higher a dwelling’s SAP rating, the lower the fuel bills and the lower the CO2 emissions.

The role of SAP calculations for buildings is threefold:

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

No one is legally allowed to let or market a property for sale unless the relevant builder can demonstrate that they conform with SAP calculations. SAP calculations are an essential element in the design of any residential scheme, so if you are a first time builder it is important to get your head around the process and understand how it works. 

What do I need to pass a SAP assessment?

In order to ‘pass’ the SAP assessment, a builder must quantify the heat retention and solar gain properties of the dwellings. You must also demonstrate the dwelling’s construction quality while showing evidence of the commissioning of systems. Finally, the dwellings predicted CO2 emissions must be predicted. There are some things you can do to make you more likely to pass your SAP assessment. Keep reading for some tips to help you pass your SAP assessment. 

Get your SAP calculation completed at the design stage

Ideally you want to get your SAP calculation completed at the design stage, and definitely before you start any work on your site. Part L targets change regularly, so you don’t want to have to make changes to your development once you have already started the work and then find out too late you’re failing the SAP assessments. Having your assessment done in the design stage means you can plan your design to the specifications of the SAP assessment. 

Use low energy light bulbs

A quick and easy way to make a significant improvement on the SAP is to use low energy light bulbs. Technology in the lighting sector has moved on incredible amounts in recent years. Gone are the days where they were ugly and awkward to fit, they are now really straightforward and a great replacement to typical lighting fixtures. Ensure every light bulb in the dwelling is low energy (LEDs or fluorescent tubes) and avoid old fashioned tungsten or halogen lamps.

Use an accredited assessor

As regulations are constantly evolving, you want to make sure that the assessor you choose to use is completely up to date with the current regulations. You don’t want to go with somebody who is unsure and isn’t fully aware of the importance of getting your SAP assessment right. You might initially save a bit of money on a cheaper assessment but this could end up costing you thousands of pounds in the future if you are given poor advice. Briary Energy offer professional SAP calculations, with extensive knowledge of all current building regulations.

Improve the building fabric

For most dwellings, heat loss through the fabric accounts for the largest amount of heat loss. Lowering U-Values by increasing the insulation in the property will overall enhance the thermal performance and help with your SAP assessment. It is possible to achieve compliance with Part L without the need for renewable technology if you can reduce your U-Values with the right fabric.

Insulate party walls

To achieve best results in your SAP assessment, party walls (walls used by two properties) must be fully insulated and appropriately sealed to avoid any potential heat escaping between properties. This is particularly important in mid-terrace houses and apartments. You will be penalised on your SAP calculations if you build with partially insulated party walls, and uninsulated party walls are not allowed. 

Consider renewable energy

If you are struggling to get over the line to pass your SAP assessment, renewable energy could be the best option for you. Energy created from solar panels (photovoltaic), solar thermal (solar water heating), wind turbines or even hydro power can be incorporated into the SAP assessment. These options can sometimes be expensive to install, so do your research before committing to anything on your assessment. 

Thermal bridging is important

Thermal bridging is the heat loss that leaks out through the areas where external walls meet. As a minimum, developers should be following the generic Accredited Construction Details (ACD) guidelines, which allows for an improved psi value to be used in your SAP calculations. Using bespoke psi values for all or some connections can be a very cost effective way of improving thermal performance and will help achieve a low air pressure test.

If you are looking for an accredited company to perform your SAP assessment, or just want some more information about the process, get in touch with us.

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28th July 2020

Air Permeability Building Regulation Advice From A Test Engineer

When you design or construct a new residential dwelling, it’s energy consumption is. Air leaks can reduce the energy efficiency of a building as it may require more energy to heat and as a result increase the dwelling’s carbon footprint. 

Air permeability testing is done to verify the robustness of a property’s building materials and workmanship, and that wok have been done to reduce uncomfortable drafts and 

Air permeability testing is also a key component of SAP Assessments, which are used to determine the energy performance of a residential building. Air leakage tests are also applicable for commercial buildings, which follow SBEM Calculations.

Here are 12 pieces of advice for the best results of controlling air leaking from one of our senior engineers, Marc.

Decide from the get-go how you are going to deal with air tightness

“Set early targets. And make sure all stakeholder tradesmen take part in a pre-start toolbox talk. Everyone involved needs to be aware that the plan is to create an airtight building.”

“Ensure that all necessary SAP calculations have been made and that all results have been accurately recorded for every property tested. You can find this number on the SAP report (under, q50, DAP, or Air Permeability).”

You may find it helpful to mark out an airtight barrier early on. Draw a line connecting all areas which separate heated elements from unheated elements. As an additional control measure, why not appoint a single focal point on all air tightness issues for concerned parties”.

Carry out regular inspections throughout the building program

“To counter the effects of shoddy workmanship, consider installing an inspection schedule during construc-tion. You will want to avoid test failures at all costs since these lead inevitably to costly remedial work.”

One common source of leakage happens when cavity walls are breached at the time of construction – commonly in the vicinity of floor joists. Be sure to use industry-standard fixings to prevent this”.

Take care with dry lining

“Plasterboard put in place with the dot-and-dab method can prove problematic. Undetected leakage in brick or block may leave an unwanted path from board to floor slab. Two solutions spring to mind. The first is to initially parge-coat the wall. The other is to lay continuous lines of adhesive round board sides, and socket cut-outs.”

Seal all pipework to prevent air leakage

“Be sure to seal all waste and supply pipework at the exact places where it passes through floors or walls. Use approved, gunned sealants (for bigger gaps use pre-compressed strips of foam, which are flexible and expandable. Avoid foam — it shrinks too readily, breaking the seal. There are flexible foams on the market, specifically tested for use in airtight projects”.

Doors and windows

“As an expert in the field, I see plenty of door and window frames that have been incorrectly sealed. Save yourself a lot of heartaches —always use suitable seals and sealants to avoid gaps wherever they are located.”

Radiator pipework

“Underfloor manifolds or radiator pipes aren’t always sealed when the floor is screeded. This problem is often compounded by covered gaps with flooring. Also, radiator pipes often pierce walls behind a radiator. This is a very difficult area to access and check.”

Make sure you include eaves, loft hatches, and cupboards

“In homes which include roof space rooms, it is common to find air leaks at the eaves, around cupboard doors, and in loft hatches. Such rooms are often added later, effectively partitioning unheated space from living space proper, so it’s best to seal these as efficiently as any external door or window”.

Pay particular attention with light fittings

“Take care to properly fit all light switches and fittings, electrical appliances and plug sockets before being tested, since temporary sealing of these components is prohibited. Improper fitting runs the risk of air loss leading to poor results.”

Seals around services

“All modern homes are serviced. So be aware that pipework for water, drainage, and gas; flues servicing boilers, and areas housing electric cables commonly leak – we regularly come across leakages in meter boxes”.


Bathrooms offer the perfect opportunity for air leakage. The main culprits are bath panels and pipework. Ensure that all avenues for air leakage are adequately sealed before attaching bath panels, covers for vani-ty units, extractors, and anywhere that requires boxing-in.

Skirting boards must be sealed

For optimum efficiency, seal all skirting boards top and bottom, with silicone sealant. You should not rely on traditional carpets or other floorings to stop air leakage.


For best effect, ensure that kitchens are finished. This includes all appliances, any required boxing-in, and the full installation of extractors. It is no surprise that in common with bathrooms, leakage in kitchens is often detected where there is pipework. Don’t forget the cavities behind kitchen cupboards!

At Briary Energy, we provide fast and effective air permeability testing services for new builds that can contribute towards your development’s SAP calculations. Our fully qualified experts will guide you through air leakage testing and help identify improvements for your development.

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