A Standard Assessment Procedure, or ‘SAP’ as it is commonly referred to, is a UK government-recommended methodology for measuring the energy rating of a residential dwelling.

Using advanced software, it calculates typical annual energy costs for water heating, internal lighting and space, and a rating from 1-100+ is issued.

In order for new dwellings to comply with Part L1a and Part L1b, SAP 2012 has been used as the basis for checking such dwellings. Once a dwelling is complete, an Energy Performance Certificate (EPC) is produced. This post aims to give you some top tips for passing a SAP Calculation.

SAP calculations ebook | Sustain quality

SAP Calculation – The Earlier The Better

We recommend getting a calculation done as early on in the design process as possible. The earlier a SAP calculation is carried out, the more options you will have to demonstrate compliance with building regulations. Additionally, it can prove to be costly to improve a specification once work on-site has begun.

Low Energy Lighting

For a new build, the minimum requirement is that 75% of internal lights are low energy. By fitting all low energy internal lights will help you are increasing your chances of passing an SAP assessment.

Improve The Fabric

Did you know that heat loss through fabric accounts for the largest amount of heat loss for most dwellings? Do improve heat loss, we suggest lowering u-valves by increasing the amount of insulation, enhancing thermal performance.

Install High Thermal Performance Windows

Nowadays, you can obtain windows with u-valves as low as 1.0. A BFRC certified window can offer considerable heating improvements.

Air Pressure Test

A more airtight dwelling, the better it performs thermally. Most builders can achieve a rate of 5m3/hm2, but consider carrying out pressure testing, too. These can offer advice on how to build an airtight dwelling effectively.

Thermal Bridging

We recommend using bespoke psi values for all or some junctions as they can be a cost-effective way of improving thermal performance, helping you achieve a low air pressure test.

Developers should follow the generic ACD guidance. This allows for an improved psi value to be used in the SAP calculation. However, there are a variety of bespoke psi values which are calculated by manufacturers of building products, trade bodies, retailers etc.

Heating Controls

As standard, most properties with require the following as a minimum:

  • Programmer
  • Thermostat
  • Thermostatic radiator valves

Larger properties – over a floor area greater than 150m2 – will require a time and temperature zone control. However, you can involve advanced controls. These could be a delayed start thermostat or a weather/load compensator – both of which offer a significant benefit.


A waster water heat recovery system extracts heat from shower or bath water after it goes down the plug hole. This heat is then transferred to fresh water, helping to raise the temperature of the water, prior to heating. In a similar way, flue gas heat recovery systems extract heat from flue gases to pre-heat the water entering the boiler.


Solar panels, solar water heating, wind turbines and even hydro power can be incorporated into the SAP assessment.

How Can Sustain Quality Help You?

We hope you found this post useful. If you would like to find out more about our SAP calculation services or would like to speak to one of our team members about energy advice for your property, get in touch on 01372 438 039 or fill out the form below and we’d be more than happy to help.

Have you read any of our other blogs on SAP calculations? Click the links below:

SAP calculations ebook | Sustain quality

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About Us

We are a friendly team of Engineers delivering Sustainability and Building Compliance Solutions for developments in the Commercial and Residential sectors, which include Energy Statements, Noise Impact and Vibration Assessments, BREEAM Assessments, and Air Quality Assessments in the Environmental, Social and Governance sectors.

Contact us at:

Sustain Quality Ltd

PO Box 393


KT11 3EL


01372 438039