SAP Calculations & EPCs (no vat)

SAP Calculations and EPCs for new builds, extensions and conversions


What is SAP Calculations


A SAP rating is the calculation that is required in order to produce a Predicted Energy Assessment and an On Construction Energy Performance Certificate.

Building Regulations require that a SAP calculation and a Predicted EPC is submitted for new dwellings prior to the commencement of work.

A SAP calculation indicates a score from 1 to 100+ for the annual energy cost based on:

  • The elements of structure

  • The heating and hot water system

  • The internal lighting

  • The renewable technologies used in the home


The higher the score the lower the running costs, with 100 representing zero energy cost. Dwellings with a rating in excess of 100 are net exporters of energy.

SAP calculations allow comparison to be made of the energy running costs of dwellings anywhere in the UK. This is achieved because the calculations are predominantly location independent and are based upon a notional standard occupancy that overcomes variations associated with physical location and the differing ways in which people utilise their homes.

A SAP calculation for a new dwellings is a desktop exercise, the client or their designer submits drawings, plans and specifications of the development to the assessor. It is recommended that the SAP calculation is undertaken early in the design process, this will help to prevent any costly redesign of the dwelling.

SAP calculations usually involve 4 stages:

Design - draft stage

From the plans and drawings provided by the designer, the assessor prepares summary numerical information which includes the total floor area of the dwelling; the floor area of the lounge or living room; the areas of the heat loss floors, heat loss walls and heat loss roofs; dimensions of external windows and doors; storey heights and so on.

From the specification provided the assessor calculates the performance of the thermal elements. These are expressed as 'U' values (the rate at which heat passes through the fabric of the building), the higher the 'U' value the greater the rate of heat loss. The assessor then inputs this data into the SAP calculation. Data is entered relating to:

  • Type of dwelling

  • Floors

  • Walls

  • Roofs

  • Openings (windows, doors, roof lights)

  • Ventilation

  • Main and secondary space heating

  • Hot water generation

  • Renewable technologies, including photovoltaic panels and solar water heating

  • Energy efficient lighting


The software determines whether the proposed dwelling will comply with the requirements of the Building Regulations with regards to the conservation of fuel and power. The assessor is able to use the software to model different variations of the design if the initial specification doesn't show compliance. The assessor should then advise the designer of the shortfalls and recommend solutions as required.


Design - final stage

The client, designer and the assessor agree the finalised version of the design, this may involve amendments to the initial design in order to achieve SAP compliance. Data from the finalised design is input into the computer program.

From this the assessor produces reports that the client or designer need to submit to Building Control, this will include a Predicted Energy Assessment (this provides a rating of energy performance based upon the specified design).


Built - draft stage

For the majority of new dwellings an air pressure test will normally be required (for small sites of 2 dwellings or less an air leakage value of 15 m3/(h.m2) may be used in the calculation and no test is required). The client or designer provides the results of the air pressure test (if required) to the assessor and also advise of any variations from the specification.

The assessor will edit the SAP calculation to reflect the results of the air pressure test and any variations to the specification. The software is used to check that the completed dwelling still meets the requirements of the Building Regulations with regards to the conservation of fuel and power. If it does not the assessor recommends remedial action.

For new build dwellings the assessor checks to ensure that the dwelling is registered on the Government's central database register of national property addresses. If it is not the assessor arranges for the address record to be created.


Built - final stage

The assessor finalises the SAP calculation and creates the Energy Performance Certificate (this provides a rating of energy performance based upon the dwelling as built). The EPC must, by law, be displayed in a new dwelling put up for sale on the open market.

In addition there are other documents that are required by Building Control such as the SAP worksheet report and the SAP data input report.

The assessor provides the client with the Energy Performance Certificate and SAP Calculations.

Building Regulations require that an Energy Performance Certificate is provided prior to a completion certificate being issued.

SAP New Build for new build houses and flats

SAP Calculations is required in order to produce a Predicted Energy Assessment required by the law to be compliant with Part L of the Building Regulations prior to the commencement of work.

Please email us at hello@manchesterepc.com or call 07872314115 to discuss further.

What we need from you:
  • Site plan
  • Floorplans, sections and elevations
  • Constrcution specification for walls, floors and roofs
  • Window specfication
  • Primary & secondary heating system
  • Renewables details (if any)
We will deliver:
  • Documents required for complaint with the Building Regulations
  • Unlimited support to ensure to make you compliant
  • U value calculations for submission to Building Control
  • 2-3 working days turnaround

SAP Conversions / Change of Use for conversions / change of use

EPC is required in order to be compliant with Part L of the Building Regulations if you have changed the use of building such as from commercial to flats or from a house into multiple flats. .
Please email us at hello@manchesterepc.com or call 07872314115 to discuss further.

What we need from you:
  • Site plan
  • Floorplans, sections and elevations
  • Constrcution specification for walls, floors and roofs
  • Window specfication
  • Primary & secondary heating system
  • Renewables details (if any)
We will deliver:
  • Documents required for complaint with the Building Regulations
  • Unlimited support to ensure to make you compliant
  • U value calculations for submission to Building Control
  • 2-3 working days turnaround

SAP Extensions Extensions with glazing > 25%

SAP Calculations is required in order to be compliant with Part L of the Building Regulations when you do an extension that is over 25% area of the existing floor area.
Please email us at hello@manchesterepc.com or call 07872314115 to discuss further.

What we need from you:
  • Site plan
  • Floorplans, sections and elevations
  • Constrcution specification for walls, floors and roofs
  • Window specfication
  • Primary & secondary heating system
  • Renewables details (if any)
We will deliver:
  • Documents required for complaint with the Building Regulations
  • Unlimited support to ensure to make you compliant
  • U value calculations for submission to Building Control
  • 2-3 working days turnaround











Energy Performance Certificate Services


Energy Performance Certificates

Energy Performance Certificate (EPC) is required by law when a building is built, sold or put up for rent. If you are a landlord or homeowner and need to provide an Energy Performance Certificate (EPC) this will need to be completed by an accredited domestic energy assessor. They will carry out the assessment and produce the certificate. Energy Performance Certificates (EPCs) give information on how to make your home more energy efficient and reduce carbon dioxide emissions.

What does the EPC say about the property?

An Energy Performance Certificate gives clear information about the energy performance of a property. An EPC will also make recommendations about how the property could improve it’s energy performance.

How long does it take to perform an EPC assessment?

An assessment takes anywhere from 25 minutes to 1 hour for a domestic EPC and a couple of hours to a couple of days for a Commercial EPC depending upon the size of the commercial property. Factors such as the size of the property, it’s age and general access to it, will have an influence on the time. Generally, an energy assessment won’t cause much inconvenience but, it’s important that the energy assessor can get access to any loft space and heating appliances (e.g. a boiler). An internal and external inspection of the property is also required for a certificate.



What is an energy assessor looking for?

  • Noting the construction of the walls and checking wall insulation.
  • Confirming how many windows are double glazed.
  • Counting the number of open fireplaces.
  • Checking the make and model of the boiler under EU SEDBUK regulations.
  • Looking for green energy devices such as solar panels.
  • Counting the number of low energy light bulbs.
  • Confirming the type of heating system used e.g. gas, electric, underfloor etc.
  • Noting down the type of material used to insulate any hot water cylinders.
  • Assessing the heat loss through roof, check loft insulation.
  • Checking for excessive window area in larger houses.
  • Taking precise measurements of conservatories and extensions.
  • Counting how many habitable rooms are heated.
  • What is the procedure once the assessor has visited?

    Once the assessor has visited property, the information is uploaded onto the Government authorized software. A certificate is produced and emailed to the customer within 24 hours after the payment is received.