Domestic On-Construction Calculations, Assessments and Energy Performance Certificates

All new dwellings now require an Energy Performance Certificate (EPC) upon completion.  However, the process is different to that used for existing buildings.  Commonly called Standard Assessment Procedure (SAP) or occasionally Building Regulations United Kingdom Part L (BRUKL) calculations, you should be working with your accredited energy assessor throughout your project to ensure you meet the Building Control requirements.  You don't want any nasty surprises at the end!

Whatever type of property you have, we can help provide the on-construction calculations you need.  Our fully accredited assessors are experienced in dealing with all types and sizes of projects from small flats  to large carbon neutral off-grid developments.  We also deal with conversions, changes of use and mixed use complexes.  Our team are used to working with other professionals including project architects to help keep your project smoothly on track.  Additionally, if you are still at the planning stage, we can provide the reports and support necessary to help you obtain the permissions you need.

To discuss your residential project please contact our team now.

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Actual prices depend on size and complexity of your project.  Contact us for a free no obligation quotation.

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Frequently Asked Questions

Domestic On-Construction

England
Scotland
Wales
Northern Ireland
England

There is currently no requirement to display a Domestic Energy Performance Certificate (EPC) within a dwelling in England.  However, doing so may be beneficial, particularly in rental properties where it could be affixed to the building in a boiler or meter cupboard.

In the case of marketing a newly constructed dwelling, care should be taken to ensure that all EPC requirements are met.  Displaying the Energy Performance Certificate in the home communicates the information required to prospective buyers.

Scotland

It is a requirement under law in Scotland that the Energy Performance Certificate (EPC) must be ‘affixed’ to the building. Building standards guidance suggests that the EPC be located in the boiler or meter cupboard. A copy should be retained with other legal papers relating to your property.

Wales

There is currently no requirement to display a Domestic Energy Performance Certificate (EPC) within a dwelling in England.  However, doing so may be beneficial, particularly in rental properties where it could be affixed to the building in a boiler or meter cupboard.

In the case of marketing a newly constructed dwelling, care should be taken to ensure that all EPC requirements are met.  Displaying the Energy Performance Certificate in the home communicates the information required to prospective buyers.

Northern Ireland

There is currently no requirement to display a Domestic Energy Performance Certificate (EPC) within a dwelling in England.  However, doing so may be beneficial, particularly in rental properties where it could be affixed to the building in a boiler or meter cupboard.

In the case of marketing a newly constructed dwelling, care should be taken to ensure that all EPC requirements are met.  Displaying the Energy Performance Certificate in the home communicates the information required to prospective buyers.

Energy Performance Certificates (EPCs) are currently valid for up to ten years throughout the UK.  However, some schemes reduce this period significantly so more frequent assessments are required.

It can also be an advantage to the building’s owner to have a more recent assessment.  This is particularly true where energy efficiency improvements have been carried out that are not reflected in the current certificate.  Where buildings are tenanted, it can also make life easier for a landlord if assessments are renewed at strategic points within the tenancy cycle.

Standard Assessment Procedure (SAP) calculations are produced using a computer model.  They do not require the assessor to visit the site of the building.  As a result it is important that accurate and reliable information is submitted to the assessor.

The exact information required will vary from project to project and your assessor will discuss this with you.  However, the following items are typically required:

  • The full postal address of the building.  This must include the correct postcode as confirmed by Royal Mail.
  • A site plan including the orientation of the dwelling(s).
  • Scaled plans of each storey of the building (normally at 1:100).
  • Elevation drawings for each elevation.
  • Sectional drawings of the dwelling.
  • Details of the principal heating and hot water system.  This needs to include the make and model of boiler, details of heating emitters (e.g. radiators), hot water cylinder size (if applicable) and the system controls.
  • Details of any secondary heating system present.
  • Details of any cooling system present.
  • Details of ventilation systems and/or extractor fans.
  • Details of the internal and external lighting.
  • Details of the construction of all the different floors to the property.  This needs to include the type and thicknesses of insulation and any other building products used.
  • Details of the construction of all the different external walls to the property.  This needs to include the type and thicknesses of insulation and other building products used.
  • Details of the construction of all the different roofs to the property.  This needs to include the type and thicknesses of insulation and other building products used.
  • Details of all the doors and windows.  This needs to include the sizes, type of frame, type of glazing, thickness of glazing and any low emissivity applications (coatings) used.  A full window schedule including U-values for each unit (not just the glass) is the best way to achieve this.  Window schedules are usually readily available from window suppliers.
  • Details of any renewable technologies (renewables) installed in the building.  These could include ground source heat pumps, air source heat pumps, solar water heating, photovoltaics (PV), wind turbines and/or hydrokinetic technologies.
  • Details of any heat recovery systems installed.

If you are in the process of designing your building, the assessment will help you decide the minimum standards for each system to ensure that your finished building meets the required energy performance standards.

Standard Assessment Procedure (SAP) calculations are used as part of the Building Regulation requirements.  They establish that new dwellings meet the minimum requirements established for energy performance and efficiency.  A SAP calculation produces a Predicted Energy Assessment and ultimately an On-Construction Energy Performance Certificate for a new domestic building.

Approved Document L1A establishes the requirements in England for new dwellings in terms of energy performance.  Similar documents exist for the devolved administrations of Scotland, Wales and Northern Ireland.  Additionally, local authorities can also have their own requirements in addition to these which they maintain through their Planning and Permitted Development systems.

Whilst there are some key differences between all these requirements, the core methodologies remain similar.  The documents establish minimum standards for each element and system to ensure that they are efficient both in terms of energy and carbon emissions.  However, these are minimum standards.  Each administration requires that the home overall exceeds these minimums to meet standards for carbon emissions, energy efficiency and primary energy use.

The Standard Assessment Procedure (SAP) provides these values based on:

  • The elements of structure;
  • The internal lighting;
  • The heating;
  • The hot water system;
  • Any renewable technologies installed in the home.

In terms of Energy Performance, a rating based on expected energy costs is used.  This is the same as that seen on the Energy Performance Certificate (EPC).  The higher the score, the lower the running costs.  On this scale 100 represents zero energy cost.  Dwellings with a rating in excess of 100 are net exporters of energy.

The rating produced by a SAP calculation is largely location independent.  It is also based on a notional occupancy to overcome the different ways in which people use their homes.  As a result, SAP calculations allow the energy running costs of dwellings anywhere in the UK to be compared.

During construction it may be necessary to make some amendments to the design.  Keeping your assessor informed during this process, seeking their advice prior to confirming any changes, will help to ensure that your finished building will comply with the current regulations.

Once construction is complete an air pressure test (sometimes called an air tightness test or air leakage test) may be required.  This test confirms the air tightness of the finished building to ensure it is energy efficient.  You will need to provide a copy of the certificate to your energy assessor.  If an air pressure test is not required by law you may still wish to obtain one.  If the result of a test is not available then the assessor will use a default value in the SAP calculations.  This value is a worst case reflecting a very poor standard.  Having a test conducted voluntarily is likely to improve your final rating and help demonstrate that you have complied with the regulations.

During this stage the assessor will edit the SAP calculation to reflect the results of the air pressure test and any variations to the specification.  The approved 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 for any reason the building does not meet the required standards, the assessor can advise remedial action to get your project back on track.

The assessor will also check to ensure that any new building is registered on the Government’s central database register of national property addresses.

If you have included renewables as part of your project, you assessor will also require final confirmation of these.  They will also need copies of any final installation certificates like the MCS certificate for new solar arrays connected to the electricity grid.

At this point your Building Control Officer will confirm that they are satisfied the specification provided and the final calculations reflect the building accurately.  Your accredited assessor will then create the Energy Performance Certificate (EPC).  The EPC provides a rating of energy performance based upon the dwelling as it has been built.  Often this is different from the design calculation as it reflects changes that have been made during the construction process.   Once lodged on the National Register, the final Energy Performance Certificate (EPC) must, by law, be displayed in the new dwelling if it is 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.  Your assessor will provide all of these documents to you to pass on to your Building Control Officer.  Without these you should not be able to get the building signed off and obtain your Completion Certificate. The exact process here depends upon the location of your building and the Building Control organisation you are using.  Our expert assessors and your Building Control Officer will both assist you as much as they can to ensure this process is completed as smoothly as possible.

The accredited energy assessor uses the plans, drawings and specifications you provide to prepare summary information for the dwelling.  This includes calculating 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; the dimensions of external windows and doors; and storey heights etc.

If your architect has not already done so, your assessor will then calculate the performance of the thermal elements (walls, roof, floor etc).  These are expressed as U-valuesU-values express the rate at which heat passes through the fabric of the building.  The higher the U-value, the greater the rate of heat loss and therefore the worse the energy performance of the element.

Your assessor will then input all this data into the approved software and produce 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;
  • Internal 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.

Rarely, the initial draft and specification will pass the assessment by meeting all the requirements.  Normally the assessor will need to work with you and your design team to model different variations of the design until a version is developed that meets all the requirements.  The assessor can advise the designer of the shortfalls and suggest possible solutions as required.

This is why it is so important to involve an accredited energy assessor as early as possible in the design process.  Having to make changes after construction has taken place can be both expensive and time consuming.  All to often we are only approached at the end of construction which causes unnecessary stress and expense.  As more local authorities are enforcing their own requirements, it is becoming more and more common for some of this work to be completed prior to an application for Planning Permission being submitted.

By the end of this stage, your energy assessor can provide you with the reports that you need to submit to Building Control for them to advise you during the construction phase.  This will include a Predicted Energy Assessment which provides a rating of energy performance based upon the specified design.

WARNING:  This is often where things start to go wrong!  Our experienced assessors know that in the real world changes during the construction phase are almost inevitable.  Changes occur due to a wide range of reasons which may include discoveries on site, supply issues, budgeting measures or even special offers from suppliers.  However, you must remember changes from the agreed design are likely to result in changes to the performance of the building.  Please, keep in contact with your assessor during the building works and discuss changes with them before you commit to them.  They can check to make sure your final building will still meet the requirements and won’t require expensive remedial works.

Exemptions

England
Scotland
Wales
Northern Ireland
England

Currently, exemptions are in place for dwellings in England that are:

  • temporary buildings that will be used for less than 2 years
  • stand-alone buildings with total useful floor space of less than 50m²
  • some buildings that are due to be demolished where the planning process for this has already been completed
  • properties being let that are holiday accommodation and rented out for less than 4 months a year
  • properties being let (not sold) under a licence to occupy instead of a tenancy
  • some Listed Buildings in specific circumstances – you should get advice from your local authority conservation officer if the work would alter the building’s character.  More information is available here.
  • residential buildings intended to be used less than 4 months a year

Scotland

Exemptions are currently in place for dwellings in Scotland that are:

  • temporary buildings with a planned time of use of two years or less.

Wales

Currently, exemptions are in place for dwellings in Wales that are:

  • temporary buildings that will be used for less than 2 years
  • stand-alone buildings with total useful floor space of less than 50m²
  • some buildings that are due to be demolished where the planning process for this has already been completed
  • properties being let that are holiday accommodation and rented out for less than 4 months a year
  • properties being let (not sold) under a licence to occupy instead of a tenancy
  • some Listed Buildings in specific circumstances – you should get advice from your local authority conservation officer if the work would alter the building’s character.  More information is available here.
  • residential buildings intended to be used less than 4 months a year

Northern Ireland

Exemptions are currently in place for dwellings in Northern Ireland that are:

  • temporary buildings with a planned time of use of two years or less

 

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