Energy Performance Certificates for Commercial & Domestic Buildings

Assess Ltd

Tel        0121 453 8332

Mob     07771 662 357

Email   [email protected]

SAP for Conversions (created / change of use)

New domestic dwellings (created by change / change of use) will require a SAP Assessment to Building Regulations part L1B and a SAP EPC which you will need to  supply to  your Building Control Office so that he can issue you with your completion certificate. These must be produced by an accredited On Construction Energy Assessor (SAP Assessor). 

(complete our SAP Questionniare)


We will check your compliance with building regulations at both design and as-built stages and assuming there are no issues provide your U-value & SAP Reports in addition to your lodged SAP EPC at completion.

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Building Regulations Part L1B require the new fabric elements of your extension (walls, floor, roof, windows, doors) to achieve at least the minimum u-values specified within tables 1,2 & 3 in addition to the overall Dwelling Emission Rate (DER) being no greater than than the DER of a theoretical version of the property built to current building regulations.


Tables 1, 2 and 3 of Building Regulations Part L1B indicate the minimum u-values (thermal effciency) allowed for your new walls, floor, roof, windows and doors (building fabrics), these must be achieved.

We will provide u-value calculations (and advice if necessary) for each of your fabric elements as required by Building Control.



Once your building has been 'modelled' within our (SAP) software we will produce SAP Reports indicating the DER and TER (Target Emissions Rate) for your building, we require the DER to be no higher than the TER. Should this not be the case we will make specific recommendations on how this could be acheived, you can chose to install these improvements or find your own solutions.


We can provide all the documentation that will be required by Planning and Building Control and offer EARLY ADVICE and SPECIFIC RECOMMENDATIONS on any potential non compliance issues so please get in touch as soon as possible.

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In addition to calculating the U-Values for the Fabric of the dwelling we need to consider the efficiency of the HVAC services (Heating, Ventilation & Air Conditioning) and can offer you practical advice in ensuring that these contribute to the overall ratings rather than purely meeting minimum requirements.

Best advice to ensure a compliant and speedy SAP ASSESSMENT


Fill in our SAP Questionnaire THOROUGHLY ... Most delays are caused because of missing information that we need to complete your assessment. Everything we need (pretty much) is requested on our SAP Questionnaire so completing it thoroughly will certainly save time (naturally no need to repeat information already contained on your drawings and specifications).


BE SPECIFIC ... concerning your fabric constructions, we need to understand the type and thickness of each material that you have used and specific insulation types (eg - 'Celotex GA4000' not just 'Celotex')


CONTACT US EARLY ... so we can advise you of potential compliance issues before they become expensive re-works.

It's not only CHANGE OF USE that require SAP Assessment you will also require a SAP EPC for NEW BUILD HOMES, HIGHLY GLAZED EXTENSIONS, Barn CONVERSIONS, COMMERCIAL to DOMESTIC conversions and SINGLE to MULTIPLE dwellings (flats & appartments).


Existing Domestic EPC's and Commercial EPC's are produced using software that relies on many 'assumed' values (RdSAP & SBEM) however there are instances when calculated U-Values can give a far more accurate and representitive calculation for the property.


ONLY SAP ASSESSORS  /  On Construction DEA's

are qualified to produce U-Value calculations.


EPC Assess are quaified and accredited :-


On Construction Domestic Energy Assessors ( OCDEA / SAP ASSESSORS )

Non Domestic Energy Assessors ( NDEA / Commercial Assessors )

Domestic Energy Assessors ( DEA )

Green Deal Assessors - Domestic & Commercial ( GDA / NDGDA )


... so can provide Energy Performance Certificates for (virtually) ANY PROPERTY TYPE and have years of experience working with architects, designers, builders, contractors large and small on thousands of standard and not-so-standard developments across the UK. We are happy to share our knowledge and do what we can to ensure your projects easily acheives compliance however EARLY INVOLVEMENT is CRITICAL if we are to guide you in the most cost effective way.

Opening like windows & doors generally lose more energy than the surrounding building fabric however glazing can provide useful Solar Gains that can be used to compensate for the losses providing they do not cause summer overheating, we can ensure that an optimum balance is achieved to ensure compliance.

It's never too early to get us involved and we are happy to be as involved as you would like us to be and hope our experience a cross a range of building types will allow us to be of service no matter what your next project entails.




  ... so we can help you with what you have planned for tomorrow !


Please contact us on the form below and let us know more about your project, you can attach drawings if you would like specific advice or information and we'll be happy to call you back at your convenience :-


In order to achieve compliance with Building Regulations Part L1B there are two seperate 'targets' to acheive, individual U-value targets for each of your fabric elements and an overall Dwelling Emission Rate target (DER). 


Minimum Fabric U-value are clearly stated in tables 1, 2 and 3 of Building Regulations Part L1B, these are minimum values for walls, floor, roof, windows and doors, these must be achieved and we produce U value Calculations to varify this.

(SAP U-value calculations are only valid if produced by an accredited SAP Assessor you cannot rely upon calculations produced by any other means)


Dwelling Emisson Rate (DER/TER) the DER  (Dwelling Emission Rate) is the measure of the overall CO2 emissons created by your building. It cannot be worst (higher) than the TER (Target Emission Rate) which is based upon the same buiding acheiving building regulations. There are many factors which affect these values such as your fabric u-values and heating efficiency.


We will provide all the documentation that you require for Building Control and liase directly with your BCO to ensure that Part L1B is achieved and he has the information required to issue your completion certificate promptly and without fuss. We will advise you of any potential complaince issues and provide specific options that you can consider to ensure L1B compliance.

However the earlier you contact us within your project the more help we can be in terms of ensuring that you will be compliant while you are still in a position, if need be, to make cost effective changes early.



SCALED DRAWINGS including floor-plans, elevations, sections and site layout for the entire building (new extension and existing building).


HEATING/COOLING specifications of space and water heating systems, ventillation and any low-carbon technologies (LZC), including any new systems that you are going to install as part of your extension project).


CONSTRUCTION SPECIFICATIONS for your new fabric elements - walls, floors, roof, windows and doors. The fabrics of your existing building will be calculated using standardised thermal efficiencies based on its age (or other documentation that can be provided). 


We may also send you our SAP QUESTIONNAIRE to collect any outstanding information that we require (you can send these documents to us electronically or in printed format).


It is important that you provide as much information as possible otherwise we are required to use DEFAULT inputs which tend to be 'worse case scenario' and can contribute to issues of non compliance.


Once we have collected all of your information we will 'model' your data within our software and initially produce a Part L1B Checklist and U-value Calculations to ensure that your building is compliant with the appropriate Building Regulations and calculate a DER for the 'proposed' building.


If compliant we can produce your U-value and SAP Reports in addition to your Pre or Lodged EPC. However if  there are any areas of non compliance we will provide specific recommendations that you can consider in order to rectify this.


Your final SAP EPC can only be lodged at completion and if it is compliant with Building Regulations Part L.

Service and Documents Provided


Design Stage SAP & U-value Reports in addition to an L1B compliance check to ensure the building will be compliant at completion.


Specific recommendations concerning any compliance issues.


Build Stage SAP & U-value Reports in addition to an L1B compliance check to ensure the building is compliant at completion.


Lodged SAP Energy Perfomance Certificate (EPC)


SAP EPC & Reports

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