SAP Calculations for Extensions (Heatloss Assessments)
SAP Calculations (Heat Loss Assessments) are a useful way of demonstrating that highly glazed extensions, orangeries and garden rooms comply with the requirements of Part L1B of the Building Regulations via the Design Flexibility Criterion. This is something which is being requesting increasing more by Building Inspectors as a result of the growing trend for homeowners specifying bifold doors and roof lanterns within their extension projects.
Our highly experienced SAP Assessors have provided SAP calculations for thousands of highly glazed extension projects with varying degrees of construction complexity and site limitations over the years.
To date we have a 100% record in proving compliance with Part L1B of the Building Regulations. We are therefore confident that you will not need to compromise your design in order to meet the requirements of Building Regulations if you instruct us to undertake heat loss assessments on your proposed (or completed) extension project.
SAP Calculations for Heavily Glazed Extension - FAQs
How is compliance with Part L1B demonstrated?
Essentially two alternate extension SAP calculations are produced; the first is based on the existing property with a conventional extension of the same dimensions as the proposed works and a conventional level of glazing. This ‘Notional’ SAP calculation provides a calculated level of annual carbon dioxide emissions which in turn provides a target threshold for the proposed works.
A second ‘Actual’ SAP calculation is then prepared, based on the existing house and the specification of the proposed extension, sun room or conservatory. The calculated annual carbon dioxide emissions are then compared to the previously calculated target rate.
If the proposed extension carbon dioxide emissions are less than the target threshold, then the works are deemed to comply with Part L1B of the Building Regulations via the Design Flexibility Criterion without any additional requirements.
Conversely, if the proposed extension carbon dioxide emissions are greater than the calculated target threshold, then trade-off improvements will be required to either the extension specification or the existing house as a means offsetting the additional heat loss associated with the extra levels of glazing within the proposed extension above the standard threshold detailed within the Building Regulations.
Examples of commonly recommended improvements include additional depths of insulation to the extension floor or roof, improved glazing specificiations, top up loft insulation or cavity wall insulation to the existing property, or improvements to the existing heating system.
The SAP assessment for a conservatory or extension should ideally be completed as soon as the architect or contractor has finalised the proposed build specification for the extension works, since if the SAP calculations result in an initial compliance failure, it is far easier to recommend subtle amendments to specific insulation thicknesses or material amendments before any work has commenced.
When should the SAP Calculations be completed?
The SAP assessment for a conservatory or extension should ideally be completed as soon as the architect or contractor has finalised the proposed build specification for the extension works, since if the SAP calculations result in an initial compliance failure, it is far easier to recommend subtle amendments to specific insulation thicknesses or material amendments before any work has commenced.
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EPS Group have been providing cost effective, client focused solutions to the increasingly stringent requirements of local planning policies and the Building Regulations for more than 10 years. Whether you’re in the first stages of exploring exactly what your legal obligations are, or are facing a project delay as a direct result of energy compliance, we can help. We provide independent advice and fixed price quotations that arrive without obligation.
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