SAP Calculations

SAP Calculations Overheating Calculations SBEM Calculations Energy Statements Energy Performance Certificate (EPC) Sound Insulation Testing Water Efficiency Calculations Ventilation Testing and Commissioning Air Tightness Testing Asbestos Surveys Fire Risk Assessment Planning Application
SAP Calculations Overheating Calculations SBEM Calculations Energy Statements Energy Performance Certificate (EPC) Sound Insulation Testing Water Efficiency Calculations Ventilation Testing and Commissioning Air Tightness Testing Asbestos Surveys Fire Risk Assessment Planning Application

What Are SAP Calculations?

SAP calculations are required to comply with the Approved Document L of the  Building Regulations.  SAP calculations come in two formats; L1A (new builds) and L1B (extensions and conversions).

How your SAP calculations are carried out will depend on whether your project is a new build, or an extension or conversion.

SAP Calculations for New Builds

For new builds, your SAP calculations will be divided into two reports: ‘Design Stage’ and ‘As Built’.

Design Stage Report:

  • Before construction begins, our team will assess and approve the construction details of the property.
  • This data is input into calculation software in order to produce TER and TFEE rates and to demonstrate that the building is DER and DFEE compliant.
  • A ‘predicted energy assessment’ is produced.

As Built Report

  • Once the building is complete, the construction details are re-assessed and any final details included, such as boiler model or air tightness score.
  • This final report produced the EPC.

SAP Calculations for Conversions

SAP Calculations for extensions and conversions are divided into ‘Notional’ and ‘Proposed’.

Notional Report

  • Our team will assess the construction details of the entire property, plus the proposed extension or conversion. From this, they will create a report with benchmarked data.
  • To create the report, the construction detail data is input into SAP calculations software in order to produce notional TER and TFEE rates and DER and DFEE measurements.

Proposed Report

  • The proposed report will use the benchmarked data for existing elements. For any new or upgraded elements, our team will assess the actual performance data.
  • This data is then input into SAP calculations software in order to produce the proposed TER and TFEE rates and DER and DFEE measurements.
  • The performance values of the proposed elements must be lower than the benchmarked standards in order for the property to pass.
  • In addition to this, the overall DER and DFEE measurements must be lower in the proposed report than in the notional report.
  • If the building’s SAP calculations demonstrate that the building’s performance values are all lower in the proposed report than the notional report, a new EPC is produced, replacing the property’s existing EPC.

SAP Calculations for Over-Glazed Extensions

Part L1b of the Building regulations requires that areas of new glazing should account for no more than 25% of new floor area. Nowadays  many extension modern designs will propose more than this, and therefore will not comply with this rule.

However, you can eliminate the negative effect of extra glazing in a highly glazed extension by upgrading other elements of the construction or showing additional solar gains from this extra glass.

There are two main options available for achieving compliance with Part L1B.

Area Weighted U-Value Method

Paragraph 4.5 of Part L1B, allows for the use of the area weighted U-Value method where glazing is in excess of the 25% limit. Under this method the overall area-weighted U-value of the extensions constructions and glazing should be better than that of a Notional Extension, of the same size and shape, that complies with the standards set out within the Reference Method defined in Part L1B.

This method does not need to involve an assessment of the whole property. It is best done at design stage, where levels of insulation and glazing types can still be tweaked to achieve a compliant result.

Where the existing dwelling is opened up to the extension, it is often the case that the area weighted calculation does not provide a compliant result – but all is not lost. The Whole Dwelling Calculation method can build on the work done to construct a more complex argument for compliance.

The Whole Dwelling Calculations Method

The final and most complex way of demonstrating an extensions compliance to Building Control is by carrying out a Whole Dwelling Calculation.

Under the Whole Dwelling Calculation method, SAP 2012 software is used to carry out a comparative SAP Calculation. The carbon emissions of the dwelling with the proposed extension will be compared to the carbon emissions of the dwelling with a Notional extension that complies with the standards under the Reference Method. Provided the emissions are lower with the proposed extension, it would comply with Building Regulations.

This method needs a survey of the existing property so that an energy model for the whole building can be produced. It takes more time but is often needed where the area weighted method does not provide a compliant result.

Compensating Measures

If the whole dwelling calculation method still doesn’t provide a compliant result, all is not lost! It is possible to specify some compensating measures to offset the effect of the extension. Examples range from very simple and low cost (Extra Loft Insulation) to more complex and higher cost (new more efficient boiler or new windows). We will always work with you to help you to achieve compliance for the lowest possible cost.

Need help with SAP Calculations pass?

At CAMSONS we can help you to achieve compliance by offering a variety of solutions to suit your design. We understand that in many cases, keeping your costs down is important so we offer affordable and efficient solutions to your insulation and energy needs by using tried and tested methods of meeting the requirements of approved document L while maintaining its modern look. Please Call 0333 577 5020 or email at info@camsons.co.uk.