Frequently Asked Questions
What is SAP and why do I need a SAP calculation?
Standard Assessment Procedure (SAP) calculations are a mandatory requirement for any new build dwelling. SAP is used to show compliance with Section 6 of the Building (Scotland) Regulations and is applied at the design stage of the build process.
SAP is the calculation methodology which determines the energy cost and carbon emissions generated to heat and light a dwelling.
What are Accredited Construction Details?
Accredited Construction Details (Scotland) deal with insulation continuity around the junctions of the build and the air tightness of the dwelling.
Accredited Construction Details (Scotland) can be downloaded from the BSD (Building Standards Division) website www.sbsa.gov.uk
Accredited Construction Details are not a mandatory requirement of Section 6 of the Building (Scotland) Regulations, however, they can significantly improve your DER (Dwelling Emission Rate) or BER (Building Emission Rate) and help you to achieve compliance
Why do I get a poor rating when my building is electrically heated?
Although electric heating is 100% efficient it is very expensive compared to other fuel types. SAP and SBEM are part based on the cost of heating the building, therefore, the more it costs to heat the building the worse your rating will be. The same theory applies to your DER (Dwelling Emission Rate) and BER (Building Emission Rate) figure. As before, your electric heating system is 100% efficient but you will produce a greater amount of CO2, thus having a negative effect on your DER or BER.
There are many choices available in terms of electric heating. However, there are various types of 'more efficient' electrical heating options in the market place such as:
- Heat pumps
- Low energy panel heaters
An alternative would be to use a renewable energy source such as:
- Photovoltaic cells
- Solar panels
Why does a heat pump produce a good DER or BER figure but produce such a poor SAP or SBEM rating?
A heat pump will produce a good DER or BER figure because the CO2 emissions from this system is very low, the SAP or SBEM rating on the other hand will be poor because:
- The initial cost of buying/installing the heat pump is higher than that of a gas fired boiler system.
- The heat pump has an electric back-up system and the cost of electric is high resulting in a poor SAP or SBEM outcome.
How does under floor heating affect my Dwelling Emission Rate?
If you are applying under floor heating to a screed or in a timber floor construction, this will have approximately the same DER compared to wet radiators.
If you are placing under floor heating within a concrete slab the DER will be poorer than that of a typical wet radiator system - this is due to the mass of the floor and it's resistance to react to changes in temperature.
How does mechanical ventilation with heat recovery affect my rating?
Surprisingly, your Dwelling Emission Rate (DER) will be higher when incorporating a Mechanical Ventilation Heat Recovery (MVHR) system into your building. This is due to the fact that the system requires a constant electrical demand which omits CO2 - this is reflected negatively in the rating.
The more accurate the information when supplied to Elmhurst regarding your chosen system, will in turn allow for a more accurate rating.
My Dwelling exceeds 150msq in gross floor area. Will I need to improve the standard of my heating system?
For any new dwelling exceeding 150msq it is recommended that the heating system should be zoned - refer to guidance in section 6 of the Domestic Handbook
