How to achieve the best result in your SAP calculation
05 Apr 2016
SAP Calculations are an element of the Part L building regulations for new build residential buildings. It is required to create the energy performance certificate (EPC) that is needed to sell the property. Our team know what you need to do to get the SAP Calculation pass you need.
1. Use an accredited assessor
With ever evolving regulations, you need to make sure that the assessor you are using is up to date with the current regulations, and is aware of how they impact your build costs. A few pounds saved on a ‘cheap SAP’ could mean thousands of pounds spent due to poor advice.
2. Get your SAP calculation completed at the design stage
The SAP Calculation should ideally be completed at design stage, and certainly before you start work on site. With Part L targets regularly changing, you do not want to have to make retrospective changes to your new development if you find out too late that they are failing the SAP assessments.
3. Fabric first – invest in good building fabric
It is possible to achieve compliance with Part L 2013 without the need for renewable technology if you can reduce your fabric U values. A good base for your U-Values is to refer to the Model Design. Ideally you should be looking to improve on these values whenever possible. The Target Fabric Energy Efficiency means that you need to focus on a good building fabric before considering bolt-ons like PV panels.
4. Consider ways to lower the thermal mass
A low thermal mass (e.g. timber frame) means that the heating system does not have to heat the building fabric as much. This means that it will be easier to achieve a ‘Pass’ for your SAP.
5. Don’t shy away from renewables
If you are struggling to get over the line, don’t shy away from the idea of waste water heat recovery, photovoltaic panels or wood burning stoves. These options can be easier and cheaper to install than alternative options for passing the SAP calculation.
6. Insulate party walls
For best results in SAP, party walls should be fully insulated and suitably sealed to avoid heat escaping between dwellings. This is especially important in mid-terrace houses and apartments. Your SAP Calculations are penalised if you build with partially insulated party walls and uninsulated party walls are not allowed.
7. Enhance you heating controls
Using heating controls such as Weather Compensators and twin zone control, will reduce the DER, which means that it will be easier to achieve a SAP pass.
8. Use low energy light bulbs
Technology in the lighting sector has moved on in leaps and bounds in recent years. Energy saving bulbs are no longer ugly or awkward to fit and don’t take ten minutes to warm up. Ensure every light bulb in the dwelling is low energy (LEDs or fluorescent tubes). Avoid old fashioned tungsten or halogen lamps. This is a quick, cheap change which makes a significant improvement on the SAP.
9. Don’t settle for the confidence factor when building multiple dwellings to the same specification
When building multiple dwellings to the same specification you have the option to spot test rather than test all dwellings for air permeability. If you take this option, you may save on air test costs but any dwelling that is not air tested at ‘As Built stage’ will be subject to what is called a ‘confidence factor’. This means a figure of 2 is added to the average air test result on site and this figure is then used in the SAP. If your Site Managers are confident of achieving a low result, and your build schedule allows, it could be worth air testing every dwelling to avoid incurring the penalty of the confidence factor.
10. Have psi-values calculated when building multiple dwellings to the same specification
If you are regularly building to the same building specification, we recommend you have psi-values for each of the main thermal bridging junctions calculated. By not investing in these calculations, it is likely you will be spending money elsewhere to ensure your buildings meet the mandatory Target Emission Rate and Target Fabric Energy Efficiency scores.
Would you like to know more?
An Energist SAP includes expert advice and a 48 hour fast-track service. We are not just a company that inputs your details and leaves you with a problem if it doesn’t ‘pass’. We advise. We consult. We advise some more. And we always bring our considerable experience to help you to save money on your build. Let us take the hassle out of your SAP calculations today.