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SAP 2016 Consultation Launched

SAP2016 Consultation Launched

  • Have your say on the future of SAP calculations

  • Nineteen changes are being considered

  • Electric heating, PV batteries and shower use among items under review.


If you’ve ever wanted to have a say about SAP calculations, now’s your chance!

After months of anticipation, a public consultation is now open to gauge our views about the next version of SAP, which is used to calculate EPC ratings and Target Emission Rates.

Called ‘SAP2016’, this is the first indication that a revised Part L isn’t too far away – historically, the SAP methodology has always been updated just before a new release of Part L. This is prompting speculation about how much of a cut we’ll see in the next Target Emission Rate as the Government slowly but surely moves us towards building to a zero carbon standard.

But that’s at least 18 months down the line… this first step gives architects, builders and developers a chance to voice their opinions about how we calculate emission rates for buildings in the UK.

The consultation document, which is open until the 27th January 2017, sets out twenty questions which, depending on public feedback, may be written into the next version of SAP.

You can download your copy of the document from this link:

Remember:SAP doesn’t set out Target Emission Rates – that’s covered by Building Regulations – but it does set out how emission rates are calculated.

Here’s what we think are the ten biggest proposals for new buildings in this proposal:

  1. Electric heating has always performed poorly in SAP. This is because the UK has been heavily reliant on coal power stations, which creates high levels of CO2. But in the last few years we’ve seen a dramatic shift away from coal. Gas, solar and wind are filling the gaps in our energy supply which means our electricity supply is greener than ever before. It’s proposed that SAP reflects this by cutting the emission factor by a quarter. Electricity would still have a higher emission factor than gas or oil, but would mean that panel heaters and heat pumps would achieve a lower DER than currently. On the flip side, if the emission factor is reduced, PV panels would have less of an impact in SAP.

  2. In terms of district and community heating systems, research shows that SAP ‘significantly underestimates’ the distribution heat losses. New calculations are being proposed to make SAP more accurate, but in many cases this could raise the DER of dwellings using district heating networks.

  3. SAP currently works out how much energy is needed for hot water based on the size of the house only. It’s proposed that SAP should be clever enough to know how many baths and showers a dwelling has, and whether it uses power showers or not. From this information, it can make better assumptions about how much energy is needed to heat water in the home.

  4. Tests have shown that System 3 decentralised ventilation systems typically don’t perform as well in real life as they do in SAP. There’s a proposal to make the efficiencies worse in SAP to correct this – it could see developers moving back to standard intermittent fans in some cases.

  5. Three new technologies technology combinations are being considered for the new SAP. PVs which feed excess electricity into batteries, PVs which feed excess electricity into an immersion cylinder, and solar thermal panels which feed excess hot water into the dwelling’s heating system.

  6. While on PV, it’s proposed that changes are made to the overshading factor in SAP. This could make PV perform 15% worse in the design calculations compared to the current methodology. At the As Built stage, the SAP would be updated with data from the MCS (Microgeneration Certificate Scheme) – this is considered to be more site specific, and would therefore make SAP more accurate.

  7. There are several proposals up for discussion in terms of calculating thermal bridges. If you want to avoid all thermal bridges, the default y-value could raise from 0.15 to 0.20. This almost certainly would cause a fail under the Target Fabric Energy Efficiency in England. You can still use approved thermal bridging packs (such as Accredited Construction Details) or have your own psi-values commissioned.

  8. The summer overheating section is being reviewed – this flags up when a dwelling is expected to have a high temperature risk in summer months. There have been calls for SAP to be much smarter in this area. We’re unlikely to see dynamic modelling become a feature of SAP, but the proposal is to make the current calculation a bit cleverer.

  9. The way SAP treats lighting is under review. Currently, it works out assumed energy use of lighting based on how many bulbs are low energy. The suggestion is to change this, and instead count up the total wattage of all lights in the dwelling. So the more energy efficient your light bulbs are, the better it will perform in SAP.

  10. SAP is twenty years old, and since day one it has always assumed the same in terms of heating our homes. We heat our living room to 21 degrees, and the rest of the house to 18 degrees. We have our heating on for nine hours a weekday, and 16 hours a weekend day. Is this still relevant?

After the consultation closes, all feedback will be taken on board, and a new SAP methodology will be published – probably in the middle of 2017.

This new SAP will include some of the proposals above, but are likely to go through some changes before the final version is agreed.

From there, we’d expect Part L to be updated, which is likely to include an update to the Target Emission Rate. No timeframes have been put in place for this to happen just yet, but we’re reasonably confident that we’ll still be working to the current version of Part L this time next year.


Jon Ponting

Author: Jon Ponting

This article was published by Jon Ponting on 18.11.2016.