Revision to Section 6 (Energy) of the Building Standards

Industry News / September 11 2020

SAP

Although not formally announced, we understand that revisions to Section 6 (Energy) of the Building Standards are now programmed for October 2021, with a consultation taking place towards the end of the year.

The main change will be to introduce the new energy calculation software known as SAP10 in lieu of SAP2012. In terms of other Section 6 (Energy) changes, we anticipate that Aspect Gold Level 1 will become the minimum standard for compliance. There could also be a reduction in the maximum permissible U-value for fabric elements which has been consistently reduced through previous revisions.

We also understand that there is no plan to amend Section 7 (Sustainability), therefore there will be no big changes under that section of the Building Standards, apart from Aspect 1 (Carbon Emissions) that may be impacted by the Section 6 (Energy) changes.

Below is a summary of the SAP10 changes and their likely impact:

Fuel Prices & CO2 Factors

EPC bands are based on predicted running costs. Changes to the fuel price rates in SAP10 will impact on predicted running costs and effect the EPC band achieved. The changes see an increase in the fuel price of mains gas and electricity, but a reduction in the cost of LPG and oil. We don’t anticipate these changes having a major impact on results.

SAP 10 will see the CO2 emissions factor of electricity reduced from 0.519 kgCO2/kWh to 0.233 kgCO2/kWh. This is due to the increase influence of renewable energy technologies that produce electricity for the national grid. This means that electric heating will be much more efficient than before, with heat pumps expected take over from fossil fuel burning systems. Below is a table outlining the changes between SAP2012 and SAP10.

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Heating Pattern

SAP 10 will introduce a different heating pattern, which will see all days of the week having the same heating pattern. In SAP2012 the heating was on more at the weekend and less during the week on the assumption that people were at home more, however studies have shown that there is no significant difference in the amount of heat used between week days and weekends. This should make for a slight improvement in the energy rating of homes as the heating will be on less within the calculations.

Lighting Energy

Lighting has previously been a fairly minor factor in SAP, with little input required. SAP10 will calculate a ‘reference lighting capacity’ based on the dwellings floor area and solar gains. Should this capacity not be reached, or be exceeded, the predicted lighting energy will be increased as a result. This will result in additional data entry being required in within the SAP Calculation for each dwelling. Power and efficacy of fixed light fittings will now need to be added to the SAP Calculations. Default efficacy figures will be provided for where the information on light fittings cannot be obtained. Whilst we do not anticipate this having a major impact on results, additional information is required, which will increase the take-off time associated with each assessment.

Thermal Bridging

The new regulations are anticipated to encourage more accurate assessment of Psi-values based on the proposed construction rather than reliance on Accredited Construction Details. In tandem with this, the ‘default’ Psi-values will be increased in order to discourage their use within SAP Calculations.

Hot Water Demand

To increase the accuracy of SAP Calculations, calculation of the hot water demand will be required in SAP10. This will require the number of showers and baths to be quantified. Electricity used by showers and the flow rate of showers will also now need to be added. This is likely to lead to an increase in the amount of energy used by a dwelling when compared against SAP2012.

Photovoltaic Panels

SAP 10 will now be able to accommodate the specification of battery storage technology, which will benefit the dwelling if installed. You will also be able to divert PV energy directly to the immersion coil in a hot water cylinder through the use of a PV diverter giving a benefit in SAP10 if specified.

SAP2012 currently only has four broad categories for overshading of PV panels. SAP10 will now allow entry of MCS overshading data. The MCS procedure for assessing near and far field objects will provide more accurate assessment of overshading and will be the preferred method of assessment where an MCS certificate is available.

Finally in SAP2012, blocks of flats could have PV supplied to a landlord’s supply via a single inverter, allowing the individual flats to claim the CO2 saving from the electricity generated. In SAP10 this will no longer be allowed. Only dwellings with their own inverters will be able to benefit from the cost (£) and CO2 savings associated with PV. This is likely to result in developers seeking alternative solutions for cost (£) and CO2 savings on blocks of flats.

Overheating Risk

SAP10 will require assessors to more accurately assess the potential for leaving windows open during hot weather. In SAP10, if natural ventilation is used to combat overheating, assessors will be required to indicate if there is a source of noise that prevents the windows being left open, and also if there is a security risk where windows are left open at night. If either of the answers to these questions is ‘yes’, ‘trickle vents only’ will be assumed for the window opening extent and the associated air change rate used in the assessment. This will increase the likelihood of problems with overheating in dwellings, which may only be overcome by controlled ventilation such as MVHR or CMEV, or changes to the extent of south facing glazing , or the introduction of solar shading to limit heat gain in summer.

Thermal Mass Parameter

SAP10 will no longer allow the selection of indicative low, medium or high options for calculating the thermal mass parameter. This means that all dwellings will now need to have their thermal mass parameter calculated based on their individual element areas and associated kappa values. Whilst we do not anticipate this having a major impact on results, additional information is required, which will increase the take off time associated with each assessment.

As it stands, it will be very difficult to assess the actual impact on SAP Calculations until such times as we have access to the Scottish version of the new SAP10 software, which we hope will be in advance of the new regulations being adopted. It is however obvious that more time will be required in order to process the SAP Calculations for each dwelling under SAP10. 

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