In July 2018 BEIS and BRE published SAP 10 which will be introduced when there is next a change to Building Regulations Part L in 2020. There are a number of changes which will impact the performance of new dwellings and also the level of information required.

Blewburton Ltd have access to Elmhurst Energy’s BETA version of the SAP 10 software. Using this software, we can help our client to predict how these changes will affect their ability to meet current Building Regulations and planning targets. Blewburton Ltd are ideally placed to help you prepare for the future by understanding these changes and determining the most cost-effective and appropriate strategies moving forward.

Some of the key changes to be aware of are:

  • Emissions Factors – If you install CHP you may need to look for alternatives. Now is the time to get to grips with heat pumps.
  • Lighting Energy – You will need to provide details of the proposed lighting.
  • Thermal Bridging – If you currently use ACD’s you will need to look for alternatives and have junction details modelled for accurate psi values.
  • Overheating Risk – If you are building near external sources of noise or security risks extra attention should be paid to risk of overheating.

These changes and some others are discussed in further detail below.

1. Fuel Prices

EPC bands are based on predicted running cost. Therefore, changes to costs will have an impact if you are targeting a specific EPC band.

Increases are seen in mains gas, wood logs and electricity, however reductions in cost are seen in bulk LPG and oil. Blewburton Ltd does not anticipate this having a major impact.

2. Emissions Factors

Most LPA targets are based on reduction in emissions, therefore, changes to emissions factors of fuels are expected to result in changes in proposed building services.

A significant reduction, of over 55%, in the emissions factor related to electricity is shown. This will result in electric heating looking much more efficient than it has previously. Heat pumps are expected to perform well but CHP, which offsets electricity demand, will no longer result in the large reductions it currently does. The draft London Plan already reflects these changes in the revised energy hierarchy,
and the GLA have been asking for reports to present reductions in both the current and proposed carbon factors since the beginning of 2019.

3. Heating Pattern

SAP works on a range of assumptions, whilst this may not reflect real life situations it allows buildings to be compared to each other.

Current and past version of SAP used different heating patterns for weekends and weekdays, however it has now been shown that there is less of a difference. To reflect this all days will now use the same heating pattern. Blewburton do not anticipate that this will have a major impact.

4. Lighting Energy

Lighting has previously been a very minor factor in SAP with little input required. In SAP 10 this will change. A reference lighting capacity will be calculated based on floor area and solar gain, if this is not reached the predicted light energy will increase. Whilst we do not anticipate this will have a major impact on results, power and efficacy of fixed light fittings will now be required, so additional information and evidence will be needed from design teams.

5. Thermal Bridging

Although not very common, in some SAPs we use a default y-value for thermal bridging, this value willbe increasing, we will therefore want to avoid using it as much as possible.

Accredited Construction Details (ACD’s) have been removed as they have been found to be inaccurate and not fit for purpose. It will now be necessary to model junction details for accurate psi values. If this isn’t done default figures must be used which will make meeting Building Regulations and planning conditions challenging.

6. Hot Water

To increase accuracy, calculations of hot water demand will now take into account the number of baths and showers. Electricity used by electric showers and shower flow rates will now also be accounted for. This is not expected to have a major impact on results, however there will need to be some additional information provided if Blewburton aren’t also doing your Part G water use calculations.

7. Photovoltaic Panels – New Technologies

Battery storage technology can now be accounted for when solar PV panels are used to generate electricity. A PV diverter, used to heat hot water via an immersion coil in a cylinder will also be able to be modelled in SAP 10. Blewburton Ltd anticipate that these technologies will become more and more popular with FIT’s ending, as the technologies improve and as electricity prices rise.

8. Photovoltaic Panels – Overshading

Currently overshading of PV panels is entered via 4 broad categories. In SAP 10 MCS overshading data should be used to increase accuracy. It is expected that all solar PV installations will have an MCS certificate and this should be provided as evidence.

9. Overheating Risk

Currently assessors can state that windows can be open in hot weather without any checks being carried out. In SAP 10 it will be necessary to indicate if there is a source of noise that would prevent windows being opened or if there is a security risk if windows are left open at night. If either of these areas are an issue (such as dwellings near a train line or a ground floor flat) then the software will assume that trickle vents only are used. Blewburton are increasingly seeing issues with dwellings (often single aspect flats with south facing windows) struggling to comply with Building Regulations in relation to overheating. This will increase the likelihood of problems and therefore clients are encouraged to be aware of the overheating risk. Blewburton should be consulted at an early stage to determine if there are likely to be overheating issues in relation to Building Regulations. It may also be beneficial to go beyond this and assess dwellings using TM59.

Blewburton Ltd’s support:

Using Elmhurst Energy’s BETA SAP 10 software we can model dwellings to determine how they will perform under SAP 10. This could be a dwelling recently completed, in construction or currently in the design stages. It could also be a hypothetical dwelling of a type that is typical for your company. If we are assessing dwellings for you under the current version of SAP they could be ideal for us to duplicate
in SAP 10.

Once the dwellings baseline performance has been established, we can model a range of changes to advise you of how best to comply with current Building Regulations and potential planning requirements. Whilst we don’t know what will be required under updated Building Regulations this will allow you to prepare for the changes to building specification that are likely to be required in the future. With a range of possible improvement measures you can take time to source the most cost effective and reliable solutions that work for your company.

Our top tips:

Calculate your thermal bridges now. Using default figures makes a huge impact so it is well worth calculating the psi values, and the earlier you do the longer you will have to make improvements.

Assess your risk of overheating, especially in blocks of flats. If a dwelling is shown as overheating there is a limited list of changes that can be modelled before active cooling needs to be considered. With the SAP 10 changes we are going to see more and more dwellings failing Building Regulations due to risk of overheating. Start looking at this in your standard unit types now to avoid problems further down the line.

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