It’s important to note that until the final document is published – which we expect to be sometime this summer – we only have the government response to the SAP consultation to guide us as to what this may look like. Following this, a consultation on changes to Part L itself can be expected towards the end of the year, which may introduce further and potentially more wide-ranging changes to be adopted in 2019.

At this stage, it appears there will be a number of minor technical amendments to SAP, as well as some more substantial changes which could have an impact on your current strategy for Part L1A 2013 compliance.

Some of these changes are likely to bring improvements in assessed performance, however the majority may make it more challenging to achieve compliance;

• Changes to carbon emissions factors, the most significant of which is a reduction in the emissions from electricity of around 23%, to reflect progress that has been made in decarbonising the National Grid. This is likely to make electric heating systems more viable, however conversely would reduce the benefit from PV systems currently used to meet carbon reduction targets, leading to larger systems being required.
• Changes to the assessment of thermal bridging, to remove the use of the ‘approved’ values associated with using Accredited Construction Details (ACDs) and worsen the default values. For many clients, we already mitigate this impact through ensuring that all your main building junctions are thermally modelled. We can calculate these on a one-off basis, or build a full library based on your standard detailing to use on future projects.
• A more accurate assessment of hot water consumption would require us to account for the energy consumption and emissions from electric showers – which are overlooked in the current methodology – as well as more accurately reflect the design flow rates.