Despite the government’s push towards a net zero future, there remains a clear gap between the real-life energy consumption of many building products and that calculated by the Standard Assessment Procedure (SAP).
Here, Scott Conor, Chief Technical Officer at Trust Electric Heating, explores why the SAP and Reduced Data SAP (RdSAP) need to change – and fast – to stop building designers from missing out on product innovations that could improve the energy performance of new and refurbished homes.
There is so much talk about creating energy-efficient housing, and yet the system that supports its creation is lagging woefully behind the pace of innovation in the sector. This means that new technologies which could be supporting greener buildings are practically invisible to the people responsible for delivering them. So what’s wrong with the current system, and what needs to change?
Slow adoption of new technologies
One of the first major setbacks with the current SAP system is that it doesn’t reflect technological advancements within the industry.
SAP calculations are the only government-approved system for the calculation of energy ratings, and there’s no doubt that when they were first introduced, SAP and RdSAP were useful tools. However, in today’s more complex, ‘whole system’ approach to building design, there are a lot of technologies that are simply not catered for.
SAP guidelines are updated periodically to reflect changes to fuel prices, CO2 emissions, and primary energy factors. Innovation is evolving far faster than the SAP guidelines, and whilst updates to the most current SAP model consider construction materials, the thermal performance of building insulation, and the efficiency of heating systems, it doesn’t account for newer innovations in these areas.
So while companies such as ours are introducing new technologies to make heating systems more energy efficient and user-friendly for building owners and homeowners alike, SAP guidelines, especially for the RdSAP are not keeping up. As a result, building designers, specifiers, and those involved in improving energy performance within existing buildings aren’t being exposed to the most up-to-date technologies that could be used to create more energy-efficient homes.
The most recent SAP (SAP 10.2) was introduced in June 2022 with updated Part L building regulations and incorporated various changes to the methodology, including updated CO2 emissions, fuel prices, and primary energy factors.
For existing dwellings, the current version is RdSAP 2012, but this is expected to be updated later this year. For me, there is no question that RdSAP protocols need to be updated more often. When I look at how far our systems and smart controls have come in the last five years and see how they can now be successfully integrated with other products and technologies – such as smart hot water tanks and solar PV – I see huge opportunities to support the net-zero drive, if only the RdSAP could keep pace.
A lack of flexibility
The approved Product Characteristic Database (PCDB) is generally only reviewed in line with full SAP system upgrades, which is when new products and technologies are added. However, the approval process is long-winded – 18 months on average – and only covers the central technology.
So, for example, where we have an electric heating system that is part convection, part storage, and controlled by smart technology, it falls through the gaps and does not fall under the existing categories in a way that acknowledges its benefits. It cannot be added to the PCDB without going through a long and expensive process. This is just one example: so many new heating systems combine products and incorporate smart controls. Used intelligently, these systems can deliver vastly improved energy performance, but they are simply not catered for within the current SAP or RdSAP.
Out-of-date data
For new build properties, the SAP calculation analyses overall energy performance within a building to provide an overall EPC score. The RdSAP relies on assumptions and default values which have become outdated over time and misaligned with today’s building systems and technologies.
For example, bandings awarded to products in the SAP system feed through into Energy Performance Certificate ratings. When they were first introduced, the maximum SAP score was 100, but it is now possible for a building to score over 100, because – for example – it uses technology that generates surplus electricity. The current system doesn’t reflect this: another reason why, in my view, an overhaul is long overdue.
The limited scope of assessment
SAP calculations are based on standard assumptions, meaning they do not accurately capture the full complexity of energy usage within households. Indeed, they only consider regulated energy use.
Actual energy consumption is influenced by many factors, including human habits and behaviour. How occupants use energy within their homes, such as heating and cooling preferences, and energy-consuming activities such as cooking can greatly influence overall energy consumption. Household appliances can also impact energy performance with the frequent use of washing machines, kitchen appliances, or other energy-intensive appliances.
Post-Covid, with the introduction of flexible and hybrid working patterns we have seen a significant shift in occupancy behaviours with people being home more often. Naturally, this can lead to higher energy usage than that assumed by SAP. And when you factor in the current cost of living crisis and the rise in fuel poverty, we see countless examples of people heating only one or two rooms in their homes for some time to minimise the energy they use.
I believe that the current presumption, incorporated into the SAP calculations, is that controlling heating by separating it into two zones is better. This needs updating to reflect the way people are now using their homes. To obtain a more accurate representation of a building’s energy performance, the SAP needs to account for occupant behaviour and incorporate a broader range of factors into the assessment process to provide a more holistic view of building performance.
Lacking the capacity for complex buildings
Older buildings, including those classed as traditionally constructed, listed buildings and those in conservation areas, may be subject to exemptions and restrictions when it comes to energy efficiency improvement. They will also be subject to RdSAP guidelines, which rely on assumptions for anything that can’t be seen by an assessor.
Buildings like these often require an ‘out of the box’ solution, but if these solutions aren’t visible to architects and specifiers in the approved Product Characteristic Database, or as RdSAP generated suggested improvements, how can they be incorporated into housing improvement or refurbishment projects?
There is a lot of talk about updating SAP and RdSAP at government level, but if the building industry is to deliver on net zero housing targets, things need to move much faster. A failure to act fast will only delay the delivery of the energy performance solutions we need for new and existing homes now.
With revisions to the RdSAP anticipated later this year, I hope it aligns closer with industry innovation. I look forward to this with interest but maintain that more needs to be done in the meantime to get new and proven energy-efficient technologies and systems into the hands of architects and specifiers, and into finished buildings.