By Luke Smith, managing director of Build Test Solutions

EPCs only predict the thermal performance of a building correctly in 44% of cases, according to new research.

Conducted by Build Test Solutions and the Energy Saving Trust, on behalf of the Department for Energy Security and Net Zero (DESNZ), the research argues that EPC calculations are based on assumptions rather than real data, leading to misleading results.

“The problem is that people rely almost entirely on visual methods when surveying homes,” says Luke Smith, managing director of Build Test Solutions.

“Most EPC ratings are determined in this way, with an assumed level of performance calculated. But visual methods can only go so far in determining the presence and effectiveness of insulation. We shouldn’t be relying on this method to accurately represent the true thermal performance of our homes.”

The current situation

No matter the skill or experience level of the assessor or surveyor, the true extent of air leakage or thermal bridging cannot be determined visually. This can result in ineffective solutions being installed.

The disconnect between fuel poverty and EPC ratings supports this claim. While a social housing property might look to be in a good state of repair, it is what is underneath that causes thermal performance issues. The result is a social housing property that is hard to heat, greatly impacting residents’ costs and their living conditions.

To eradicate fuel poverty and deliver carbon neutrality, properties must be affordable to run and have minimal environmental impact over their operational lifecycle. Without tailored and accurate building performance knowledge, this will be challenging to achieve.

Building quality signoff

The success of a multimillion-pound social housing project investment is often based on regulatory sign-off, improved EPC ratings and positive resident satisfaction survey responses. These survey methods, while offering some benchmarking, are highly subjective and anecdotal.

Specific and proactively measured insights are often overlooked or at best simply seen as a checkbox requirement for compliance. This is partly down to a misconception that the measurements are difficult and expensive to obtain. It is also due to a lack of understanding about how measurements relate to strategic objectives, such as reducing CO2 emissions, lowering fuel bills and tackling fuel poverty.

Social housing providers must proactively seek to invest in their housing stock and create better living conditions for their residents. The best way to do this whilst ensuring that they are acting in their occupiers’ best interests is to be led by a robust understanding of housing stock performance beyond basic EPC ratings.

The future of EPC

Luke explained: “EPCs are imperfect yardsticks that change with time. Instead, reliable, quantifiable data is needed to verify the true impact of spend. More specific measurements should be the future of EPC ratings.

“We need more SMART objectives that are based on directly measurable parameters that can be linked directly to the headline strategic objectives of the business.”

Luke outlines potential areas of measurement, including: Heat loss (W/K); mould risk (0-100); overheating risk (0-100); airtightness (m3h/m2); air quality (CO2, PPM, VOCs); and U-values (W/m2K).

Pre works testing

Changes to EPC standards could also better encourage pre and post-retrofit testing of social housing properties to measure the baseline thermal performance level.

By having a provable measure rather than an assumed performance level, social housing providers can use data to compare properties and assign funding to the homes or rooms in greatest need. Better measurement would highlight the problem areas of each property and allow providers to invest in the most impactful retrofit solutions first, rather than having a blanket approach across properties.

Post works testing

Encouraging testing after retrofit through an EPC scheme would allow accurate data comparison between the tests carried out before work was done. This comparison will evidence the true value delivered by the investment committed by social housing providers.

The financial strains on social housing providers force them to re-evaluate their priorities and retrofit investments constantly. Rather than relying solely on resident satisfaction surveys, housing providers can validate the delivered outcomes and prove a project has met the desired goals. Without data-based testing and validation that directly quantifies success, investments could be reduced, and residents could suffer.

“By carrying out thermal performance measurements and air leakage tests, people can take a “right-first-time” approach to retrofit,” added Luke. “The housing provider can use data to directly determine the most cost-effective retrofit solutions that offer the best return on investment while making the most impact on tenant’s lives.”

New builds should also be assessed against the design intent to prove if it has met the intended thermal performance specifications. With such data fed back into EPCs, it could allow housebuilders to easily spot any thermal performance issues and sort them out before residents flag them as issues once they are living in the property.

Supporting technology

The measurement solutions that will allow the housebuilding and retrofit industry to stop making EPC assumptions already exist.

With the increased adoption of IoT, smart thermostats and other internet-connected appliances that can share useful performance data from buildings, getting this information is becoming much easier. This data can help drive tools like SmartHTC and Mould Risk Indicator to provide powerful insights into the overall performance of the building fabric and the effectiveness of the ventilation.

Measurement solutions are also on the market that help assess air permeability, like Build Test Solutions’ Pulse. This can be used to better understand energy performance and background ventilation rates, all while properties are occupied. This allows the cost of heating a property to be understood and problem areas to be identified.

U-value measurement technology, like Heat3D, can also be used to get an accurate understanding of heat flow and U-values across a whole surface. This can show where insulation has failed or where additional insulation is needed to ensure insulation is only added to areas that need it.

Utilising these technologies will help create more accurate, reliable and effective EPC ratings, driving an informed approach to building improvement and retrofit.

Learn more about BTS’ measurement system on the website