
Outdated EPC ratings based on estimates can mislead you about your building’s true energy performance. As part of the upcoming RdSAP 10 methodology, Air Tightness data will be allowed to be input, providing more accurate and reliable EPC ratings. This blog explains how air tightness testing can significantly improve your building’s EPC rating and efficiency.
The Challenge: Unreliable Traditional EPCs
Currently EPCs relied on estimated air leakage values. These estimations often underestimated the actual amount of air leakage in existing buildings, resulting in inaccurate EPC ratings. This can have significant consequences.
Imagine a building owner who installs a less efficient heating system based on an inaccurate EPC that suggests good energy performance. In reality, due to high air leakage, the building might lose a significant amount of heat. This negates the benefits of the new system and can hinder sustainability goals.
Is Air tightness Testing the Solution for Accurate EPCs?
Air tightness testing is a non-destructive method for precisely measuring a building’s air leakage rate. It is done by pressurising the building interior slightly and measuring the rate at which air escapes.
The valuable data allows building owners or professionals to:
- Target Improvements: Identify and address weaknesses in the building envelope, leading to reduced air leakage.
- Make Informed Decisions: Gain a clear understanding of the building’s actual energy performance for informed choices regarding energy-saving measures.
- Enhance Value and Marketability: Demonstrate the effectiveness of improvements through better EPC ratings, potentially increasing the building’s value and marketability.
Air Tightness Testing in RdSAP 10
The updated RdSAP 10 methodology is due to be released on the 15th of June 2025 and will allow incorporating measured air tightness test results into EPCs, offering several benefits:
- More Accurate EPC Ratings: By incorporating measured air leakage data, EPCs become more reliable indicators of a building’s energy efficiency, providing valuable insights for stakeholders.
- Fairer Representation: Buildings with addressed air leakage issues will be recognised for their improvements, leading to fairer and more accurate EPC ratings.
- Incentivising Improvements: The ability to showcase the positive impact of air leakage reduction on EPC ratings motivates building owners and developers to invest in addressing these issues, promoting sustainable construction practices.
This means building professionals will be able to leverage the data from tightness tests to generate more accurate EPC ratings.

Improve Your EPC Rating with Air Tightness Testing
When you schedule an air tightness test with us, our comprehensive service provides the data you need to make informed decisions about your building’s energy performance. Here’s what you gain:
- Precise Air Leakage Assessment: Identify weaknesses in your building envelope that lead to wasted energy and potential discomfort.
- Actionable Insights: Gain a clear understanding of your building’s airtightness, empowering you to target improvements effectively.
- Unlock Efficiency Potential: Reduce air leakage and unlock significant energy savings throughout your building’s lifespan.
Beyond the Test: Optimising Your Building’s Performance
Air tightness test can be used to:
- Inform Energy-Saving Measures: Make data-driven decisions regarding targeted improvements like air sealing to optimise your building’s energy efficiency.
- Future EPC Assessments: Upon the release of Rd SAP 10, the air leakage data can be incorporated into future EPC assessments, potentially leading to a more accurate reflection of your building’s energy performance.
What’s Next?
By leveraging airtightness testing and the upcoming RdSAP 10 methodology, EPCs will soon provide a clearer picture of a building’s true energy performance. This allows for more informed decision-making, improved sustainability outcomes, and potentially greater cost savings throughout the building lifespan.
We offer a comprehensive range of air tightness testing services. Contact us today to discuss your specific needs and learn how we can help you improve your building’s EPC rating with air tightness testing.
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