In the quest to build more energy-efficient homes, a groundbreaking study has shed light on a significant oversight in how we measure air leakage. The findings, published in the journal Buildings & Cities, challenge the conventional wisdom surrounding fan pressurisation tests (FPTs) and could reshape how we approach energy efficiency and ventilation in residential buildings.
At the heart of this research is David Glew, a senior lecturer at the Leeds Sustainability Institute, Leeds Beckett University. Glew and his team conducted 37 pressurisation and co-pressurisation tests on attached homes across the UK. Their goal? To quantify the inter-dwelling air exchanges that occur during FPTs, a method commonly used to measure air leakage in homes.
The results were eye-opening. On average, 21% of the air leakage measured by FPTs was found to be inter-dwelling, meaning it was exchanged between neighboring homes rather than escaping to the outside. This revelation suggests that homes are more airtight than FPTs indicate, a crucial factor when assessing energy efficiency and ventilation performance thresholds.
“Homes are more airtight than we thought,” Glew explained. “This means that using FPT results to inform energy models and building regulations could lead to under-ventilation and misclassification of homes deemed suitable for natural ventilation.”
The implications for the energy sector are substantial. For instance, using the FPT result to replace default values for airtightness in energy models used to create Energy Performance Certificates (EPCs) for 11 of the case study homes improved their energy efficiency rating (EER). This modest improvement represented a 5% reduction in predicted annual carbon emissions, an 8% reduction in space heating demand, and a 3% reduction in fuel bills.
But why does this matter? Well, accurate airtightness measurements are fundamental to energy efficiency and ventilation requirements. If FPTs are overpredicting air leakage due to inter-dwelling air exchanges, it could affect the accuracy of these tests in attached homes. This, in turn, could impact building regulation compliance, ventilation decisions, and energy models.
Glew’s research, published in the journal Buildings & Cities, which translates to Buildings & Cities in English, has sparked a conversation about the need for further knowledge, industry guidance, and protocols for inter-dwelling air exchange during FPTs. The study calls for a reevaluation of current practices and standards, particularly for different house types, forms, and constructions.
As the construction industry continues to evolve, this research could shape future developments in energy efficiency and ventilation. It serves as a reminder that even the most established methods can benefit from scrutiny and innovation. After all, the path to a more sustainable future is paved with continuous learning and adaptation.