Given social and regulatory requirements and the drive to improve the energy efficiency of buildings, it is no surprise that experts and building contractors are looking for innovative and effective solutions. One of the key factors affecting convective heat loss is air permeability, which is one of the most common problems in the UK construction sector. AirGuard® Reflective film helps to provide an airtight insulation layer, effectively addressing this challenge.
When the architect and timber frame contractor for the Housing Association’s new build expressed a desire to minimize heating energy costs, DuPont offered an advanced material that was ideal for ensuring optimal airtightness in the construction. DuPont™ AirGuard® Reflective film is part of a range of innovative membrane and sealing solutions, the effectiveness of which has been confirmed by a BBA assessment of the product prototype. The metallised vapour barrier layer is impervious to air and moisture.
The York Housing Association implemented German Passivhaus principles in the construction of eight residential buildings in the Boundary Close area, with the project being partly funded by the Housing Corporation. The aim of the project was to create highly insulated and airtight structures with mechanical ventilation systems that allow the accumulation and reuse of ambient heat and solar energy. This system requires only one additional 2 kW panel heater in the living room.
“This concept is fundamentally different from the traditional UK approach, where homes are fitted with central heating systems and insulation materials are used solely to reduce heating costs. The materials used to ensure comfort have a high level of airtightness and insulation,” says Phil Bixby of Constructive Individuals. It was important to the housing association that tenants would respond positively to the new concept, that there would be no complaints, and that they would be able to maintain the ventilation system properly. A detailed survey showed that tenants were satisfied.
The structure of each house consists of lightweight wooden frame double beams with 8 × 300 mm thick wall panels and 4 × 400 mm thick roof panels filled with Warmcel insulation material. Solar collectors preheat hot water and fresh air supplied to the rooms.
DuPont™ AirGuard® Reflective insulation film was installed to ensure the continuous airtightness of the inner layer of the structure. Pressure tests showed excellent results:
- Roof edges: air permeability – 1.58 m³/h·m², air leakage – 1.51 h⁻¹
- Roof center: air permeability – 1.94 m³/h·m², air leakage – 1.86 h⁻¹
The L document approved by building standards specifies that the acceptable air permeability limit for the structure is 10 m³/h·m² at a pressure of 50 Pa. The values obtained during the tests are significantly lower than the permissible limit.
Nick Williams, Technical Manager at DuPont Building Innovations, notes: “The key factors in ensuring the airtightness of a structure are the quality of the membranes and tapes and the precision of the installation work. Our products are reliable and durable. Installation is simple, and when done correctly, they deliver maximum efficiency. The amount of energy saved also depends on the knowledge, experience, and maintenance of the end user.”