Passivhaus Potential

Location: Cork, Ireland

A group of residential buildings in a rural location are providing a warm and energy efficient living space, designed to meet the specifications of Passivhaus standard. These buildings consist of both the conversion of a stone-walled barn and new build, the development has used spray foam insulation to meet both airtightness and thermal insulation requirements throughout the structures.

The old barn building had solid stone walls: to get the required U-value 0.26W/m2K a 75mm layer of foam was sprayed directly onto the interior surface of the wall, forming a seamless finish that is not only airtight and watertight but is also thermally efficient. The spray foam layer was then covered with plasterboard for the interior finish.

The structures of the new builds, on the other hand, were constructed of two leaves of concrete blocks with a cavity held of 200 mm with insulating wall ties. This cavity was filled with spray foam. The result was a U-value of 0.12W/m2K.

The project designers Edge Architecture, wanted all the buildings to follow the design requirements of Passivhaus standards. This requires not only the highest airtightness standards but also extremely efficient thermal insulation. With the spray being applied, jointing between insulation on the walls and roof are a completely reliable method of ensuring airtightness as any detailing is easily accommodated. The buildings for this project had a target airtightness of 1m3/hr/m2 @ 50Pa