Airtightness Measurements of Wood Frame Low Energy Row Houses

Airtightness is a key component of energy efficient buildings. The blower door method can be used to quantify the airtightness. The requirements for airtightness in Norway have become stricter. This leads to a growing interest for airtight constructions and methods.

Jåtten Øst in Stavanger is a development of low-energy row houses. There are a total of 73 apartments with 3 different types of configurations. The row houses were planned to have an air change rate at 50 Pa, n50 lower than 1.0 h-1. None of the craftsmen involved had previous experience in building low-energy houses with specific airtightness requirements. Common materials and constructions for timber-frame buildings were used.

The airtightness of all the apartments was measured. Pressurization and depressurization tests were carried out both when the wind-barrier was finished and before takeover. The air change rate at 50 Pa pressure difference, n50 varied between 0.70 and 1.63 after finishing the wind-barrier, and between 0.48 and 1.29 before takeover.

The results demonstrate that skilled craftsmen without specific training or experience in airtight building were able to produce dwellings with n50 better than 1.0 h-1 with common materials. Improved airtightness beyond the national required level of n50 <2.5 h-1 is thus an achievable and probably cost-efficient way of reducing energy demand. Polyurethane-based expanding foam was used more extensively than in typical projects.