Air tightness measurements in older Danish single-family houses

This paper reports and discusses the air tightness of the building envelope in existing single-family houses in Denmark. The air tightness of the building envelope depends in particular on the performance of specific construction details. There is a lack of knowledge about the air tightness of the building envelope of older buildings despite the fact that the air tightness has a major influence on the energy use. In connection with renovation of the Danish building stock, the coming years will see increased focus on the air tightness of the building envelope like in other countries.
This paper presents the results of measurements in 16 single-family houses built between 1880 and 2007. The air tightness of the building envelope was measured according to EN ISO 9972 using the blower-door technique. The results are compared with measurement results of the average air-change rate in the same houses measured over a period of 1-3 weeks when the houses were in normal use.
The measurement results of the air tightness of the building envelope range from 1.1 to 5.8 l/(s·m²) at 50 Pa. The investigated houses are all naturally ventilated. The results of the ventilation measurements showed an outdoor air supply ranging from 0.09 to 0.28 l/(s·m²) per heated floor area, which is below the requirement stipulated in the Danish Building Regulations of 0.3 l/(s·m²).
Typically, leaks are observed in connection with penetrations of the envelope, e.g. for electrical installations, exhaust ducts and chimneys. In addition, leaks are observed around older windows and doors and in connection with wooden ceilings and attic hatches. The findings should be taken into account when renovating older single-family houses.