Abstract
Deep renovation of the existing building mass is an important task to reach the target of energy efficient buildings and neighbourhood. However, the current renovation rate is only 1% of the European building stock each year, and barrier for increased rate must be addressed. Attaching prefabricated elements with integrated technologies such as photovoltaic panels or ventilation equipment to the façades and roofs can improve energy performance and indoor climate as well as provide local renewable energy supply. The construction period can be short, with limited disturbance to building usage. The project 4RinEU has developed and demonstrated solutions suitable for several climates. Building airtightness of the renovated buildings is an important design goal of the refurbishment, and is determined by blower-door tests before and after renovation. This paper presents air-tightness results from a demo case study in Norway. In the demo case the airtightness as determined by blower-door tests quite unexpectedly deteriorated, while the design goal for the projects was a major improvement. Probable causes for the discrepancy are discussed, and include leakage from the ground, in element joints and in unplanned openings.