The Proceedings of the 32nd AIVC Conference " Towards Optimal Airtightness Performance", held in Brussels, Belgium, 12-13 October 2011.

This paper presents some first approaches for the national application of the nearly zero-energy building definition according to the Energy Performance of Buildings Directive by summarising the current plans of Germany, Denmark, Ireland and the Netherlands. As a contribution from a 5th country, the planned national energy performance requirements of Switzerland for the phase from 2018 onwards were included. It was also analysed whether any of the countries will set specific requirements to the air-tightness of NZEBs and if there are specific requirements for ventilation techniques

It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of "good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard.

The EPBD (EU Energy Performance of Buildings Directive) Concerted Action is a cooperative effort from all 27 EU Member States (MS), plus Norway and Croatia, together with the European Commission. It is running since 2004, under the Intelligent Energy programme since 2007. It aims at providing support to MS in their effort to transpose and then implement the EPBD, identifying the best solutions and practices that MS can then adopt and thus move towards harmonization throughout the EU.

Today an acceptable indoor air quality is mainly defined by specifying the required level of ventilation in air changes per hour or the outside air supply rate. This would be equivalent to defining the requirements for thermal comfort by specifying the level of heating or cooling in Watts. The increasing societal need for energy efficiency will often result in very tight buildings. This means that the amount of outside air supplied by infiltration is not enough to provide the required ventilation.

A retrofit study was conducted in an unoccupied manufactured house to investigate the impacts of airtightening on ventilation rates and energy consumption. This report describes the retrofits and the results of the pre- and post-retrofit assessment of building airtightness, ventilation, and energy use. Building envelope and air distribution systems airtightness were measured using fan pressurization. Air change rates were measured continuously using the tracer gas decay technique.

The airtightness of inclined roofs is important in order to avoid hygrothermal problems and to guarantee the durability of the construction itself. Previous research in building physics showed that perfect airtightness of inclined roofs is difficult to achieve and maintain. In practice, air transport through the construction, i.e. in/exfiltration, cannot be avoided due to for example imperfections or bad workmanship. The heat and moisture conditions in the building component are strongly influenced by advection, i.e.