The 32nd AIVC and 1st TightVent Conference - Towards Optimal Airtightness Performance,  was held in Brussels, Belgium, 12-13 October 2011.

The 26th AIVC Conference, Ventilation in relation to the energy performance of buildings, was held in Brussels, Belgium, 21- 23 September 2005.

Many countries will between 2015 and 2020 have regulations imposing requirements for new buildings which are near-zero energy targets. This has major consequences:

The workshop highlighted the status, classical approaches and new concepts covering areas where intelligent analysis techniques can be used for the following topics: 

Ambitious targets on transforming the building stock into a highly energy efficient and low carbon environment demand also very performing scientific tools for the evaluation of the energy performance of improved building envelopes and construction techniques. Full scale testing becomes –again- more relevant, in combination with dynamic analysis and numerical simulation tools.

The energy and environmental challenges ahead of us are tremendous; a reduction of the heat flow through opaque building elements remains a top priority. This is not only the case for new buildings but even more for existing buildings. Whereas in the past insulation layers in the building envelope yielded rarely more than 100 mm of thickness, the tightening of the requirements and targets will lead to substantially thicker layers with classical insulation materials. Especially for renovation, the thickness of internal or external insulation layers becomes a major issue of concern.

While it is generally accepted that a ventilation system in a building—whether natural, mechanical or hybrid—is needed to provide acceptable indoor air quality and prevent building damage, there are debates about the actual performance of these systems and how the deviations observed affect the overall buildings performance and the well-being or safety and health of the occupants. These debates are increasingly active given the sensitivity of new and renovated buildings on energy use and indoor air quality depending on the field characteristics of ventilation systems.

The current development in building energy efficiency towards nearly zero energy buildings represents a number of new challenges to design and construction of buildings. One of the major new challenges is the increased need for cooling present in these highly insulated and airtight buildings, which is not only present in the summer period but also in the shoulder seasons and in offices even during occupied hours in winter. In most post‐occupancy studies of high performance buildings in European countries elevated temperature levels is the most reported problem, especially in residences.