Ventilation in schools is very important as it has a direct relation to health and performance of pupils.The status quo of school ventilation in the Netherlands is presented: lots of problems and insufficientsituations were found. Different aspects of the problems were studied to find new solutions.A new Integral Design approach was developed to design adequate solutions for ventilation of school buildings.

The legal background for the assessment of the energy performance of buildings and energycertificates in Germany will be changed in October 2009. Beside the tightening of the requirements byabout 30%, a significant change will be made at the calculation of residential buildings. Up to now thecalculation has to be performed by using the so-called simple approach (EN 15603) by applying theoutdated European standard EN 832 in combination with the European Standard EN 14335 withnational boundary conditions.

In order to respond to global warming and natural resources depletion challenges, industrials from the building sector need to propose an adequate offer. Energy simulation tools can support this process. Various studies and real cases show that a high performance level, e.g. primary energy consumption below 50 kWh.m-2 per year (including heating, cooling, domestic hot water, lighting and ventilation), can be reached by appropriate architecture combined with high insulation, free cooling and heat recovery on exhaust air.

It is well known that appropriate ventilation represents one of the prerequisites for achieving goodindoor comfort, and we try to ensure a continuous and sufficient intake of fresh air into a building. But,ventilation losses are also one of the most important components of a building thermal balance, andwe try to reduce them as much as possible. In theory, these two seemingly contradictive facts can betechnically adequately solved in various ways.

Differences might arise between the design and the real load of ventilation systems during operation.Consequently, the fresh air demand usually varies over a wide range. In normal usage, different types of gaseous contaminants enter the air that might be hazardous to health. The constant inhalation of contaminated indoor air might lead to discomfort or to harmful physiological effects.The difference between the design and the real load can be diminished by augmenting the ventilation system with appropriate components and controls.

The Annex 46, within the IEA ECBCS programme, is meant to influence the decision making processin the retrofit of public and governmental buildings that determines the use of energy-saving measures in building retrofits. This decision making process must improve, if it is to successfully cope with the challenges of increasing energy costs and climate change, and if it is to avoid "locking in" long-term commitment to energy inefficiencies by adopting sub-optimal renovations.

The influence of ventilation on the energy performance of a building is generally considered to be quite high. It rises clearly, when a building contains large-volume spaces. A famous example building for that is the Reichstag building in Berlin, housing the German parliament. The huge plenary hall in the buildings centre, which occupies only 4% of the total net floor area but 20% of its net volume, is equipped with a powerful air-conditioning system.

For outsiders, a national energy performance (EP) requirement level is quite a black box. Within the EU Asiepi project (www.asiepi.eu) we are developing a methodology to make a comparison of EP requirement levels possible among member states of the EU.An unexpected finding has been that far from all EU countries consider all energy uses in their EP method required by the EPBD (Energy Performance of Buildings Directive). The energy use for fans, domestic hot water and cooling are among the energy uses which are not taken into account by various countries.

The indoor air quality is a very important issue and it generally depends on the airtightness of theshell, the ventilation rates, the deposition and the resuspension rates of the particles and the internalsources as well.The whole experimental procedure took place in a PASSYS test cell, which is located at the University Campus of Athens.

Renovation of existing buildings, in order to reduce energy consumption, represents a big market inEurope. As the first efforts often concentrate in improving insulation and airtightness of the buildingenvelope, important insufficiencies of ventilation can appear, generating health risks for the occupants and a degradation of the frame. Taking into account the difficulties to insert ductworks in existing buildings, it can be easier to use distributed ventilation systems for room-by-room ventilation instead of centralised systems.