Testing the ventilation efficiency of room ventilation units with tracer gas methods.

With the improvement of thermal building Insulation the percentage of energy losses due to air exchange becomes an increasingly· important factor in building energy demand. In order to optimize infiltration and ventilation and to minimize the energy demand of low energy buildings, it is necessary to install an appropriate mechanical ventilation system. Different ventilation strategies can be used: Extract ventilation and supply I extract ventilation systems for buildings as well as single-zone ventilation units with or without heat recovery. All systems will only operate correctly, if each component is working as expected. Several room ventilation units with heat recovery have been investigated by using the tracer gas technique. Severe malfunctions were discovered, which significantly influence indoor air quality and building energy performance.