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The feasibility of good air-tightness in new buildings can be determined based on the obtained air tightness classes as defined in EN 12237. In this paper a model is described which allows to calculate the energy loss caused by leak losses in ventilation systems based on the air tightness class and the feasibility of realising a good air-tightness.
The air-tightness of the ventilation system is building specific as it is preliminary determined by the lay-out of the system and thus by the air-tightness of the used components. Therefore an inventory of the ventilation system components is used to calculate the air losses. If no inventory is available, the model is able to estimate the losses based on square meters floor space and building type.
The total energy cost related to the preconditioning of supply air and the transportation of supply and exhaust air depends on a number of parameters. Some of these parameters are climate-related and therefore fixed, some are case-specific and can be altered by the user (e.g. internal humidity requirements, working hours, type of heat recovery, unity cost energy). The air leak losses have the same unity-cost for transportation and preconditioning as the wanted air.
In this paper the method is applied on three cases: a hospital wing, a rest home and an office building. The simulations show that the total energy consumption related to ventilation can be reduced by over 30% by achieving an airtight ventilation system. Good air-tightness of ventilation systems offers real added value as obtaining good air-tightness lower energy costs and a better indoor comfort. The additional investments to achieve a good air tightness of the ventilation system in new buildings are low compared to the avoided energy losses.