Optimization method for the ventilation system choice in zero energy buildings

Developing a method to optimize the investment cost of a building and the energy performance, represented by the energy consumption, one gets easily confronted with conflicting objects.  As the investment cost usually rises, while the energy consumption shrinks it is somehow difficult to find an optimal solution.  The utopic point would be the point where saving energy doesn’t cost athing, or even better: earns the occupant extra money.  Reality however shows different: restricting the energy losses almost always implies an investment.  The simplest example is increasing the thermal resistance of the building envelope ((i.e. walls, roofs, floors, windows and airtightness).  Since this paper handles about the ventilation system choice in zero energy buildings, it can be said that no further addition of insulation of airtightness is needed, because the heat losses through the building envelope have already been restricted to a minimum.  The main issue in this paper is the control of heat losses due to the ventilation rate of the ventilation system, albeit purely hygienic or not.This paper presents a methodology for ventilation systemselection  based on the total investment cost for the system and effect it has on the energy consumption of the building. Former research has shown that the choice for a cost optimal ventilation system depends on the total energy demand of the building. The proposed method makes it possible to compose a random combination of parameters (insulation thicknesses, U-values (thermal transmittance) of windows and airtightness) and calculate the heat losses through the building envelope. Through this loss of heat, the energy consumption or energy demand for the building can be calculated and an optimal choice for the ventilation system can be made, taking into account the additional cost and the system efficiency.