ventilation system choice

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 resista