Survey of mechanical ventilation systems in 30 low energy dwellings in Germany.

This paper shows preliminary results of 18 out of 30 inspected ventilation systems in low rise, low energy residential buildings. We propose a method for the assessment of energy efficiency of ventilation systems. The majority of the inspected exhaust systems fulfills the conditions for the demanded air flow rates and energy efficient operation. However, typically the distribution of airflows to the rooms of the supply zone is rather weather dependent due to insufficient airtightness of the buildings and large stack heights. 2 of 5 exhaust supply systems with heat recovery mismatch energy efficient operation due to high pressure drops. The airtightness of the buildings is insufficient. Generally, there is a lack of operation and maintenance instructions. By optimized ductwork, fans, motors and controller theelectricity consumption could be reduced by more that 50%.