The main aim of ventilation is to guarantee a good
indoor air quality, related to the energy consumed for
heating and fan(s). Active or passive heat recovery
systems seem to focus on the reduction of heating
consumption at the expense of fan electricity
consumption and maintenance. In this study, demandcontrolled
mechanical extract ventilation systems of
Renson (DCV1 and DCV2), based on natural supply in
the habitable rooms and mechanical extraction in the
wet rooms (or even the bedrooms), was analysed for
one year by means of multi-zone Contam simulations
on a reference detached house and compared with
standard MEV and mechanical extract ventilation
systems with heat recovery (MVHR).

To this end, IAQ, total energy consumption,
CO2 emissions and total cost of the systems are
determined. The results show that DCV systems with
increased supply air flow rates or direct mechanical
extract from bedrooms can significantly improve IAQ,
while reducing total energy consumption compared
to MEV. Applying DCV reduces primary heating
energy consumption and yearly fan electricity
consumption at most by 65% to 50% compared to
MEV. Total operational energy costs and CO2
emissions of DCV are similar when compared to
MVHR. Total costs of DCV systems over 15 years are
smaller when compared to MVHR due to lower
investment and maintenance costs.