This study aims to evaluate the performances of a VMI, a demand-controlled mechanical supply ventilation system, in an experimental house, in terms of indoor air quality (IAQ), energy performance and thermal comfort. The positive input ventilation draws fresh air from the outside, filters and preheats or precools it before blowing it every dry rooms. The air circulates through doors’ undercuts and is naturally extracted thanks to exhaust orifices in every wet rooms. A heat exchanger supplied with water from a reversible heat pump is used to preheat or precool the blown air. On the one hand, this combination is expected to improve the IAQ by blowing fresh and filtered air in the rooms where occupants spend most of their time. On the other hand, the VMI is supposed to contribute to the thermal comfort by bringing or removing heat to or from the dwelling. To quantify the influence of the VMI on the parameters described above, a VMI and its heat exchanger are set up in an experimental house. The IAQ part is reduced to the analysis of the CO2 concentration in the experimental house’s master room, the relative humidity in the shower room and the PM2.5 concentration indoor and outdoor. The thermal comfort is reduced to the analysis of the supplied air temperature. Results are promising and show that the studied system is a good way to reduce stuffiness in the most occupied bedroom, evacuate humidity in the most occupied shower room and to reduce PM 2.5 level indoor. Results are also encouraging in terms of thermal comfort, since the VMI brings a significant part of the heat, enhancing thus the heating reactivity.