Extraction demand control ventilation is a simple, cost-effective and robust technique for building refurbishment of residential buildings. However, extraction ventilation for a central and northern Europe cold climates, taking the air directly from the facade, may result in cold drafts for the occupants. RECO2ST project includes in its refurbishment kit of innovative technologies a smart window, preheating the air, in the gap between a triple glazing construction, with the interior glazing openable for visiting the air passage. The Suisse demonstration case selected a demand control ventilation system as a cost optimum solution. The article presents the results of an in-situ experimental study on the demonstration building in Switzerland where a comparison of the air quality and energy performance are made. The measurements were carried out on three similar apartments, one with the smart window and two others with different smart air inlet strategies. The experimental results demonstrate that all three tested air inlet strategies perform much better than a simple air inlet of 30 cm2, which is a very common model in the market and creates cold drafts for the occupants. The demonstrated RECO2ST smart window, additionally to this advantage, pre-heats the air and recovers part of the window heat losses and solar gains and the demo case showed that it may be perfectly combined with a DCV extraction ventilation system. The standard air inlet with humidity control performs in reality according to specifications, offers a good air quality and does not provoke cold droughts. Proven smart technologies for air inlets, addressing the issue of cold draft risks, make demand control ventilation, which is a cost-effective solution for residential building refurbishment, more reliable and acceptable for the occupants.