As part of the possible measures to achieve energy savings in the residential sector, the project also analyzed the effectiveness of air curtains, typically used in the tertiary sector, and defined the parameters to consider for their selection and installation. The study was conducted by equipping a “model” room in the “Energy Efficiency” laboratory of RSE’s Milan headquarters with numerous sensors, and evaluating the thermal consumption and temperature variations under various conditions of its entrance door: closed door, open door, open door with heated and unheated air curtain. The various tests were carried out both with and without people passing through the door.

The experimental results showed that, in Milan’s climate, a climate-controlled room with an open entrance of 3 m² can lose nearly ~11,150 kWh in winter, which is equivalent to the amount of energy needed to heat an apartment of ~100 m².

In summer, it can lose ~2,100 kWh, the energy required to cool two apartments of ~100 m². Using the air curtain device with an open door resulted in energy savings compared to the situation with an open door without the device, and the savings increased with the temperature difference between the indoor and outdoor environments, starting from a temperature difference of ~3 °C with an unheated air curtain and ~10 °C with an air curtain heated by an electric resistance.

The results show that leaving the entrance doors of a climate-controlled environment open leads to significant energy waste, which can be reduced by installing air curtain devices at the doors, provided that these devices have appropriate characteristics and are installed correctly. Some of the main recommendations for the proper installation of air curtain devices are provided in the final section of the report.