The paper deals with the feedback of the measurements conducted in the first zero energy building "EnerPos" constructed in the French tropical Island of La Reunion. The building was designed to operate as long as possible by using passive techniques (cross natural ventilation, day-lighting). The purpose was to reach an annual energy ratio below 55kWh/m² (which is three times below the mean ratio of standard buildings in La Reunion) by avoiding energy consuming active systems such as air-conditioning and artificial lighting.

The building was inaugurated in January 2009 and since, a post-occupancy evaluation was carried out in terms of thermal, visual and air-speed comfort. First, a comfort survey was conducted on the users : altogether, about 500 students and teachers answered more than 1500 questionnaires, which included questions concerning their personal information (clothing, previous activities) and their comfort at the beginning and at the end of the exposure. The students were asked to express their sensation and judgment for the thermal, hygrometric and air speed comfort. At the same time, the main environment parameters (air temperature, black globe temperature, humidity, air speed and illuminance) were being recorded. The outdoor climatic data were also collected thanks to a meteorological station located on site. The results show that the users feel comfortable when the temperature is below 30°C with an air-speed close to 1m/s. It is then possible to reach a thermal comfort for the users in the classrooms and offices even during the hottest days of the year. Nevertheless, the air-conditioning is needed in the computer rooms during the six hottest weeks of the year (from the end of January to the beginning of March) due to the heat produced by the computers.

Two measurements campaigns were also conducted to assess the visual comfort of the users and to determine the autonomy in day-lighting during summer and austral winter in every rooms of the building. The results show that the autonomy during the hours of occupation is about 80% in the offices, 70% in the most disadvantageous classrooms (on the first floor) and can nearly reach 100% on the second floor. Lastly, the performance of the ceiling fans was measured to evaluate their circles of influence (in which an air-speed of 0,7m/s is reached).