The same building but without OVF modules was used for comparison purposes. In this building the ventilation was taken directly from outdoor. The same ventilation strategy as the first building was followed and the openings had the same dimensions as all the OVF trap doors in the first case. Thus, both buildings were comparable regarding the use of outdoor air for ventilation.
In order to determine the influence of temperature, solar radiation and wind speed on the heating MK-2048 saving a two-way ANOVA analysis was carried out. This kind of analysis gives information about the influence of the variables considered and its interactions on the system output . For this purpose a matrix of cases with three variables with five levels each was built, yielding a number of 125 cases. The levels were selected equally spaced between the minimum and maximum day evolution of the variable found in the weather data files used for this study. Both buildings, with and without OVF were simulated in each case. In Fig. 4 the levels of temperature, solar radiation and wind speed can be seen. The simulation period was one day and the time step was 1 h.