Passive Envelopes
Semi-arid climates, using Trombe wall as a low-tech passive heating and cooling solution. In this study, we made developments to the conventional classic Trombe wall using occupant-centered design and living lab experimental methods. The thermal efficiency of the proposed Trombe wall design is simulated during winter and summer peaks.
Francesca Stazi, in Thermal Inertia in Energy Efficient Building Envelopes, 2017
5.3.2.1 Behavior of the wall in summer, cloudy and sunny days
Trombe walls are convenient systems in Mediterranean climates in terms of energy performances and thermal comfort but proper measures should be taken to avoid the summer overheating drawbacks that could occur due to high heat gains. This section shows through measures that the adoption of external screening is more efficient than the maximum exploitation of the solar chimney by enhancing the buoyancy effect through high solar gains.
Figs. 5.40 and 5.41 reports the results of the summer monitoring of two Trombe walls realized in the southern exposure of the same room, but used in two different ways: one with closed shutters and the other in unscreened condition. Both walls were cooled by the ventilation of the external gap through the cross-ventilation with the openings facing to the northern side of the room. Fig. 5.40 reports the weather conditions of the monitored period. Fig. 5.41 shows that the closing of the external shutters reduces the internal surface temperatures of the wall (Tsint) of about 2°C. The air temperature inside the room is very close, and sometimes higher, than the surface temperature of the screened wall. So the wall can play its beneficial cooling effect.
Regarding the activation of the buoyancy force, it is clearly more effectively activated in the unscreened wall as demonstrated in Fig. 5.42. Indeed in this case there are higher temperature differences between the air in internal room (that is within the range of 23–25°C as seen in the previous figure) and in the air gap at middle height of the wall (ranging between 24 and 34°C in the unshaded wall and between 23°C and 29°C in the shaded wall).