Ventilation
Thermal comfort can be created by increasing air speed through cross ventilation, which promotes evaporative cooling of moist skin. In addition, the placement of openings for inlet and outlet of air is essential for directing the air current to the occupation zone and the presence of ventilated attic spaces, preferably with some ceiling insulation, reduce radiative heat transfer from the roof sheeting. Wind angles up to 45° to the openings are acceptable and may even give better ventilation rates than in a perpendicular direction.
- in Nome (Alaska) the ventilation rate should be kept at a minimum to reduce heat losses, but not so low that it causes health or moisture problems;
- in Nadi (Fiji Islands) adequately placed and designed openings can direct air-flow into the spaces normally occupied.
Structural cooling by night ventilation has been commonly adopted in hot and arid regions: during the daytime, a sufficient amount of internal building mass can serve as a heat sink to absorb, by radiation and natural convection, the heat penetrating into and generated inside the building. As a rule of thumb, night ventilation can create an indoor maximum temperature of 7–8 K below the outdoor maximum; during daytime, when the building is closed, the thermal mass is cooler than the indoor air, making the operative temperature lower, further enhancing the comfort.