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conscious living: cool spaces 03 – cross ventilation

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces.

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Cross Ventilation

We discussed the importance of natural ventilation last week in cooling spaces. By having ample sizes and proper orientation of openings, natural ventilation can be introduced. But how does it really work?

Cross ventilation is forcing the wind, with its cool exterior air, into the space, and forcing the hot interior air out. The two important elements (aside from the wind) in inducing cross ventilation are the inlet and outlet.

Cross Ventilation: Illustration by Arch. Stanley Fernandez

The inlet and outlet are the openings we talked about last week, whether they are windows, doors, vents or other openings. The inlet is where the wind enters the space and the outlet is where it exits. To have air movement inside the space (comfortable enough like a cool gentle breeze), there must be an entrance and an exit for the wind to cross to.

Ideally, these two openings should never be side by side. (There happens to be no space to “cross” through.) Their locations should be either at opposite walls or perpendicular to each other. Consequently, it is always best for rooms to have at least two sides facing the exterior to satisfy this condition.

The inlet opening should at least face the direction of the prevailing wind. (That’s why we tackled proper orientation of spaces!) If for some reason it can’t, you can somehow redirect the wind to the inlet by placing “blocks” to bounce the wind right into the opening (of course, just not as efficient).

Try not to put blockages in the path of the wind from the inlet to the outlet. Push those tall furniture and decorative dividers away. And no, light partitions even if they are perforated, will greatly diminish the air speed inside the space. To have the maximum effect of cross ventilation, air flow should be unimpeded.

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