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conscious living: cool spaces 04 – stack effect

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.

Stack Effect

Hot air rises. Cold air sinks.

In essence (and without getting too technical), this is what stack effect means in tropical climates. It is a scientific fact that air movement in interior spaces follows these directions: up for hot and down for cold.

How does stack effect influence the design of spaces?

Illustration by Arch. Stanley Fernandez

Let’s start with a typical room. Having taller or higher windows allows hot air to escape above. It also implies that a higher ceiling is beneficial in keeping the heat as far away from the living zone.

(This is also the main reason why air-conditioning units should be placed above or near the ceiling, so the cold air could naturally sink and not overwork the motor. Overworking the motor leads to consuming more energy. But we’re advocating natural ventilation here as much as possible.)

If the building or house is multi-story, the ground or lower levels are usually cooler than the floor right under the ceiling. Place the important spaces (or where you spend the most time in) on the cooler levels.

In his own home, National Artist for Architecture Bobby Mañosa located the bedrooms on the ground floor. To him, having a cool, comfortable space to rest and sleep in is more essential. The living room, dining room and kitchen are located above (which are quite open and ventilated too).

Stack effect can also be used to divert the hot air out of the space. Chimneys or flues can act as passages for heat to rise and escape. Since chimneys are quite impractical in this climate, stairwells become the main avenue for the hot air. Ensure the release of hot air by providing egresses above the stairwell. The openings can be operable louvers or clerestory windows.

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