Cooling for tropical climates

Home cooling for tropical climates should be largely based on ventilation, shade and on the design elements associated with these elements: home orientation, fly-roofs, overhangs, floor-plan, roof and ceiling insulation, type of windows, fans and landscape…

Air conditioning

Air conditioning it too expensive to operate in tropical climates and should only be considered in specially focused cooling strategies. Often, it is used selectively, for a small part of the house (one or two rooms, say), during selected periods of the day.

Its role and the home design approach should follow the principles indicated for other hot climates.

See: Air conditioning for Hot Climates

Home Orientation

The home should be properly oriented to get breezes and sun protection.

If home orientation for exposure to breezes collides with sun protection, consider the possibility of deflecting the breezes (through vegetation, casement windows or wing windows and other means).

Design your landscape – with trees and shrubs - to funnel breezes into the building.

Ventilation and raised floors

Cross ventilation is a key element in most cooling strategies for tropical climates. To get it, it’s often advantageous to elevate the home structures (raised floors).

Orientation to the breezes (and their adequate channeling) is the key element for a good cross-ventilation.

Landscape & Shading & Breeze funneling

Consider your landscape carefully. Trees and shrubs, well located and chosen, should provide breeze funneling into the rooms that most need it.

You should maximize external shading, to prevent and reduce hot air infiltration through the walls or the ceiling, and to lower ground temperatures. Trees and shrubs, pergolas, trellises, patios with vegetation, overhangs, trombe walls or greenhouses are the most common elements of shading strategies.

Hot air ventilation at the ceiling level

The removal of inside hot air is crucial, and to get it (namely during periods of absence of favorable breezes) consider with care hot air removal.

Since hot air tends to raise (chimney effect), hot air removal can be provided by openings at the ceiling level of all rooms. Roof vents, clerestory windows (adequately shaded) and similar structures can provide that ventilation.

In case of metal roofs (they are a good option because they cool rapidly at night), use a sheet with a reflective coating on its underside, to reduce daytime heat gains.

Overhangs

Adequately sized overhangs are an important element of shading in tropical climates.

Insulation: roof and ceiling

Roof and ceiling insulation can be extremely important, to avoid heat gains during the day. Reflective insulation systems are usually very effective. Insulation should not prevent or delay too much the heat accumulated during the sunny hours.

Shading and fly-roofs

If possible, consider shading your home with a fly roof. It’s the most effective solution for heat gains at the ceiling level.

Bedrooms

Since sleeping comfort is a particularly important issue in hot climates, a proper bedroom cooling should deserve special attention in terms of home design.

Bedrooms should be located in the parts of the home that are less exposed to heat gains (the center of the home?). The airflow and the breezes should be channeled with priority for bedrooms.

If considering the use of air conditioning, bedrooms should be small and benefit from high levels of insulation (to avoid heat gains and cooling losses).

Floor plan

In many designs, single room depth and narrow buildings are advantageous. It will enhance cross ventilation and also heat removal.

An alternative – to facilitate cross ventilation - is to consider open internal surfaces.

See: Floor Plan for Cooling

Wall insulation and thermal mass

Wall materials with low thermal mass (materials that do not hold heat well, and cool rapidly) are a common solution for tropical climates. Wall insulation isn’t important or considered in that case (though reflective exterior surfaces are).

However, some designs may consider high thermal mass and insulation, namely in cases where cross-ventilation is insufficient to get thermal comfort and whenever air conditioning is part of the thermal solution.

Evaporative cooling

Swamp coolers or other methods based in the cooling effects of water (evaporative cooling) aren’t effective in tropical humid climates. They increase humidity, making the building yet more uncomfortable.

Windows and louvers

Windows should be large enough to enhance cross-ventilation and heat removal. And they should be shaded.

Windows should provide maximum opening areas (avoid fixed windows and windows with small opening areas). Louvers and casement windows are good options.

See: Cooling and Windows

Ceiling and whole house fans

Include ceiling fans in your cooling strategies. They will create ventilation during still periods.

Also consider whole-house fans, in cases where diurnal temperatures vary significantly. They can lower indoor temperatures by several degrees in just a few minutes... if outside temperatures are cool enough (whole-house fans are much cheaper to run than air conditioning)...