Which three envelope strategies are effective for controlling heat gain in tropical climates?

• A. External shading (overhangs/brises-soleil), high-performance low-SG glazing, and well-sealed but ventilated walls with appropriate insulation where needed.
• B. Large glass walls, no shading, and airtight insulation at all times.
• C. No shading, single glazing, and no insulation.
• D. Thick masonry only without any glazing.

Answer: (A)

In tropical climates, the goal is to stop heat from entering the interior while still letting daylight and ventilation work for comfort. External shading, like overhangs and brises-soleil, blocks a large portion of the sun before it can heat up walls and windows. This reduces the amount of solar radiation that reaches interior surfaces, cutting heat gain at the source.

High-performance glazing with a low solar heat gain (low-SG) coefficient minimizes the amount of heat that passes through the glass while still admitting daylight. This keeps interior spaces brighter without pulling in as much solar heat as ordinary glazing would.

Walls that are well-sealed yet ventilated, and properly insulated where needed, limit unwanted heat entering through conduction and envelope leaks, while still allowing controlled air movement to remove heat and humidity. The insulation reduces heat flow, and the ventilated design helps with cooling and moisture management without compromising comfort.

Together, these strategies address the main heat-gain pathways—solar radiation, radiant heat through glazing, and conductive heat transfer—while supporting natural ventilation and daylight. The other options either ignore shading, rely on less effective glazing, or lack appropriate balance between mass, glazing, and ventilation, leading to higher heat gains.