Define passive cooling and provide a tropical-building example.

• A. Cooling achieved without active mechanical systems; e.g., cross-ventilation through operable windows with shaded facades.
• B. Cooling achieved solely by HVAC systems.
• C. Cooling achieved by increasing insulation only.
• D. Cooling achieved by combining passive strategies with minimal mechanical support as needed.

Answer: (A)

Passive cooling uses natural forces and architectural design to lower indoor temperatures without relying on mechanical cooling. In tropical buildings, this often means letting the breeze move through the space and reducing heat gain with shading. An example is cross-ventilation achieved by operable windows or vents that align with the prevailing wind, combined with shaded facades to cut down solar heat. This setup lets outdoor air flow through the interior, cooling it naturally and reducing the need for air-conditioning.

The other options depend on active systems or focus only on insulation, which by itself doesn’t actively cool the space. A hybrid approach that adds some mechanical support isn’t purely passive, so it isn’t the best answer when defining passive cooling.