Which type of solar heating requires careful placement of windows?

• A. Active solar
• B. Solar thermal
• C. Passive solar
• D. Hybrid solar

Answer: (C)

Passive solar heating relies on the building’s design, especially window placement, to collect and store heat from the sun. Large, well-insulated windows on the sun-facing side (typically south in the northern hemisphere) allow meaningful solar gain during colder months. The heat that enters is stored in thermal mass materials like concrete, brick, or tile, which absorb heat by day and release it gradually at night to keep interiors warmer. Proper shading and overhangs are also used to block hot summer sun, preventing overheating. Because there’s minimal mechanical equipment to move heat around, where you place windows and how big they are directly determines how much solar warmth you gain and how it is distributed. Active solar uses pumps and collectors, solar thermal focuses on heating a fluid for hot water with collectors, and hybrid systems combine passive design with active elements—so they don’t hinge on window layout to the same extent.