passivesolar

Passive solar design is a building approach that uses architectural features to collect, store, and distribute solar energy for heating, cooling, and daylighting, with little or no reliance on mechanical heating or cooling systems. Its aim is to reduce energy consumption while maintaining comfortable indoor conditions.

Its core principles include proper siting and orientation, typically with a long south-facing façade in the northern hemisphere to maximize winter sun exposure; the use of thermal mass—such as concrete, brick, stone, or water—to absorb heat during the day and release it when temperatures drop; deliberate spacing and sizing of windows to balance heat gain with insulation; effective insulation and airtight construction to minimize heat loss; and design features for shading and natural ventilation to avoid overheating and to support cooling when needed. Daylighting is often integrated to reduce electric lighting.

Techniques commonly employed are direct gain, where sunlight enters living spaces through south-facing glazing and directly warms the interior; indirect gain, using thermal mass behind glazing (for example a Trombe wall) to moderate temperature; and sunspaces or attached insulated spaces that collect solar heat and transfer it to the main living areas (isolated gain).

Passive solar design is well suited to temperate climates with distinct heating needs but can also contribute to cooling savings in hot seasons with shading and ventilation strategies. Benefits include lower heating and lighting energy use, improved comfort, and greater resilience. Limitations include climate dependence, site constraints, and potential up-front costs or architectural constraints related to window area and thermal mass placement.

Over the 20th century, passive solar concepts influenced modern energy-efficient building design and remain a foundational element of sustainable architecture. Programs and guidelines in various regions promote passive solar principles as part of broader green building standards.