Solar passive design is a sustainable approach that uses a building’s design, layout, siting and construction materials to naturally control indoor temperature. This minimises or eliminates the need for mechanical heating and cooling systems. It works with the local climate to create comfortable, energy-efficient spaces by managing sunlight and heat rather than relying on energy-intensive technology such as air conditioning or heaters.
Orientation: The house’s long axis is oriented east-west with primary living areas and windows facing the equator (True North in the Southern Hemisphere, True South in the Northern Hemisphere). This maximises winter sun exposure.
Shading: Verandas, overhangs, eaves, pergolas, awnings, sun-hoods/shrouds and louvres designed to block the high-angled summer sun while allowing the low-angled winter sun to enter.
Thermal Mass: High heat capacity materials such as concrete, brick, tile and stone are used inside the building to absorb solar heat during the day and release it at night when temperatures drop.
Insulation: High-performance insulation and draught sealing are crucial for retaining stored heat in winter and keeping heat out in summer.
Glazing: Strategically placed, high-performance windows allow sunlight in while minimising heat loss.
Natural Ventilation: Windows and openings are positioned to create cross-ventilation, enabling the building to cool itself by letting breezes pass through.
What it means for the user:
Active Users for Passive Design: Passive solar homes often require active inhabitants to function optimally. For example, closing windows and blinds on hot summer days and opening them to release heat on summer evenings.
Comfort Without Mechanical Help: The aim is to maintain a comfortable, natural interior temperature range of 18°C–28°C by taking advantage of natural sun and wind patterns.
A “Fabric First”: approach prioritises the building envelope – walls, windows and roof – before considering auxiliary heating or cooling. Properly implemented, these strategies can significantly reduce heating and cooling energy usage by up to 40% or more.
While both aim for similar outcomes, Passive Solar Design focuses on harnessing natural, free and available solar energy often without stringent performance requirements. Conversely, Passivhaus (Passive House) is a rigorous certified building standard demanding strict airtightness, high-performance insulation and specialised ventilation systems (MVHR).