Who this guide is for
- People whose homes overheat in summer
- Owners planning shading or glazing changes
- Anyone interested in passive cooling concepts
- Those preparing to discuss options with professionals
How Solar Heat Gain Works
Solar heat gain happens when sunlight enters through windows or warms surfaces, raising indoor temperatures. South- and west-facing glass often gathers the most heat in the warmer months, depending on hemisphere and orientation.
Understanding where and when sun hits the home is the basis for deciding where shading helps most.
- Sun entering glass warms interiors
- Orientation strongly affects heat gain
- Timing of sun matters as much as direction
Shading Strategies
Shading intercepts sun before it heats the inside. Options range from overhangs and exterior shading to plantings, blinds and shutters, with exterior shading generally more effective at stopping heat than interior coverings.
Choosing shading suited to a window's orientation and the season is what makes it effective rather than incidental.
- Overhangs and exterior shading devices
- Plantings that shade in summer
- Blinds and shutters as additional layers
Glazing and the Building
The glass itself and the building's makeup affect how much heat enters and lingers. Glazing choices and the home's thermal behavior are part of the picture, though these are technical decisions for professionals.
Considering glazing alongside shading gives a fuller approach than treating either alone.
- Glazing affects how much heat enters
- The building's thermal behavior matters
- Glazing decisions are professional
Plan Passive Before Mechanical
Reducing heat gain first means any cooling has less work to do. Planning shading and passive measures before, or alongside, mechanical cooling can make a home more comfortable and efficient.
Because the right mix depends on the home and climate, this is a planning conversation to have with professionals.
Solar Heat Gain Planning Checklist
- 1Note which windows gather the most sun
- 2Consider orientation and time of day
- 3Plan exterior shading where it helps most
- 4Consider plantings that shade in summer
- 5Add blinds or shutters as further layers
- 6Consider glazing alongside shading with professionals
- 7Plan passive measures before mechanical cooling
- 8Adapt the approach to your climate and home
Common mistakes to avoid
- Relying only on interior blinds to stop heat
- Ignoring orientation when planning shading
- Treating glazing and shading as unrelated
- Reaching for cooling before reducing heat gain
- Assuming one approach suits every climate
When to involve a professional
- Glazing, structural and system work belongs with professionals.
- Specifics depend on orientation, climate and the home.
- This page explains concepts, not work to perform.
- Costs and timelines vary; this page does not estimate either.
Frequently asked questions
Questions readers ask about this topic
What is solar heat gain?
It is the warming of a home's interior when sunlight enters through glass or heats surfaces. South- and west-facing glass often gathers the most heat in warmer months, depending on orientation and hemisphere.
Is exterior or interior shading better?
Exterior shading is generally more effective at stopping heat before it enters, while interior blinds and shutters add a further layer. The best choice depends on the window's orientation and the season.
Does glazing affect heat gain?
Yes. The glass itself and the building's thermal behavior affect how much heat enters and lingers. These are technical decisions for professionals, best considered alongside shading for a fuller approach.
Why reduce heat gain before adding cooling?
Reducing heat gain first means any cooling has less work to do, which can make a home more comfortable and efficient. The right mix depends on the home and climate, so plan it with professionals.
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