SHGC (Solar Heat Gain Coefficient)

SHGC (Solar Heat Gain Coefficient) is a dimensionless number between 0 and 1 that measures how much solar radiation passes through a glazed unit into the building. A lower SHGC means less solar heat transmitted. A higher SHGC means more solar heat admitted, which can help passive winter heating but worsen summer overheating.

In residential NatHERS modelling for NCC 2022 7-star compliance, SHGC is one of the two key glazing inputs alongside the U-value (thermal resistance of the unit). The NatHERS modeller locks in SHGC values based on window product data sheets; changing the window specification after the model is run requires the model to be rerun and can break the star rating. SHGC values for rated windows are published in the Window Energy Rating Scheme (WERS) database.

In Australian residential practice, north-facing glazing often benefits from a moderate-to-high SHGC (passive solar gain in winter), while west-facing glazing usually requires a lower SHGC to limit afternoon heat load in summer.

Also known as: solar factor, g-value (European terminology)

Category: Glazing / energy compliance

NCC version transitions, where SHGC appears in the context of 7-star NatHERS and glazing specification timing

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