Specifier Tools

Daylight Factor Calculator

Estimate the average daylight factor of a room using the BRE method, and read it against practical daylighting bands — live, as you adjust the room.

Room & Glazing Inputs

Glazing transmittance (T, diffuse)

0–1

Net glazed area (W, glass only)

m²

Angle of visible sky (θ, from window centre)

Interior surface area (A, walls+floor+ceiling+windows)

m²

Area-weighted average reflectance (R)

0–1

Average Daylight Factor

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