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Blinds/Curtains/Shades

Engineering Inputs

David Speedlin avatar
Written by David Speedlin
Updated over a year ago

The Blinds/Curtains/Shades input is used to determine the shading device factor (SDF), a factor that directly impacts the solar transmittance of all the windows. Different from the shading coefficient, which is the ability of a window covering/shading to reduce heat gain, SDF reduces solar access. A window covering with an SDF of 0.35 will obstruct about 65% of the daylight (lux), therefore, the lower the shading coefficient, the better the efficiency of a window cover.

analysis.tool uses ISO 13790 Annex G.5.2 for the shading reduction factor calculation.

  • (Exterior) Blinds: Outdoor shades to limit the excessive daylight coming into space. SDF = 0.35, or colored screens/ white Venetian blinds outside the envelope.

  • (Interior) Blinds: Indoor shades to limit the excessive daylight coming into space. SDF = 0.5, or white Venetian blind inside the envelope.

  • No Blinds: No Shades for the building. SDF = 1.0, or no shading device/ white textiles inside the envelope.

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