Venetian blinds must demonstrably meet the openness factor and transmittance value for blinds, where specified within a BREEAM manual. If the specification data for Venetian blinds is not available, evidence of the two points below can be provided instead:
1. The blind slats can be fully closed and overlap so there are no gaps between them.
2. The slat material clearly transmits no light, for example solid and opaque plastic, wood or metal.
If the slat material is not solid and opaque, and is for example, perforated or made from woven fabric, the openness and transmittance values must be demonstrated in line with the criteria.
