This guidance note explains that it is the visible light transmittance that is the relevant measure of light ingress through a fabric rather than the openness of the fabric.
Download here: BBSA Guidance Note 17A – Openness Coefficient
This guidance note explains that it is the visible light transmittance that is the relevant measure of light ingress through a fabric rather than the openness of the fabric.
Download here: BBSA Guidance Note 17A – Openness Coefficient