Defines the way that light transmits and reflects off of an object or material.  When light is transmitted or reflected it can have specular components and diffuse components.  A BSDF file is used by daylight and energy modeling software to characterize how light interacts with a material such as glass or shade fabric.  This detailed property file allows more accurate estimation for energy performance, daylight availability, and rendering accuracy in these tools.

The percentage of business hours where the required illuminance can be delivered by daylight alone. In other words, it helps understand for a particular point on the office floor, what percentage of work hours can the lighting needs be met from daylight alone.

DGP is the probability of a person or group of persons perceiving some level of glare at a given location and view angle

• 0.50 – Critical
• 0.45 – High
• 0.40 – Medium
• 0.35 – Low

A DGP of 33% indicates that there is a 1/3rd likelihood of the occupant (or 33% of the occupants) noticing some level glare. Although this may seem high, with a DGP of 33% the level of glare perceived by the occupants is typically considered “nearly unnoticeable” meaning that it would not affect day to day activities. Conversely, when the DGP exceeds 50%, the level of glare perceived by the occupants is typically considered “very uncomfortable” meaning that it would likely cause serious disruption in day to day activities.

Openness factor describes the percentage of light that transmits directly through the fabric. It can be approximated by the percentage of open space in the weave. Simply stated, it varies based on how tightly fabrics are woven - the tighter the weave, the less daylight filters through.

The published values for openness factors are typically nominal or approximate values used to give a general indication of the weave tightness. Although useful, these are not sufficient for evaluating the shading system performance (glare, daylight, and views). Look for the mean openness factor values for accurate performance evaluation.

There are typically three types of fabrics classified by openness factor – Sheer, Translucent/Dim-out, or Blackout fabrics.

• Sheer fabrics have a high transparency, and the openness factor is 1% or higher. Common nominal openness factors for sheer shades are 1%, 3%, 5%, and 10%. These fabrics allow daylight to enter a space and provide a view to the outdoors.
• Translucent or Dim-out fabrics, also referred to as privacy fabrics, have an openness factor between 0% and 1%. These fabrics let in a limited amount of daylight. A view outside will have very little detail - you will only see shapes and shadows.
• Blackout fabrics, or opaque fabrics, have a 0% openness factor and block 100% of daylight. Commercially, blackout fabrics are often used in conference room applications to allow for presentations or video conferences. For total blackout, a side channel is required.