CLTC releases new Daylight Harvesting Guide
New CLTC Publication on Daylight Harvesting for Commercial Buildings
The CLTC is excited to announce a new publication in our Lighting Best Practices series, the Daylight Harvesting for Commercial Buildings Guide! This publication provides guidance towards meeting and exceeding California's Building Energy Efficiency Standards for daylight harvesting.
Daylight design guidelines and associated Energy Standards are provided in an easy to read, side-by-side layout, organized into sections for each building-related discipline that impacts daylight performance from building siting, through architectural and interior design, to construction, commissioning and operation.
This publication was developed with support from Southern California Edison and the California Energy Commission. Support was also provided by the University of California, Davis 
Publication Date: 08/27/2018
Download the guide 90 page PDF
Glare - consider glare in your daylighting design
Glare is the effect of brightness or differences in brightness within the visual field sufficiently high to cause annoyance, discomfort or loss of visual performance.
Glare – Disability Glare
If task performance is affected, it is called disability glare
Glare – Discomfort Glare
Visual discomfort caused by excessive brightness is called discomfort glare.
Glare – Direct Glare
Glare resulting from very bright sources of light in the field of view. It usually is associated with bright light from luminaires and windows. A direct glare source may affect occupant’s performance by reducing the apparent contrast of objects in the field of view, especially those near the source of light.
Glare – Indirect Glare
Glare produced from a reflective surface.
Glare – Reflected Glare or Veiling Reflection
Glare resulting from bright reflections from polished, glossy, or illuminated objects and surfaces in the field of view. Veiling reflections reduce visual contrast and make it difficult to complete seeing tasks such as reading glossy magazines or looking through windows or at computer screens. Often windows or light fixtures will reflect off surfaces obscuring what is beneath, anticipate this visual obstacle by careful placement of lights, windows, and tasks. Remember with glare, 'the angle of incidence equals the angle of reflection' just like billiards.
Visual Comfort Probability (VCP)
A rating system for evaluating direct discomfort glare. This method is a subjective evaluation of visual comfort, when viewing from a specific location and in a specified direction, expressed as the percent of occupants of a space who will be bothered by direct glare. VCP allows for several factors: luminaire luminances at different angles of view, luminaire size, room size, luminaire mounting height, illuminance, and room surface reflectivity. VCP tables are often provided as part of photometric reports.
Join us on June 21, 2019 by turning off the lights for one hour.