Digging deeper into glare, visual comfort (and discomfort), and electric lighting.
Slides are here.
What is glare? A subjective visual discomfort. Light within the fov that is brighter than what the eyes are currently adapted to. Three categories: disability glare (so high that you can't see, e.g. glare off a swimming pool for a lifeguard), discomfort glare (feeling slightly strained), veiling reflections (subset of former two, when reflectances of specular surfaces act as glare sources).
The "Walkie Talkie" skyscraper in London actually melted part of a Jaugar next to it due to the glare.
If everything is lambertian, you typically don't get glare. It's more common with mirror-like surfaces.
SpectralDB is a site that provides lighting material definitions for simulation.
Glare is hard to detect because its view-dependent. The holy grail is the glare index. How likely is it that someone is experiencing glare from a given view. We measure with DGP (complicated formula). DGP < 35%, imperceptible. DGP > 45%, intolerable.
We can have great daylight availabiliy but still need to improve the design because of the glare. We have to find the fine line between tolerable discomfort and visual interest.
A lot of times glare can be avoided by just giving people the flexibility to move around in a space.
Veiling reflectance. Think of when the sun is shining on your phone screen. The contrast ratio between the brightest and dimest. Higher ratio (iphone in the dark) is better.
Everyone knows what a good view is, but there are no well established metrics to evaluate. LEED has a very pedantic measure involving a ninety degree viewing angle to two glazings. Can also measure in terms of visibility and sky exposure.
Daylighting Pattern Guide could be a good resource.
Slides are here.
The two main things people can do to control light are open/close blinds and turn lights on/off.
Single biggest opportunity to save buildings in energy today: make sure the systems are turned off when nobody is there. It seems banal and trivial but there is lots of opportunity.
Any of the light that can been seen in the pictures of earth from space is completely wasted, its going into space no nobody on earth is seeing it.
The key moment for lighting is when a space is entered. That's when the light's will be switched on or not. So doing things like controlling the surrounding brightness can be very important.
Two types of light users: passive (always turn on the light), and active (preference for daylight). At the building level there is suprising consistency however. At 300 lux, the chance of the lights coming on is less than 10%.
Lightswitch -- an algorithm to probabilistically tell you whether lights will be turned on or off in a simulation.
Blinds are closed when there is glare or when it is just too bright in a space.
11% of electricity use in the U.S. is for electric light. In the commericial sector its 19% of total electricity consumption (14% in residential).
ASHRAE 90.1: standard for designing for lighting. A very important standard, any commercial building in the US will have to meet this standard.
Lighting Power Density, e.g. 20 watt per square meter. "How much do I use in the worst case scenario". Designers don't like this because you might design a "scene" where you only ever expect to have some of the lights on.