The architecture of light: architectural lighting design concepts and techniques. A textbook of procedures and practices for the architect, interior designer and lighting designer pdfdrive com

Designed Space Full Moon Light
Exterior Parking Lot Dim, romantic restaurant Comfortable Living Room Residential den / study Classroom / Open Office Laboratory / Exam Room
illuminance Level
0.1 Foot-candle
1.0 Foot-candle
5.0 Foot-candles 10-15 Foot-candles 20-35 Foot-candles 50-70 Foot-candles 100 Foot-candles
It is uncommon to light an entire interior space to Illuminance levels beyond 100 foot-candles. Once we start dealing with these higher illuminance levels, we are usually talking about light that would be applied to small areas of localized task. We may provide 200 foot-candles of light onto an operating table or an accented object, but it is unlikely that we would light an entire space to this level.
ADDING ILLUMINANCE VALUES TO A LIGHT MAP
Keeping these light levels in mind while designing and discussing light, will provide all of the intuitive knowledge needed to engage in discussions of light levels for basic spaces. With just this small amount of familiarity, one can start adding these values as targets for specific surfaces and whole room effects in
designed spaces. The suggested progression of design is to label these whole room and “specific surface” Illuminance level targets as a part of light map Layer 5 (See Ch. 4). Illuminance levels are best used to describe the quantity of light cast onto a surface, but they can also be used to give an impression of the overall ambient glow that one may perceive in a room. This can be put to use by mentally walking through the design, room by room, determining the overall ambient glow that is desired for each room.
Figure 19.1 Adding ambient illuminance level targets (shown here in green) helps to refine design goals.
In residential settings this process can be handled very easily. For spaces like residences that don’t have to support critical tasks, it is safe to use a limited range of illuminance values between 5 and 35 Foot-candles as targets for whole room ambience. You can reference the table above to see that these values cover most of the moods and environments we try to create in a residential setting.
These illuminance levels can also serve as the overall ambient glow for spaces
like restaurants, galleries, hospitality and museums. For more task oriented spaces, like open office areas, classrooms, civic and conference spaces, average illuminance levels in the 35 to 55 Foot-candle range tend to be common. When visual tasks are a critical component of the lighting design program, a designer is advised to consult more technical reference material for Illuminance level
recommendations onto specific task surfaces.
The illuminance guidelines above are a gross simplification of a topic that encompasses much study and engineering. For our basic understanding and ability to visualize, these numbers will suffice.
It is important to realize that whole room illuminance levels are just
reference targets off which to build. The hope is that all of the specific task and accent lighting that gets added to the space will inter-reflect to create this glow. Our design procedure in not to create an ambient light level first, and add accent or task affects later.
We define lighting goals for specific surfaces and objects for task and
accent first and then assess the effect. Only after we have done this, do we design lighting intended to increase ambient light levels or perceived brightness.
As illuminance level targets find their way onto the Light Map, designers
will find their lighting design fall into place much easier.