What is in this article?:
- Light Moves
- Glazing in the balance sheet
Integrating daylight into school design from the start.
It is satisfying to visit a space with sufficient daylight and observe that no one has seen the need to turn on any lights. (Harold G. Fearn Elementary School, Aurora, Ill.)
Numerous studies have demonstrated the benefits of daylight on the learning environment. Enhanced student performance and mood, increased teacher and student attendance, reduced energy costs, as well as a positive effect on the environment are some of the improvements seen in school buildings that use well-planned daylighting concepts.
Looking at the list of benefits, one might be surprised that optimizing daylighting in schools often is regarded as a design preference instead of a basic responsibility. Recognizing the importance of daylighting, Title 24, California's energy code, was revised recently to include mandatory lighting control requirements wherever rooms have windows. Title 24 has served as a blueprint for other states.
Designing with daylight
It is crucial to consider daylighting from the beginning of the project — as early as during site analysis and planning. A building's site, orientation and massing should be viewed through the lens of optimizing daylight opportunity. Reflective surfaces, and western or eastern orientations that can result in glare and obstructions to sunlight from tall buildings or trees, should play a significant role in determining building placement, size, proportion and position.
However, bringing in light is only the first step. Controlling and harnessing it is the greater challenge. An exterior horizontal surface can receive as many as 10,000 footcandles on a sunny day — more than 200 times the light needed for most educational tasks. Directing daylight into a space without managing it can have an effect opposite of what is intended. Too much direct light and glare have a negative effect on comfort and productivity. Heat gain, another disadvantage of inadequately controlled sunlight, is limited by keeping direct radiation away from a building's skin.
Exterior sun control is therefore often preferable to interior control methods. The layout of indoor spaces, the color, texture and reflectivity of interior surfaces, interior shading devices and architectural elements such as light shelves are vital components of a well-performing building.
Coordination of daylight with electrical lighting is another central factor in designing healthful, highly efficient buildings. If daylighting is to reduce energy loads rather than increase them, artificial lighting must be turned off or dimmed consistently when ample daylight is available. This condition is known as daylight autonomy. Efficient light fixtures, zoned lighting controls, occupancy sensing and user-friendly, fine-stepped or continually dimming technologies enable additional energy savings.