Benefits Of Daylight
Daylight in interior spaces has multiple benefits. Daylighted environments provide a nnection to the outdoors, are healthier for occupants and have the potential to save energy. Research has shown that children learn better1, retail stores sell more product2, and office workers are more productive3 4 in daylighted environments. Since daylight also helps to regulate our circadian cycle5, introducing daylight into interior spaces is a top priority. Daylight is a natural resource that is more efficient than electric light and should be utilized to its fullest potential.
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Maximize Daylight Potential
Building orientation, views, side and top lighting, shading devices, and selective glazing are all critical to maximizing daylight potential. All of the following recommendations are for the northern hemisphere. In the southern hemisphere, recommendations regarding north and south orientations are reversed. Also, interior spaces should have high ceilings and light reflective surfaces to allow deep daylight penetration. Provide architectural and manual shading devices for daylight and view windows. In areas of high threat, lightshelves tend to be discouraged because of blast mitigation. These objects can become additional projectiles during a blast.
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Active Daylighting And Physical Modeling
Active daylighting strategies and devices utilize a mechanical component to collect and distribute daylight. Such devices differ from the passive strategies that have previously been discussed which are stationary. The example shown in figure 4-10 turn a series of reflectors as the sun moves throughout the day. These reflectors catch the direct sunlight and redirect it through the skylight.
Such devices add extra initial cost and also pose additional maintenance issues. However, they also can make use of daylight for a longer period of time throughout the day. With tracking devices, effective daylighting can begin earlier in the morning and last later in the day than with stationary skylights. Careful evaluation of the lifecycle cost and the energy savings must be considered.
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Budget Considerations (Lighting Equipment)
There are many economic factors that need to be considered when designing a lighting system. Life cycle costs include initial costs (equipment procurement and installation), energy, and maintenance costs. Additional issues involve the impact of lighting on productivity. These costs are currently not represented in the life cycle cost analysis.
Estimate equipment quantity and unit pricing for luminaires, lamps, ballasts and controls. Also estimate the labor cost. Do not use a percentage of initial costs because this can be misleading. For example, installing direct/indirect linear fluorescent pendants may be less labor since they require only one point of electrical connection, versus individual recessed lay-in luminaires.
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Maintenance costs, Energy Models
Life and reliability of the lighting equipment are inherent in maintenance costs. In addition, replacement procurement and installation costs are factored into the formula. Group re-lamping is always cost effective over spot re-lamping. Lamps that are reliable and need replacement every several years (versus months) need to be specified. In addition, specify compatible equipment. For example, when lighting is controlled with occupancy sensors, the ballast and lamp need to respond to this type of frequent control. Lamps that work well with occupancy sensors are rapid start and programmed start fluorescent and induction lamps. Instant start fluorescent and HID lamps are not compatible with occupancy sensors.
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