Title: Reading and Audio-Visual Assignments
Course: WGF 105 DEVELOPMENT > Section: Content

Sub-Title | Electric Lighting Controls
Content
Electric lighting controls are used in lighting design projects to achieve a high quality energy efficient lighting system. Specifying a layered, daylight-integrated lighting and control system gives the occupants control of the lighting while providing appropriate lighting levels, minimizing glare, balancing surface brightness, and enhancing the surrounding architecture.

When electric lighting controls are used properly, energy will be saved and the life of lamps and ballasts can be extended. Lighting controls will help reduce energy by:

- Reducing the amount of power used during the peak demand period by automatically dimming lights or turning them off when they are not needed
- Reducing the number of hours per year that the lights are on
- Reducing internal heat gains by cutting down lighting use, which allows for reduced HVAC system size and a reduction in the building's cooling needs
- Allowing occupants to use controls to lower light levels and save energy

There are other reasons to use electric lighting controls. For example, dimming controls can provide the lighting flexibility which is often required in multi-use rooms or rooms in which projectors are used. Exterior motion detectors and interior occupancy sensors can be used to turn lights on when people (including intruders) are present. Moreover, by tuning an environment for the individual occupant's or group's visibility, comfort and productivity can be improved.
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Content
Lighting controls are cost-effective, especially when one considers long-term life-cycle costs along with initial costs. Lighting controls can add approximately $0.50-$1.00 per square foot initially. Payback periods vary widely by project and are difficult, at best, to predict accurately. That does not take into account the savings from reduced energy use and HVAC reduction.

The easiest way to do an economic analysis of lighting controls is to use an "effective energy charge (EEC)," which is a cost per kWh number derived by dividing the entire electricity bill (in dollars) by the total amount of energy used during that billing period (in kWh). The potential savings per controlled fixture is calculated as follows:

$ Savings per year = ([Wb x HPYb x PFb] — [Wf x HPYf x PFf]) * (EEC) * (1 kWatt/ 1000 Watts)

Where:

- Wb is the baseline watts of the controlled fixture(s)
HPYb is the baseline number of hours per year that the fixture is on
PFb is the baseline power fraction for the fixture or fixtures (use 1 for full power)
Wf is the final watts of the controlled fixture(s) (i.e. after retrofit or redesign)
HPYf is the final number of hours per year that the fixture is on (i.e. after controls are installed that turn the lights off when they are not needed, such as occupancy sensors or centralized controls)
PFf is the final power fraction for the fixture(s) (i.e. if a fixture will be dimmed to an annual average of 50%, use .5. For low dimming levels, the energy usage fraction is slightly higher than the dimming percentage due to ballast losses.)
EEC is the "effective energy charge" in $/kWh.

This method of calculating annual dollar savings is an approximate estimate because is does not allow you to calculate the exact changes in demand charges—demand charges have been wrapped up into the "effective energy charge."

Links/Uploads | Electric Lighting Controls – Whole Building Design Guide http://www.wbdg.org/resources/electriclighting.php Smart Controls – Whole Building Design Guide http://www.wbdg.org/resources/smartcontrols.php#
Attributions | Images and content courtesy of Whole Building Design Guide – National Institute of Building Sciences