Friday, September 11, 2009

Quick TIPS on energy saving: Daylight

What is Day Lighting?
Day lighting is the controlled admission of natural light into a space through windows to reduce or eliminate the need for electric lighting. Today’s highly energy-efficient windows, as well as advances in lighting design and technology, allow efficient use of windows to reduce the need for artificial lighting during daylight hours without causing heating or cooling problems.

Why Use Day Lighting?
Day lighting has been shown to save from $0.05 to $0.20 per square foot annually. The energy savings from reduced electric lighting through the use of day lighting strategies can directly reduce building cooling energy usage an additional 10 to 20 percent. buildings can lead to annual savings of 35-60% on lighting energy.

The U.S. Department of Energy estimates that electronically tintable window systems are capable of providing up to:
40% savings on energy bills
20% savings on operating costs
24% reduction in peak demand
25% decrease in the size of HVAC systems

Who Uses Day Lighting?
Hotels and resorts, offices, residential apartments, hospital and nursing home, art galleries, museum, libraries, religious facilities, aviation facilities, high-tech or image buildings, atriums and overhead daylight openings.

In the summer, day lighting keeps your house cooler as the heat is kept outside. In winter, the heat from objects that are heated by either sunlight or inside heat sources is bounced back into the home, a process which keeps the entire home warmer.

Where and When to Use Day Lighting?
Solar powered smart window, because of their low DC voltage and power consumption, and the obvious complementary relationship between the amount of sunlight available and the level of tinting required to modulate it.

Pluses: Energy saving, increased user productivity, reduced emission, reduction in cooling up to 32 % annually and heating loads up to 39%, reduced fading due to UV rays, reduce escaped or wasted energy, block glare.
Minuses: The cost of electrochromic windows can be from 2 to 3 times that of a standard window. These costs are expected to decrease significantly when manufacturing techniques have improved and quantities have increased. Liquid crystal glazing adds about $90 per square foot to the glazing. Electrochromic films require an electrical hookup that is not required for other types of solar-control window films and therefore requires unconventional wiring at windows and may require coordination of electrical and carpentry trades.

Whole Building Design Guide
New York Real Estate Journal
Sage Electrochromics, Inc.
Efficient Windows Collaborative

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