Energy 101: Daylighting

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Daylighting—the use of windows or skylights for natural lighting and temperature regulation—is one building strategy that can save money for homeowners and businesses. Highly efficient, strategically placed windows maximize the use of natural daylight in a building, lowering the need for artificial lighting without causing heating or cooling problems.
Energy Department Video

ANNOUNCER:  OK, so we all know that windows can provide a great view, right?  But if they’re placed in the right locations, they can also save you money on your utility bill, and they can help keep you more comfortable at home or work.

It’s called daylighting, and it takes a simple concept to a new level.  Daylighting combines lots of things – everything from the type of window, window placement and interior design – to control how sunlight comes in.  They all work to maximize benefits from natural sunlight.

Check this out.  Windows that face south are best in the U.S.  They let in the most light in the winter months, but little direct sun during the summer, keeping the inside cooler.  North-facing windows are also good for daylighting.  They let in even natural light with little glare and little summer heat.

Windows that face east and west don’t work nearly as well for daylighting.  They do provide lots of light in the morning and afternoon, but it often comes with lots of glare and excess heat during the summer months.

Have a look at this energy-efficient office building.  The windows team up with skylights to provide most of the light you need.  Notice the light color of the ceiling.  It reflects and enhances the daylight so that it fills the room.  And what about all the overhead lights?  Most of the time, you don’t need them.

To account for glare, this office building placed hoods outside around the windows.  The hoods also cut down on summer heat, keeping the office cooler and more comfortable.

On the inside, louvers or tinting reduce glare and also direct light to reflective surfaces inside, allowing plenty of natural light to come in to work areas.

One big help to daylighting is the window technologies available today.  Windows are now way more energy efficient.  They insulate while still letting the light you want in.

And have a look at this.  It’s an electrochromic window.  This special window changes with the brightness of the sunlight outside.  As the sun tracks across the sky, it darkens to keep excess heat out.  It’s like giant polarized sunglasses.

Daylighting can have a positive effect.  Studies have shown that with good daylighting at the office, productivity goes up and absenteeism goes down, and that’s good for the bottom line.

Natural lighting and heating means you use less electricity and lower you utility bill.  And the more natural lighting, the more money you can save.