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Energy Efficient Skylights

Skylights are some of the hardest-working windows around. They can add a wash of natural light to your home, open up a dim corridor, or boost the luxury of your master bath without sacrificing privacy. And they even reduce some of the need for artificial lighting, which adds up to a small savings on your energy bill.

Unfortunately, not all skylights are designed the same—particularly when it comes to their energy efficiency. According to the Department of Energy, in fact, inefficient skylights increase heating and cooling consumption by upwards of 40 percent. It makes sense when you think about it, since they’re essentially a hole cut in the roof, your home’s number one defense against the weather.

That doesn’t mean you can get a skylight with great efficiency ratings though. It just means, like any windows replacement project, you’ll ultimately save money if you learn a little bit about what makes them energy efficient ahead of time. Below, you’ll find a guide to picking out the best skylight for your space.

skylight in bath

Table of Contents

Know What You Want

Skylights offset the cost of lighting during the day. And they can provide a source of ventilation for hot, moist air, like steam from a shower, or heat radiating from an oven. In fact, when placed thoughtfully, they even add solar heat to a chilly room.

To decide what kind of skylight you want, it’s helpful to understand what your space needs. Do you want your skylight to help with ventilation? A retractable vented skylight with weather sensors might be your best bet. Or are you looking mainly for light and design? An angled skylight positioned on a north-facing roof may serve you best. That way, you can avoid excess heat while taking advantage of the extra sunlight.

Or do you want to take advantage of solar heat gain as well to help with winter heating? Positioning the skylight on a south-facing slope will add the most heat to your home. Either way, getting clear about your needs should be your first priority.

Orientation Plays a Role in Solar Heat Gain

As mentioned earlier, the position of your skylight makes a big difference on your overall heat gain. If you live in a warmer climate, where air conditioning makes up the majority of your energy expenses, look for a north-facing slope. That will ensure that the lowest amount of passive solar heat enters your home.

On the other hand, if you live in a very cold area, a south-facing window may offset some of your heating costs in the winter. Be aware, however, that it will also add solar heat in the summer, so you should really only use this technique in a climate with relatively few hot days.

East- and west-facing skylights generally make a more neutral choice. They may add some heat, but certainly not as much as those facing south.

Larger Skylights Consume More Energy Than Smaller Ones

When selecting your skylight, you’ll need to consider its size and the size of room. The Department of Energy recommends that you limit the size of your skylight to no more than five percent of the room’s total area if the room already has many windows installed.

If the room contains few or no windows, you may go as high as fifteen percent. However, keep in mind that the larger the skylight, the more your home will be subject to heat loss and gain that can drive up energy bills.

skylight on roof

The Slope Plays a Part, Too

Angled skylights tend to deflect summer heat. The sharper the angle of your skylight, however, the more effectively it will deter solar heat gain. A low sloped or flat skylight, on the other hand, captures more sunlight and heat during the summer months, when the sun sits more directly overhead. And that can make the room uncomfortable during the warmer months.

To find the ideal angle for your skylight, add 5 to 15 degrees to your home’s geographic latitude. For instance, if you live in Austin, Texas, which has a 30 degree latitude, the ideal slope measures somewhere between 35 and 45 degrees.

Tubular Skylights Add Natural Light With Better Insulation

If you’re not particularly married to the design of a traditional skylight, a solar tube may be your best bet. Solar tubes—also known as tubular skylights—have a circular shape with a domed cap that harvests sunlight from various angles and reflects it back into your home. That helps keep the temperature regulated in the room below, as there’s less roof surface exposed. That also makes them easier to install, since they won’t have as big of an architectural impact on your roof.

The effect winds up feeling like a recessed light, except it’s powered completely by the sun. Many homeowners even place them in rows across a hallway or kitchen island, very similar to artificial lighting.

Skylight Shades Drastically Reduce Heat Gain

Skylight shades, screens, and blinds block excess solar heat on warmer days, making them a great adjustable option for homes that experience a wide variety of temperatures. Many are automated, so you can operate them with a remote control from the floor below. No scary trips up the ladder for you!

Like any window, you’ll also need to make sure the glazing has the right energy efficiency ratings for your area, as well. Make sure to review the regional criteria for energy performance before you make your final purchase. That way, you can have all the lighting benefits of a new skylight while staying comfortable in your home year-round!

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