Energy-Efficient Skylights: What to Know

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.

What Helps Make a Skylight Energy Efficient?

Skylights absolutely have the potential to be energy-efficient. Skylights offset the cost of lighting during the day. They can also 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.

However, if your skylight is not at least double-glazed and does not take advantage of options like tinted glass, insulated glass, or roller shades, then you may find it’s letting too much heat into your home.

Installing a Skylight: Making an Energy-Efficient Choice

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.
• 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.
• 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.

Skylight Orientation Plays a Role in Solar Heat Gain

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.

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.

If you live in a temperate climate or an area with both extreme heat and cold, then an east- or west-facing skylight will generally make for a neutral choice. They may add some heat, but certainly not as much as those facing south.

Consider Skylight Slope for Best Results

The sharper the angle of your skylight, 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.

The Best Glass for Skylights

Like any window, you’ll also need to make sure the glazing has the right energy-efficiency ratings for your area. Make sure to review the regional criteria for energy performance before you make your final purchase.

You can also take our glass type quiz if you need help deciding on glazing and any additional coatings for your skylight. That way, you can have all the lighting benefits of a new skylight while staying comfortable in your home year-round!

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.

How to Make an Existing Skylight Energy-Efficient

If you already have a skylight installed and are not going to be replacing the glass or frame soon, then there is an easy-to-find solution: blinds and shades.

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.