Most of us would welcome more natural light into our homes. For one thing, it can reduce electricity use by lessening the need to keep lightbulbs running. A brighter home also helps improve one’s mood, and sunlight even provides physical health benefits by increasing the body’s Vitamin D intake. While windows let sunlight into most homes during the day, for some it might not be enough. In many cases, certain interior rooms may not have any windows at all. Thus, getting more natural light from above can be a solution for making spaces brighter, completely changing the environment in a room.
That’s where solar tubes and skylights come in. While similar in purpose – that is, to provide more daylight into a room – these roof and ceiling fixtures bring sunlight into the home in very different ways. Both have varying functions and characteristics, with accompanying pros and cons – everything from cost and energy efficiency to light control and aesthetics – and different homes may benefit from one more than the other.
How Do Solar Tubes and Skylights Work?
True to their name, solar tubes (also known as sun tunnels, sun tubes, or light tubes) are essentially tubes that tunnel sunlight into the home. Instead of providing a direct line of sight to the sky, a solar tube will capture light on the roof and disperse it into the room below. That natural light is collected on the roof by a polycarbonate or acrylic dome top, and a series of mirrors then reflect it down to the bottom of a sheet metal tube. At the bottom-end is a diffuser that looks much like a light fixture in the ceiling – but, instead of a lightbulb, natural light is dispersed throughout the room. A tube can range in size, but they are generally on the small side – about ten inches in diameter or more.
Skylights, at their most basic level, are glass windows facing the sky. They let rays of light directly into the home without the need for any reflections, usually through a rectangular pane of glass or other clear material that is visible in the ceiling. The sunlight is not diffused like with a solar tube, but is instead directly shone onto the floor area below. The resulting shape and size of the light’s shine will be directly based on the shape and size of the skylight – while shifting across the room like a slow-moving spotlight, based on the sun’s position.
Comparing Skylights and Solar Tubes
Below is a comparison of solar tubes and skylights based on various factors. The differences and pros and cons of each can serve as a guide for anyone considering which of these fixtures to install in their home.
Ease and Practicality
For an existing home, a solar tube is not too difficult to install. There are not many special considerations that need to be taken, although they may not be suitable for a roof with a very steep pitch. However, most roofs with a moderate pitch can support one, and different products and tunnel designs are recommended based on how the roof and ceiling are situated. They can also be installed even when there is attic space between the roof and the room receiving the light. Solar tube installation should generally be performed by contractors, but it is rather quick with setup, flashing, and finishing taking only a couple of hours or half a day’s work.
While skylight sizes vary, they are generally much bigger than a solar tube. A significant amount of carpentry work is required, with generally at least one rafter removed and all others needing reinforcement. Flashing and finishing around the skylight is also vital, and solid, professional work is needed to prevent any potential leaks. In general, they can be more of a hassle to install.
Advantage: Solar Tubes
Material and Installation Costs
Since adding a solar tube requires a relatively low-impact installation, with no major effects on the ceiling’s drywall or the roof’s framing, the cost of getting one put in is fairly low. The cost of a tube itself can vary widely based in part on potential add-ons; for example, some products may have an LED kit built into the diffuser so it can still supply light at night. In the end, the typical cost of getting solar tubes is less than $1,000, including materials and a professional installation. An added benefit is that many models are Energy Star rated, and therefore eligible for a 26% tax credit.
The price of a skylight can also vary, in part based on add-ons such as UV-protection coatings. The installation cost will be largely based on the size and condition of the roof, as well as the roofing material, but it is usually more intensive and costly than for a solar tube. The total cost for materials and installation can run anywhere from a few hundred dollars to two grand.
Advantage: Solar Tubes
Warm Weather Energy Efficiency
Solar tubes are especially advantageous in spaces that lack wall windows and do not get much natural daylight, as they will disperse natural light throughout an interior space. During a sunny day, they can produce as much light as multiple standard light bulbs, lessening the need for electricity. Solar tubes also block heat energy from getting in, and so they can do their job without raising the cost of air conditioning.
Skylights, on the other hand, provide more concentrated light that can also heat up the home. Unless certain measures or coatings are applied, heat energy is shone through as well. This can raise air conditioning costs during the summer months, when daylight is at its longest. This is especially relevant in warmer climate areas.
Advantage: Solar Tubes
Cold Weather Energy Efficiency
While the lack of heat supplied to a room can be nice in the summer, this is less of an advantage during colder months. The diffusion of free sunlight for daylighting is still useful in the winter, though those well-lit hours are shorter.
The passive solar heating from a skylight can be a major advantage in the winter. The effects will be especially beneficial if a home is designed with passive heat gain in mind. Sunlight can shine from the low winter sun through a strategically-located, southern-facing skylight that maximizes its effect to lower the cost of heating. In colder climate areas, this can make a huge difference for a home.
Solar tubes control the type of light energy that gets through. Specifically, the acrylic dome on the roof generally blocks UV rays before they get into the tube itself. This means that any light dispersed throughout the home will not cause sunburns or other adverse effects connected to harmful UV rays.
Skylights do not usually block UV light at the source in the way that solar tubes do. While a filter coating can be added to reduce the penetration, there will still be some that gets through. In addition to the potential long-term health effects, UV rays can cause furniture and decor to fade over time
Advantage: Solar Tubes
Since the output looks similar to a normal light fixture, and the rooftop dome being rather small, one could be forgiven for not noticing a solar tube is even there. Solar tubes are subtle in that way, which some may appreciate. Since the light they disperse is natural, this can provide a pleasing aura to a space. What solar tubes lack, however, is a view to the outside. So even if the light provided is natural, there is no added benefit of a pleasant view.
As an alternative, skylights, of course, allow one to see directly outside and appreciate what’s above and around them. During the day, that can mean enjoying the sky, trees, and any birds flying overhead. Even at night, stargazers have something to enjoy. Moreover, some may also find that a skylight makes the room feel a bit bigger.
Even though the diffuser of a solar tube can resemble a lightbulb fixture, there is no on/off switch. Once a tube is installed, the sun tunnels down and will consistently spread light each day. It would be difficult to block or control that lighting, if needed.
A skylight may be customized with shades that can alternately block the sunlight or let it through. Some skylights can even be vented, allowing one to open and close it like a window.
Cleaning and Maintenance
Since the top of a solar tube is domed, it is difficult for debris to stick to one. In general, there is very little cleaning or maintenance needed as it is rare that anything – other than snow or other short-term accumulations – would obstruct the sunlight from getting in. While solar tubes have a low propensity to leak, water condensation may develop on the inside of a tube, especially in high-humidity areas or spaces, such as laundry rooms. This can be prevented by wrapping the tunnel with R-15 or R-19 insulation, while some models even offer a condensation release. Ignoring any condensation can lead to mold problems or long-term damage of the solar tube.
Skylights are much more likely to have debris, from bird poop to leaves and everything in between. This can not only block the sunlight, but it can also make the skylights much less pleasant to look through. Debris that collects over prolonged periods of time can also increase the likelihood of leaks, which are relatively common with skylights. For this reason, they may require a fair amount of maintenance and cleaning. Skylights also accumulate water condensation, generally inside the surface; prevention in this case usually requires treating the air with a dehumidifier.
Advantage: Solar Tubes
Should You Get Solar Tubes or Skylights?
Solar tubes and skylights are natural lighting options with unique qualities, which may bring varying benefits depending on a home’s condition, location, and a person’s preferences. Let’s say, for example, Charlie wants more light in his house but has a low budget, a small roof, and lives in a moderate climate and in an area without much nature or beauty to admire in the sky. Michelle, on the other hand, has plenty of money saved for home improvements for her big house in the cold north, which is situated in an area with beautiful scenery and birds flying all around.
When it comes to choosing whether to install a solar tube or skylights, Charlie and Michelle can use these points as a guide.
To recap, solar tubes’ benefits over skylights usually include:
- Easier and more practical installation
- Lower cost for parts and installation
- Energy efficiency in warmer weather
- A better quality of light, without UV
- Less cleaning and maintenance required
While skylights have a few potential benefits of their own:
- Heat gains and energy efficiency in colder weather
- Better aesthetics
- More control over the light output
Based on these factors, for Charlie, a solar tube might be the way to go. The installation is affordable, and since he lives in the US he can take advantage of the tax credit for an Energy Star model. The lack of heat gain will create both advantages and disadvantages, depending on the season. The low maintenance will also help keep costs low and life a little bit easier. And, since there is not much to see in the sky anyway, the lack of scenery compared to a skylight is no huge loss for him.
Michelle, alternatively, may prefer the more expensive skylights, as she’s been looking to fundamentally change the look of her interior living spaces while also increasing her home’s resale value. She can have the skylights situated so they face the southern sun, helping her warm her house with passive solar heating in the winter. Michelle may even choose to get shades installed to block the sun when the weather gets warmer in the summer. Best of all, she can have an even better view of the beauty surrounding her home.
Of course, these considerations and their relevance will vary widely for different people and their personal situations. But for anyone considering which is right for their home, the factors laid out above may help lead them to the answer. In the end, whether through a solar tube or skylight, letting more light shine down from above can help transform a home for the better.