This post is going to cover the topic of energy optimisation associated with rooflights. How environment-friendly and energy-saving are they exactly and are they a good investment?

There is a common misconception that skylights can ruin the air conditioning and heating of your home. The answer to that question will vary depending on one’s particular goals and wants. So, continue to read if you need to know about skylights and energy optimisation.

Key Takeaways on Energy Efficiency of Skylight Installation

  • Pitched and flat roof skylights offer several benefits such as increased sunlight and excess moisture removal
  • The position, tint, coating, ENERGY status, and other factors affect how green your new skylight will be
  • Rooflights also have their issues and you'll need to consider them before roof installation
  • Poor installation can ruin even the most energy-efficient skylight, so don't underestimate it

How are Skylights Energy Efficient? What are the Benefits?

A great deal of benefits can be obtained through skylights. They remove excess moisture, heat, and odours, as well as indoor pollutants. When there is plenty of sun during the cold months, skylights can decrease the need for air-conditioning. That's great for the environment as it requires less money on energy bills. 

In some instances, they can eliminate the need for artificial lighting. On that note, they can reduce the overall number of bulbs you need and positively impact your lighting bill in the long term. All things considered, skylights can help you save a lot of money on a yearly basis.

What to Consider for Optimal Energy Efficiency

To ensure that you get the best rooflight, you should check out certain specifications. For example, you should look at the solar heat gain coefficient (SHGC), which tells you how much solar energy gets converted to heat via your skylight, the U-factor, and the energy performance ratings known as ENERGY STAR status.

The U-factor is a calculation that determines the rate of heat loss, i.e. how much heat gets lost through the building materials. This will give you an idea of how energy efficient your unit is and help you decide the right skylight size and type for your place. The number is expressed as watts per square metre per Kelvin, or W/m²K and reflects the thermal resistance of the frame and the glazing, their thermal conductivity and thickness.

The coating and tint play a huge role as well, so choose wisely and don’t try to skimp on these things. You should also ensure the optimal slope for the rooflight depending on the geographical latitude. This will affect how much light (and heat) enters your home.

Furthermore, the position of the skylight is crucial for how much energy it takes to cool, light and heat your home. If you have yet to choose where to place your new windows, now is the time to think about the best position for them. You have to take into account the position of the sun rather than your personal preferences.

If you are looking to receive the most sunlight throughout the day, you need to make sure your skylights are south-facing. This will definitely take a toll on energy performance during hot summer days but it will be great for cold winter days. South-facing skylights provide the greatest potential for passive solar heat gain in winter; however, they can also give unwanted heat gain in summer. West-facing skylights provide afternoon sun.

In some cases, you can achieve optimal efficiency by installing your rooflights underneath leafy trees facing south. and lastly, skylights should take up 3-5% of the floor area of your room. Read our detailed skylight installation guide for more information.

Potential Skylight Issues like Leaks, Solar Heat Gain, and Heat Loss

Although skylights bring a whole host of benefits, they can cause issues as well. You should be aware of the problems you might encounter over time after you install skylights on your roof. This will help you select the best and most optimal piece for your needs.

Heat gain. Solar heat in the summer is associated with rooflights and big windows. To minimise that, you need to invest in quality units that use low-emissivity coatings (Low-E) and incorporate argon gas between the insulated panes. Velux skylights come with these features. It's recommended you pick a translucent insulation material. Check out our post on skylight insulation for more information on this.

Loss of heat. Even if you invest in the best coatings for your roof lights, sometimes they can let heat escape from the room in which they are installed. This will affect the temperature indoors and your energy costs overall. 

Glare. Depending on the position of your skylights, you may get a nasty glare on your computers and TV screens when the sun is out. A proper position is essential. North-facing skylights offer the least amount of glare.

Fading. Big skylights allow lots of sunlight and heat which can hit your furniture causing it to fade over time.

Leaks. Leaks are not uncommon with skylights, especially when the units are not installed properly on your roof. So you want to keep that in mind.

These issues should not be overlooked if you are planning to get skylights. If you’re going to make a huge hole in your roof, it is not a wise idea to cut corners on the pieces you purchase.

So are Larger Skylights a Good or Bad Idea in Terms of Energy Consumption, Ventilation and Cold Climate?

While skylights can be a great addition to any home, you should weigh down the pros and cons before you decide to have one.

Skylights bring natural light, opening the space and uplifting the mood. This also helps keep the room warm during winter. Plus, it enhances the curb appeal of your house in case you are looking to sell it or just for the sake of aesthetics.

What is more, skylights reduce your energy bills and improve indoor air quality. This is because they ensure good ventilation by banishing hot air that naturally accumulates around the ceiling. It applies to ventilating skylights to a greater extent. They can be amazing in cold weather. However, that works only if you live in an area that receives lots of sunlight throughout the year. If you happen to live in a shady area, you will not benefit from skylights. There is probably no point in making such a purchase. Your location plays a key factor.

Besides, not everybody is fond of roof windows or skylights. Some people don’t like the way they look. Plus, if you get a cheap skylight, you will not reap these benefits. And even if you buy the most expensive piece, unless it’s installed properly, you won’t enjoy the outcome. Last but not least, a purchase of this kind might blow your budget.

FAQ on Skylights and Energy Efficiency

Do skylights lose heat?

Yes, skylights can lose heat energy in winter and cool air during summer. The good news is that there are ways to minimise nighttime heat loss in winter by choosing the most quality products and select the glazing type with care.

When should you replace old windows?

The majority of windows have a lifespan of 15-20 years. After this time, the seals become compromised making your home vulnerable to water seepage and drafts. When it comes to skylights, they last 8-15 years, which means, roughly speaking, you should replace them every 10 years.

What windows should you use when trying to build a Passive House?

Skylights come in a variety of shapes. If you want to have a Passive House, you should get insulated thermal windows, opt for extra glazing, and consider automatic shades. The units should be properly installed on your roof.

Skylights add natural light and if you take a good pick, you won't have to worry about the heat in summer

As you can see, the type, the position and the size of the skylight greatly affects solar heat gain in the summer and other aspects. This should be something you consider ahead of time. Hopefully, this post will give you some insight into the energy efficiency potentials of skylights and the prospective issues you could run into when dealing with windows of this kind.

If you still aren't sure which unit to get, check out what the department of energy recommends. Or else, feel free to consult us and we promise to help you choose the best items for your building.