Skylights are known for being energy-efficient roofing solutions that reduce power consumption and energy bills, making them an ideal choice for spaces that require constant lighting as well as cooling or heating around the clock, depending on the climate.
Skylight energy efficiency proves most useful in places like shopping malls, airports, hospitals, warehouses, and factories, among other public, commercial, or industrial spaces where lighting and temperature control account for a large proportion of energy consumption.
So, how do skylights reduce electricity bills? How do they save energy? Continue reading this guide to learn about the features and properties that help skylights lower energy use and discover more valuable information about their thermally efficient performance.
What Makes a Skylight Energy Efficient? Features & Properties
A lot of work goes into making skylights energy efficient, from the initial planning of their shape and orientation to the manufacturing process. In other words, skylights do not simply happen to be energy efficient. Their design incorporates various features and considerations that help optimise energy use and improve overall performance.
So, why are skylights energy-efficient? Here are some of the technical features and properties of energy-efficient skylights:
1. Low-E Glazing
If you are looking into various skylight materials or exploring skylight installation, you may have already come across the term “Low-E glazing,” which stands for Low-Emissivity Glazing.
In this context, glazing is the transparent material used in skylights that lets natural light into your interior space. When this material, typically glass, is described as low-emissivity, it means that its surface emits less radiant heat, helping provide better temperature control.
To make the glazing low-emissivity, it is designed with a very thin, almost invisible coating that helps reflect indoor heat back into the building during winter, instead of allowing it to escape. Low-E skylights also help reduce the amount of solar heat entering from outside during summer.
This way, your indoor place remains cool in the summer and warm in winter, significantly reducing reliance on HVAC systems for heating and cooling. This first feature is very important in designing energy-efficient skylights.
2. U-Value
“U-Value” stands for “thermal transmittance” and it measures how much heat passes through the skylight. Unlike low-E glazing, U-value is not a singular feature but rather an overall measure of the skylight’s thermal performance, taking into account various factors, such as:
- Glass/glazing: The material type, its thickness, and the application of the low-e coatings all impact the skylight’s U-value.
- Number of panes: Glazing provides better insulation when the panes are doubled or tripled, especially when there is insulating gas between them.
- Frame: The material and design of the skylight frame also affect heat transfer.
- Installation: Poor installation can negatively impact thermal performance.
That being said, a skylight with a low U-Value provides better insulation and greater energy efficiency, while a skylight with a high U-value does the opposite. But how does U-value make skylight energy efficiency possible?
With the proper glazing, coatings, installation, and more, the U-value is reduced, meaning that the skylight limits heat transfer through its panes. The end result? Less heat loss in winter and heat gain in summer, minimising the workload on heating and cooling systems and improving energy efficiency.
3. SHGC
SHGC (Solar Heat Gain Coefficient) measures how much solar heat enters a building through the skylight. A lower SHGC limits solar heat gain, making it useful in hot climates like the UAE, while a higher SHGC allows more solar heat to enter, which is beneficial in colder climates by helping warm the space. In both cases, the proper SHGC rate is crucial to skylight energy efficiency.
It is important to distinguish between U-value and SHGC; the first measures heat transfer through the skylight, while the latter measures solar heat entering through it. Notably, SHGC is impacted by a variety of aspects, including but not limited to:
- Type of Glazing: Different skylight materials absorb, reflect, and transmit varying amounts of solar radiation.
- Low-E Coatings: Some low-emissivity coatings can minimise the amount of solar heat passing through the skylight.
- Tinting: Tinted glass can transmit less solar radiation through the skylight, depending on its shade and formula.
- Design & Orientation: The skylight design, configuration, and orientation have a direct impact on the amount of solar heat that can enter through it, significantly affecting the SHGC measurement.
So, how does the SHGC rate contribute to skylight energy savings? The proper SHGC rate minimises the need for cooling and heating systems to work continuously to control indoor temperature and keep it at a comfortable level. Therefore, energy-efficient skylights reduce energy bills through a combination of features that achieve the suitable SHGC levels.
4. Double & Triple Glazing
Skylight glazing can comprise a single pane, or it can be double glazed or triple glazed. Meaning? A double-glazed skylight has two layers or panes of glass with a sealed space between them, which can be filled with an insulating gas for better insulation. A triple-glazed skylight has three panes of glass and two sealed spaces between them.
How do skylights save energy, then? Double and triple panes are one of the most effective ways to improve the skylight’s thermal performance and energy-saving capacity. What these additional panes do is create greater resistance to heat transfer, keeping your place cool in summer and warm in winter by reducing heat gain and loss.
As a result, such double- and triple-glazed energy-efficient skylights lower HVAC demands and help reduce energy bills.
5. Visible Transmittance (VT)
This aspect is part of the reason why skylights are energy-efficient. Visible transmittance means the percentage of visible light that passes through the skylight’s glazing to illuminate the indoors, and it is determined by laboratory testing of the glazing. The higher the transmittance, the more visible light passes through, so brighter the space is.
But how does a high VT help skylights reduce electricity bills?
Skylights with good visible transmittance bring more natural daylight indoors, meaning that you do not need to rely on artificial lighting as much during the day. This is significant in big places that need constant lighting and a pleasant environment, including hospitals, schools, public buildings, shopping centres, and others.
Now that you know how and why skylights are energy-efficient, it is important to understand how they reduce energy consumption. So, how do skylights save energy?
How Do Skylights Save Energy?
How do skylights reduce energy costs? How do the above energy-saving properties and features translate into lowered electricity bills and reduced energy consumption? Now that you know what makes an energy-efficient skylight, here is exactly how it saves you energy:
1) Natural Daylight
A skylight’s most prominent function is providing natural lighting. No matter the type of skylight, its shape, or material—it is designed to allow natural daylight to fill in the place. And since skylights are positioned overhead, they distribute light deeply into interiors, illuminating the area more efficiently compared to vertical windows.
As such, skylights with a high visible transmittance play a major role in reducing reliance on artificial lighting. There is no need to switch to electrical lighting when the entire place basks in sunlight with no hues or harsh glare. As a result, skylights reduce electricity bills and minimise operational costs.
2) Reduced Cooling Energy
Skylights can be designed to allow an abundance of natural light to come inside while minimising solar heat gain, which is a major advantage in hot climates like the UAE and other GCC countries. Such skylights integrate proper glazing, suitable SHGC rates, and insulation mechanisms like double- or triple glazing and insulating gas.
With the right features and mechanisms, skylights do not let much heat pass through them. Consequently, HVAC systems do not need to work excessively to keep the place cool, reducing energy consumption and bill amounts.
3) Passive Solar Heating
Skylight energy efficiency is not limited to daylight and cooling performance only, as it plays an important role in heating as well. Skylights installed in colder locations can let sunlight inside, which provides useful heat to the interior. With the proper insulation and SHGC, these skylights help maintain a warm and comfortable temperature through passive solar heating.
How does this contribute to skylight energy savings?
Instead of relying entirely on heating systems, skylights can help warm the space by harnessing the sun’s natural heat and energy, reducing energy consumption and heating costs.
4) Natural Ventilation
You may still be thinking about how to make skylights more energy-efficient. In this case, you can choose to install an operable skylight (also known as a retractable skylight) to further elevate your skylight energy savings.
Installing an openable skylight allows you to open it either manually or electronically to let stagnant air leave the place and let fresh air in. This creates a natural airflow, ventilating your space thoroughly while reducing dependence on HVAC systems and energy costs.
Explore now: What is an Operable Skylight? Advantages and Reasons to Install One
FAQs about Skylight Energy Efficiency
Here are some further insights about skylights and their energy efficiency:
1- Are skylights suitable for every climate?
Yes, skylights are suitable for hot and cold climates, as they are designed and manufactured to suit climate conditions like excessive heat, strong rain, potential falling debris, and other factors. Skylights also integrate various features that help maintain suitable indoor temperatures, taking into account external weather conditions.
2- Can skylights cause a room to become too hot?
Yes. Skylight shape, material, size, and position are all factors that determine how well it can keep the room warm or cool. So a poorly selected or positioned skylight can surely make a room too hot.
3- Do skylights require regular maintenance to remain energy efficient?
Yes, regular maintenance is essential for skylight energy efficiency, which can include cleaning glazing material, inspecting frames and seals, and checking for cracks, leaks, or other signs of damage.
4- Are skylights a good investment for commercial buildings?
Yes, installing a skylight is a great investment for commercial buildings, especially if you want to save costs in the long term. While the upfront price can be high, skylights reduce energy costs for ventilation, lighting, cooling, and heating, proving to be energy-efficient and cost-efficient in the long run.
5- Are skylights more energy-efficient than windows?
Skylights can be more energy-efficient than windows in certain applications, particularly when they are designed and positioned to maximise daylight distribution.
Energy-Efficient Skylights from Almamary
Almamary for skylights is a trusted manufacturer and installer of commercial and residential skylights in the MENA region. With decades worth of experience, Almamary’s team designs, builds, and installs energy-efficient skylights to help reduce energy costs while also allowing natural light in.
Almamary’s skylights include structural skylights, coloured skylights, operable skylights, and much more. Whether made of glass or polycarbonate, shaped like a pyramid or a dome, Almamary’s skylights will surely elevate your place, maintain comfortable temperatures, and reduce energy consumption.
Consult our team to begin.
Learn more: Coloured Skylights: Key Features, Installation, and Design Ideas
Further insights: Commercial Skylights: How to Choose the Best One?
More details: Glass Skylights: Benefits, Types, and Installation Guide