One of my good friends has the most stunning ceiling lantern in her kitchen extension – although she freely admits that, on a hot summer’s day, she regrets ever installing it. It makes the whole place uncomfortably hot to pass the time – and that’s before any cooking begins.
With a kitchen remodel on the horizon, I love the idea of fitting Ceiling lanterns As a way to bring more light into my new space and create an attractive focal point – but I’m really worried that doing so will make the space unusable on a hot day.
Before dismissing the idea entirely, I decided to speak to a few experts to get their take on the matter – and I was pleasantly surprised by what they had to say.
Do ceiling lights always cause overheating?
At Andrew Madge, Director Vacuum Glazing UKExplains that, when properly designed and installed, ceiling lights don’t have to be a problem with overheating. “The goal should be a room that feels bright, comfortable and useful all year round. A good ceiling lamp should bring in the sky, not the full force of a heat wave.
“Glass needs the right thought because there’s a big difference between a room full of natural light and one that gets hotter when the sun comes out,” he continues. “You want Daylight without the discomfort, not pretty new Kitchen extension Which looks like a greenhouse with a dining table in mid-July.”
At Edward Stobart, Technical Sales Manager IDSystemsAgreed that overheating should not be something that is simply accepted as part of fitting a lantern to the ceiling. He says the key lies in getting the design right from the start. “Incorporating ceiling lanterns without creating overheating issues requires careful design from the start.”
Good news then, so what are the secrets to a successful ceiling light installation?
Andrew Madge is Managing Director of Gowercroft Joinery and Director of Vacuum Glazing UK, the exclusive UK importer of Landvac Vacuum Glazing. Andrew has been involved with vacuum glazing since 2013, long before it was widely discussed in the UK retrofit market. At Gowercroft Joinery, he helped develop the UK’s first vacuum glazed replacement window range, designed for heritage and retrofit projects, which required a careful balance of traditional appearance and modern performance. Passionate about product development and innovation, Andrew has spent years researching vacuum glazing technology, testing how different products perform and identifying the best solution for the UK market. Andrew is also President of the British Woodworking Federation.
A long-serving member of the IDSystems team, for the past 20 years Edward has advised and supported do-it-yourselfers and renovators in identifying the most suitable glazing options for their projects. He recently completed a complete renovation and remodel of his home, transforming a tired 1960s home into a stylish modern family home. Their expertise ensures that each project is equipped with advanced, bespoke glazing designs that enhance both functionality and aesthetics.
Start by thinking about g-values
While I understand the importance of looking U-values When it came to thermal performance, what I didn’t realize was that, to get a ceiling lantern that performed the way I wanted, I needed to brush up on my G-values.
“Although U-value is the most shared performance indicator for windows, when you want to keep your home cool, you need to look for G-values instead,” explains Andrew Magge.
“The G-value tells you how much heat from the sun passes through the glass. The lower the number, the less solar heat enters the room. That’s what helps prevent ceiling lights from turning into a hotter space.
“That said, the answer isn’t just to make the glass darker,” Andrew points out. “People choose ceiling lanterns because they want natural light, so the skill reduces unwanted heat while maintaining a bright, airy feel.”
Vacuum glazing is a wise choice
There are many Glazing innovations In recent years it can be difficult to keep up with what to use in each type of application.
According to Andrew Mage, choosing a rooflight unit with vacuum glazing is a great idea. “Vacuum glazing can be a very good option for ceiling lanterns because it provides strong insulation in a very thin unit. Instead of filling the gaps between panes with gas, as in many double or Triple Glazed units, vacuum glazing removes air from tiny cavities between panes of glass,” he explains.
“The microscopic support pillars keep the panes apart, while the vacuum helps slow heat transfer. It works on the same principle as a vacuum flask. It’s important for ceiling lanterns because gas-filled units behave differently when installed on a slope or horizontally,” continues Andrew.
“The hot gas rises and the cold gas falls, which creates movement inside the cavity. In angular glazing, that movement can reduce the insulating benefit of the gas. In vacuum glazing that’s not a problem because there’s no gas moving inside the cavity. There’s nothing to rise, fall or circulate.”
“That means it can provide consistent performance whether the glass is installed vertically, horizontally or at an angle. For example, our glazing has a mid-pane U-value of 0.34 W/m²K – the lowest we know of any glass. The lower it is, the better it is at keeping heat in, meaning your room won’t be comfortable even in the colder seasons.”
Solar control glass can make a huge difference
Both experts I spoke to agreed Solar control glassWhen used in ceiling lanterns, it can make a huge difference and here’s why.
“Choosing glazing with a solar control coating is absolutely essential as it reduces solar gain from direct sunlight,” explains Edward Stobart. “The microscopic coating works by reflecting and absorbing infrared heat while still allowing light to pass through.”
“For large, south-facing or open ceiling lanterns, I’ll usually look at solar control glass,” agrees Andrew Magge. “This uses a more targeted Low-E coating to reduce solar heat gain while retaining useful daylight. With our solar control options, the G-value can be reduced to around 0.17 to 0.33, depending on the glazing set-up.
“That means much less heat gets in from above during hot periods,” he explains. “It can also block up to 99% of UV rays, helping to keep flooring, furniture, artwork and textiles from fading. It’s especially useful in rooms with direct sunlight.”
Adjust your roof lantern according to the room in which it is being fitted
with all Types of windowsThe room in which your ceiling lantern is being fitted needs to lead to specification – in short, what works for one space may be wrong for another.
“The best specification depends on the room,” says Andrew Madge. “A small, north-facing ceiling lantern can benefit from maximum light and insulation. A south-facing kitchen or Open plan kitchen The space will generally require strong solar control.”
“The amount of light transmittance can be customized to meet the specific needs of your home,” adds Edward Stobart. “Ceiling lanterns installed in large sizes or on south-facing elevations without tree shade may be better suited to glass with low transmittance, while areas with less sun-exposure will benefit from glass that lets in the maximum amount of light.”
Fit lanterns on the ceiling with built-in ventilation
While opening the windows is not always the best way Keep the house cool in summerThere are cases where it may be a good idea to have the ability to open your roof lantern for a cool breeze.
“When it comes Prevents overheatingIt’s important to consider whether a ceiling lantern with an opening vent might be a good idea, says Edward Stobart. Natural ventilation.
“The opening vents are usually electronically controlled and can be programmed to open automatically when the room below gets too hot – with a built-in rain sensor that closes again if the weather changes,” he explains.
Andrew Magge is keen to point out that shading – both inside and outside – can also help. “Exterior shading can reduce heat before it reaches the glass. Blinds can help with glare and comfort, but should not be used to protect against the wrong choice of glass. If the blinds need to be closed all summer, the roof lantern is not doing its job properly.”
FAQs
Should ceiling lights have low-e glass?
When shopping around for ceiling lanterns or Ceiling lights You may also hear the term ‘low-e’ glass – something that can benefit you in the fight against overheating.
“Low-e stands for low-emissivity,” explains Andrew Magge. “It’s a microscopic metallic coating built directly into the glass, designed to control heat movement without making the glass heavy or dark.
“Our standard Low-E coating offers 76% visible light transmittance,” continues Andrew. “In plain English, it still lets a lot of daylight through, so you keep the main benefit of a ceiling lantern. It also has a G-value of 0.58, which can work well for small, north-facing or shaded ceiling lanterns where overheating is less likely.”
There are many different types Roof glazing And incorporating it into your home design is a great way to pull in natural light where standard windows won’t work. Even small areas of ceiling glazing can have a transformative effect on previously dark spaces. Or, if you’re considering a more expansive glass, take a look at this Glass ceiling extension ideas For more inspiration.
