Solar Glass in Your Home

We never fail to be caught out by a heatwave in the UK, wouldn’t it be great if we could magically avoid most of the annual surprise… Please read on for solar-reflective glass options to reduce the incoming solar heat coming into your home.

All You Need to Know to Understand What You’re Getting

Solar glass blocks out both light and heat, so each option is usually described by those two separate values. For example, a solar reduction product labelled as “70/40” is designed to let through 70% of light and 40% of heat.

And I’m sure you can imagine there’s plenty of variation and far too much choice based on being able to choose your exact percentages…

In projects we work on, we always start by considering three simplified options:

• 70/40 is a standard go-to for most domestic homes. It’s an excellent blend, doesn’t look too different from normal glass
• 60/35 is a noticeable step up. If you have larger glass panes (perhaps a bifolding or a sliding door) that you know will be regularly hit by sunlight and you’re particularly worried about that extra heat, this is a worthwhile upgrade. Please do bear in mind that stronger levels of solar control will come with a stronger tinted appearance
• 50/30 is another large step up. This choice is on the borderline of domestic/commercial and therefore is on the borderline of what we’d be recommending for customers’ homes

More information about glass data

Reasons to be Careful

As wonderful as solar glass can be in the summer, the winter can be a very different story. Double glazed windows naturally help to heat your home in the winter thanks to their solar gain factor. Over-specifying your solar reduction will result in you requiring your heating more than you might expect for a lot of the year in the UK.

Going too hard on the solar reduction specification also puts you in a commercial bracket. Firstly, the frustrating item you’ll discover is the cost associated with something “commercial”. Secondly, you may be unhappy to discover a very strange level of tinted glass… Strong solar reflective options are ultimately aimed towards massive glass-faced skyscrapers and similar buildings where solar gain is simply huge.

Mostly though, an annoyance of these heavy solar blocking situations is that the glass works like a one way mirror. Sounds great for privacy right? Well…no… It’ll work as you’re thinking when it’s brighter outside than inside: you’ll be able to see out, no one will be able to see in. However, at night or even on a slightly dull day (obviously quite common in the UK…), you’ll likely have some lights on, and that means you’ve reversed the direction of privacy. You won’t be able to see out, and you’ll be lit up like a Christmas tree for everyone outside to observe.

More about glass options for our windows

Replace Just the Glass, or the Whole Window?

Via us, we only offer whole windows; our solar glass is fitted and sealed in the factory. So we don’t offer replacements. Ultimately by doing this, we know we’re offering a fully guaranteed system where every part is designed to work together – it’s why we also don’t mess around with mixing-and-matching new casements to old frames.

Of course, any sort of glass replacement requires a thought along the lines of: “is my window frame doing just as much harm as the glass?”. It’s not just about how the frame looks generally – old frames often will have bent out of shape, seals will have shrunk and hinge will be out of line. All these can create a situation where “closing” a window doesn’t actually mean it’s closed any more… The best glass unit in the world can’t solve that!

Combining the solar reducing glass with a brand new Class 4 airtight frame is obviously a fantastic upgrade. However, we realise not every budget stretches that far, and that level of upgrade is not always necessary.

Using our rough guidance on our main three options, you should be able to chat to any local glass replacement service and (hopefully!) organise a glass upgrade all by itself.

What to expect when replacing windows
Airtightness, keeping the heat in or out is about more than just the glass

I haven’t the time for any of this!

There’s also the DIY option our estimator recently used: sticking on a solar reflective film is fairly cheap, mildly effective and, depending on the skill level of the person sticking it on, can look somewhat neat.

While very inexpensive, this solution does come with a few downsides. First, it’s near impossible to tell what you’re actually be getting. Our lovely test numbers above have no bearing here; you’ll have to read reviews and hope. These films also tend to block a lot more light than you’d expect, so this bedroom got noticeably darker inside to the point where additional lighting is now on the cards. Finally, the installation quality is going to heavily depend on your DIY skills and patience: we strongly recommend looking at a Youtube tutorial or two, rather than the method taken here of “I’m sure it’s simple enough”.

We can add a tiny bit of data to this: for the specific example shown in the image below, we can check using a photography flash meter and some maths that overall the glass and reflective film blocks around 65% of visible light. Admittedly, our error bars on this measurement are comical, but the numbers do however give you an idea of how much darker your home will be. So, when going this route, it might be best to take the film off your windows when we go back towards winter.

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