The natural solution

Charlie Sharman of Cantifix discusses how the recent months have reminded us how much we need sunlight, and how glass technology innovations can help architects design for maximised natural light

There are many lessons we can take from 2020 about how we live, but, for some of us, it’s also demonstrated that we may also need to rethink where we live.

Cooped up indoors for months on end and cut off from our friends and the world outside, the way our homes work for us, or didn’t, has often been at the forefront of our minds.

Whether upping sticks to the countryside, extending for a little more space, or making simple changes to renovate and spruce up what we have, most people found themselves doing something to improve the space they live in.

Having spent even more time indoors during the winter months, it’s the perfect time to consider a crucial, but often improperly understood, element of our indoor environment – natural light. To understand why it’s vital to have access to natural (as opposed to artificial) light, it’s important to understand a bit about our physiology.

Our circadian rhythms, those finely-tuned fluctuations in hormone levels, brain activity and a host of other bodily functions, roughly map onto a 24-hour period (hence ‘circadian’, from the Latin ‘circa’ meaning ‘approximately,’ and ‘dies’ – meaning ‘day’). Over millions of years of evolution, our circadian clocks have learnt to calibrate themselves using fluctuations in light colour and intensity. Simply put, your body responds to sunlight in order to fulfil your particular needs at the time.

We evolved in Africa, right by the equator, and our circadian rhythms are still more or less set by light conditions there. In the mornings (relatively low light, more reddish in hue than midday sun), our melatonin (sleep hormone) levels are lowest and our cortisol (the so-called ‘stress’ hormone) peaks, making us more alert.

In the afternoon, our co-ordination, muscle power and reaction times peak, just in time to miss the worst of the equatorial midday heat, but still get out and rustle up some dinner. By the evening, where light levels are low and its colour is more red than blue, our body temperature rises to combat the cold and our melatonin levels rise, preparing us for sleep.

Although humans now live in diverse environments with wildly diverging light conditions, the optimum light levels for peak conditioning are something similar to those found on the equator, where there are 12 hours of light and 12 hours of dark every single day of the year.

The further away you are from the equator, the more light levels fluctuate with the seasons. A reduction in natural light during winter has been linked to weight gain, increased incidence of heart attacks and strokes and seasonal affective disorder (or SAD), a temporary form of depression associated with lack of sunlight in the winter months.

While it’s firmly established that we need natural light in order to function properly, what’s often less understood is that the ‘type’ of light we receive is crucial to our proper biological functioning.

This is a relatively new area of research, as it was previously taken as a given that ‘light is light.’ Not so – there are certain wavelengths of light in sunlight that are harmful and others that we want to maximise in order to unlock the benefits of natural light.

By now, we’re all aware that ultraviolet (or UV) light is harmful to our skin, contributing to premature ageing, sunburn and even cellular damage and skin cancer. Blue light is critical in regulating hormone secretion.

As previously discussed, in full daylight, which has a blue tinge, melatonin (the sleep hormone) secretion is reduced, and cortisol (the hormone that makes us more alert and active) levels shoot up. In the evening, when sunlight has less blue and more red in it, the opposite is true, making us sleepy and lethargic, just in time for bed.

Glass solutions
As architects and designers of spaces, we need to ensure we’re creating buildings that cater to human beings’ need for the right quantity and type of light. Using glass elements to light up frequently-used spaces can make a huge difference in quality of life, and these days glass can be used to create all sorts of structures. Glass roofs, walls, floors and even staircases can be used as part of a clever light-creating scheme.

However, just as not all light is the same, not all glass is created equal. There are coatings and films that can be applied to glass that change the quantity and quality of light transmitted. Low-e coatings, primarily used to reduce solar gain, also cut out harmful UV rays. This makes them useful in spaces like conservatories, where you’d expect lots of sunlight, but wouldn’t necessarily want to get sunburnt.

Low-iron glass, where trace amounts of iron are removed from the glass, is often used for its cosmetic appeal, particularly in thick glass, where iron can produce a greenish tint.

However, it’s also more effective at transmitting light, allowing through some 5 or 6 per cent more than standard glass.

More importantly, the type of light that’s transmitted by this type of glass is the all-important blue light in the spectrum of 450 nm to 485 nm, which research shows increases health and wellbeing benefits.

There’s plenty to consider when thinking about natural light and design and, as with most things in life, the most important factor isn’t quantity, but quality.

Charlie Sharman is CEO of Cantifix