Charlie Sharman, CEO at architectural glass and structural glazing specialists Cantifix, discusses the benefits of natural light and how selecting a bespoke glass solution can positively impact our spaces.
Sunlight is one of the most abundant and important natural resources on Earth, laying the very foundations for life. Natural light dictates our biological rhythms, provides warmth and influenced where we could farm and begin to settle in pre-history, creating the conditions for civilisation as we know it.
The importance of the sun has long been informally recognised. Indeed, creation myths from Christianity to Islam have placed the sun and sunlight at their heart. Sun gods sit at the heads of the pantheons of early Sumerians and Egyptians through to later Roman and Greek gods.
Recent scientific evidence points to the key role of sunlight in shaping our biology, everything from mood to physical performance.
In the last 150 years, with the advent of artificial electric lighting and dingy Victorian slums, with half the household living in mole-like subterranean darkness, in the West, we’ve neglected sunlight as a key tenet of building design (note the term “in the West” – vernacular architecture takes the environmental context of a building into account out of necessity).
More recently, brutalism, with its focus on utility and dark material palette, represented a nadir in our appreciation of natural light. After all, how much of that light is getting through a window set six inches into a concrete façade?
We’ve known that daylight is a key driver of our biological functioning since the 1950s. However, only in the last decades of the 20th Century have architects and those tasked with designing our spaces really taken daylighting seriously.
Physical and, later, computer modelling increasingly allowed architects to take daylight and the way it changes throughout the day into account. Coupled with this more sophisticated understanding of how sunlight works (the Walkie Talkie building aside), the move to all-glass facades on commercial and public buildings and the increasing use of minimally-framed or frameless glass in the residential field has opened up previously unexplored vistas of light.
How much of this is down to increasing recognition of the benefits of natural light and how much is down to a generalised move towards minimalism could be debated. The underlying fact remains – glass is becoming increasingly popular as a construction material.
But how do we ensure our designs actually contain optimal levels of natural light? Well, to some extent, it depends on the client and the space you’re designing. Night owls will prefer bedrooms that stay dark in the mornings well into the summer, whereas early birds would tend to appreciate the sun’s rays streaming in and gently waking them at dawn.
Similarly, the intended use of the space will dictate acceptable light levels – just as you probably wouldn’t want to have a dismal, dingy conservatory, you’d be equally frustrated battling glare from the sun in a home cinema space.
These considerations should inform our approach to daylighting, so it’s important to know both the client and how they want to use their spaces in as much detail as possible before starting any plans.
Similarly, the geospatial context and surrounds of a building will inform daylighting measures. There’s no need to go into the specifics of orientation here, as it’s well-understood that light changes in direction and intensity throughout the day and that buildings should be designed to accommodate that.
But there are other factors at play – if you’re designing a house along the equator, you can be absolutely certain that you will have 12 hours of daylight and 12 hours of darkness every day for 365 days a year. The further away you are from the equator in terms of latitude, the more wildly daylight hours fluctuate, anywhere between zero hours of daylight and 24 hours towards the poles, depending on the season.
People who live in 24-hour sunlight for six months might be thankful for periods of darkness inside, even if “dingy” is often used as a pejorative in architectural parlance.
Once we’ve figured out what the optimal levels and timings are for natural light, we can start to design buildings that work to maintain these levels throughout the day.
Before moving on, we should discuss glass specifications in relation to natural light, as not all glass is created equal. A specific bandwidth of light emitted by the sun – around 450-485nm, blue light in plain English – affects our circadian rhythms (physiological rhythms based on a 24-hour cycle of light and darkness that control hormone secretion, blood pressure, digestion and more).
Most glass contains trace amounts of iron, giving it a green tinge and blocking out this crucial bandwidth of light, robbing us of the benefits of sunlight.
To that end, it’s best to use low-iron glass, allowing the full visible spectrum of light through, transmitting all the benefits of natural light and avoiding biological darkness, which takes hold when we don’t get about 20 minutes of sunlight first thing in the morning and affects performance all day.
The full spectrum of light isn’t visible to the human eye, nor is all light necessarily good. UVA (320 to 400 nm) and UVB (280 to 320 nm) light have been implicated in the acceleration of skin ageing and other more serious health problems, so it’s a good idea to filter this out in some way, usually through use of a special laminate.
A glass package like Solstice Glass, recently launched by us at Cantifix, combines these features and more for the ultimate wellbeing glass specification. In fact, researchers are testing the effects of low-iron glass on light transmission in relation to wellbeing as we speak. We have teamed up with researchers are Oxford and Umea universities to test their Photon Space (an all-glass enclosure specifically designed to harness the wellbeing benefits of natural light) in Norway, with results due next year.
A key feature in daylighting is clearly glazing, but what are the options and how best to utilise them? Windows are your first port of call when considering natural light and there are a plethora of options here.
Some will prefer a frameless design, with others drawn to the heavily-framed Crittal style. Then there are questions of ventilation. Will a fixed window do, or does it need to open, in which case, will they be sliding or casement systems? In some cases, you won’t even have to choose between fixed and opening glass – there are companies that will hang an opening window inside a glass wall.
It goes without saying that glazed doors will also be near the top of most peoples’ lists for daylighting solutions. The first thing that springs to mind are your typical chunky sliding doors onto the garden patio, but again, options for glass doors abound.
Bi-folding doors are tending to give way to more minimally-framed sliding options. Some do away with framework altogether, building it into the glass unit, then back-painting the edges of the glass to completely conceal the frame. From simple casement doors to more elaborate guillotine opening options, there’s a solution out there for any utility or budget.
Beyond the obvious ways of getting more natural light outlined above, there are a number of options for the more adventurous or those working with difficult spaces. For instance, how do you get light to the basement?
Well, you could use solar tube lighting, also known as sun tunnels or sun pipes. These gadgets transmit light from the roof, via a tube made of reflective material, into diffusers above the space that needs lighting – an elegant, cost-effective solution.
Interior design is also vital in diffusing light around a space, illuminating even the darkest corners of a room. The most important consideration here is colour scheme – a lighter palette will diffuse light more efficiently than a darker one, which will actually absorb light.
Steps must be taken to ensure windows and other sources of light aren’t obscured or that any obstruction, like curtains, can be moved completely away from them. Light can also be blocked by external features, such as buildings, foliage and so on, so these should be taken into account and moved or removed if possible, otherwise you’ll need to design around them.
Back to more obvious solutions, and glass floors and roofs are another option. These work more efficiently as part of a light-well, starting with a rooflight at the top of a building and cascading light throughout through a series of glass floors.
Once again, there are a huge range of options to suit any scenario you might come across – glass floors can be placed internally or externally (usually with a non-slip coating, to prevent them becoming death traps in the rain), while roofs can be fixed, sliding, hinged or even pop right out of the roofline.
The sun has been at the centre of our lives in one form or another for millennia. However, as we increasingly sequester ourselves indoors, with modern living and working mostly taking place in offices, factories, pubs and dining rooms, we’re losing our connection with this crucial aspect of our environment.
This has become particularly important in light of recent events across the world. It’s never been more important that our spaces harness the life-giving rays of our sun – maybe ancient civilisations had it right all along.
All images courtesy of Cantifix.