The Case For Daylight

Our clients frequently ask us to maximise natural light when undertaking work to existing properties.

While sunlight and daylight have a long history of being associated with health, it is widely recognised that there are both benefits and disadvantages. A good design should consider both. This article outlines the aspects to consider, giving tips for good daylight penetration.

Why should we maximise natural light?

Short days, dark winters and the abundance of poorly lit historical houses should be enough to prompt a craving for natural light. During the pandemic, with people spending more time in their homes, the desire for more light and nature has increased exponentially.

The health benefits of sunlight are widely known. Here are some:

- At the beginning of the twentieth century, it was scientifically demonstrated that ultraviolet wavelengths of light had medical benefits. Exposure to light radiation was also used to treat some diseases, such as tuberculosis. This knowledge found an architectural response in 1932 with the completion of Alvar Alto's Sanatorium.

- When exposed to sunlight, the skin absorbs vitamin D. This critical nutrient prevents bone loss and reduces the risk of heart disease, weight gain, and various cancers.

- We know that natural light improves circadian rhythms, sleep patterns and reduces the risk of depression. 

- Since mental health and sleep often go hand in hand, we now know that well-lit space impacts productivity.

- It represents an element of connection with nature: a space with a good dynamic and diffuse light condition evokes the passing of time and gives a sense of calm.

... but there is more than health:

- Natural light is a free source of energy that reduces bills and our impact on nature. However, the more energy-efficient light fittings have become, the more people started to use artificial lighting. Low-cost, energy-efficient fittings have made it too easy to replace natural with artificial light.

- Natural light (sunlight) still provides the best possible light, even though the quality of newer generation LED lights have significantly improved light output quality.

On the other side, there are some disadvantages. For example:

- We all know that to maximise the natural light penetration in a building, we need to increase the opening sizes or the glazing surfaces. This, however, may cause too much solar heat gain depending on the orientation. With global warming, the overheating of properties will be a more pressing issue in the future. Although the UK Building Regulation does not adequately regulate this aspect of building performance, it should not be overlooked.

- Increasing too much glazing can also cause too much heat loss as glass surfaces typically lose more heat than a solid building element.

- Another disadvantage could be that excessive light or direct sunlight could cause discomfort to the eye. Too much glare or direct sun with its dramatic contrast between light and shade can tire the eyes, particularly when reading, watching videos or doing other tasks.

- Moreover, too much ultraviolet light can cause discolouring and ageing of materials.

Now that we know all the pros and cons, what is the best way to design with natural light?

In the design process, it is crucial to find the right balance.

Every project is unique because of its location, circumstance and brief. The way we integrate natural light in a house project can change depending on the habits and needs of each client. Therefore, our first step at CMA is to understand the real reason behind a brief and our client's real needs and desires. 

At the outset of the design process, we assess the house orientation and the risk for solar heat gain or excessive direct sunlight. Suppose the context and the existing conditions do not allow the optimal glazing positioning. In that case, a few design moves can mitigate the disadvantages of a suboptimal situation:

- High Performing windows: Glass technology has evolved in the past 20 years, and glass can be used in ways unthinkable only a decade ago. As openings become bigger and single glass panes larger, the glazing systems have become more thermally efficient. The glazing systems' U-value (thermal transmittance) can reach very low levels. Although the UK Building Regulations do not require high performing glazing systems, triple glazing units will shortly become the norm, reducing the heat loss levels closer to the Passive House standards. Along with the glass, the framing system needs to be carefully selected.

- Prevent overheating: Since the glass is transparent to the light and near-infrared radiation, the windows also let in heat, giving rise to the well-known greenhouse effect. There are different ways to overcome this issue:

• Shading devices: External devices, such as horizontal or vertical louvres or awning canopies, are the most efficient ones.

• Smart window: Smart glazing allows direct sunlight to pass while blocking near-infrared radiation. This is achieved with an infrared shielding coating that locks more than 90 per cent of near-infrared radiation while transmitting more than 80 per cent of visible light.

- Internal layout and finishes: A holistic design approach should consider interior design, material selection, and fabric design. Light finishes and colours that reflect light are ideal for spaces with little natural light. Avoiding them in bright spaces is advisable as they could cause too much glare. 

The interior layout of rooms could be crucial if used for specific tasks, such as reading, working or preparing meals. Glare and direct sunlight should be avoided in these spaces, as too much contrast between lit and shaded areas could tire the eyes.  

- Sky component: Openings that give sky views let in more light than those without, as the sky is bright even when it is not sunny. When designing openings, the size and shape should be considered with outdoor obstructions.

5- Triple glazing vs Blue light. We now know that traditional glass stops part of the blue light spectrum of the natural light that affects the sleep patterns and the circadian cycles. If the triple glazed windows perform thermally better on one side, on the other hand, the blue light gets almost wholly filtered. Some companies provide low-iron panels that allow perfect clarity, increasing light transmission. It not only allows more light through with positive effect alertness and productivity.

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If you found this article helpful and have a relevant project, please get in touch. We will be happy to help.