Daylighting solutions are used to describe the controlled use of natural light in and around buildings. In practice, it is the simple execution of placing windows, reflective surfaces or any transparent facade element such that natural light provides illumination indoors during the day. However, it is a bit more complex  than that as it requires design considerations on all stages of the building design process from site planning to architectural, interior and lighting design.

Want to learn more about daylighting solutions in buildings? Read on.

What are daylighting strategies?

What does the term daylighting mean? And what is daylighting in architecture? Daylighting a building is composed of different elements such as direct sunlight, reflected light from the ground or the surrounding or even a skylight. This means that the design needs to consider orientation; building, facade and roof characteristics; size and placement of window openings, glazing and shading systems and the geometry and reflectance of interior surfaces among other things.

Alpin Energy Consultant Farah Ghanem, says “Daylighting analysis for sustainable assets is about finding the balance between visual comfort and energy efficiency” The overall objective of daylighting is to minimize the amount of artificial light and reduce electricity costs, in addition to improving visual comfort and indoor atmosphere.

The amount of daylight available, the occupancy pattern, and the control strategy can all affect energy savings. In addition to allowing natural light to enter the building, the installation of LED lights and a daylight responsive control system can help you save upto 75% of energy. This is because the best daylight is available during peak utility demand hours. These are important parameters of an energy efficient design. Electric lights are known to generate heat so turning them off or dimming them at peak hours can save significantly in cooling.

Our modern lifestyle ensures that we spend the majority of daytime indoors and so modern construction should make accommodations such that we receive natural light on a daily basis.

Designing a well-lit environment requires an understanding of many aspects related to the visual system as well as the non-visual system. Light is such an integral part of the human experience that the lack of such can send us into a spiral.

So, what are the benefits of daylighting? Let’s find out some the the advantages of receiving quality daylight:

Visual needs

Daylighting solutions have plenty of visual benefits, including for performance, productivity, and health and comfort. Here are the top reasons why daylighting solutions are so important.

Performance and productivity

How do you bring natural light into a building? Creating lighting conditions is more nuanced than one might expect. Different rooms are lit to satisfy different types of needs. You may notice that your office building is lit up much more significantly than your own house, which is much dimmer and cozier. This is by design and is done because we spend our days in the office and need to be productive and therefore are surrounded by bright lights while at home, we are unwinding from the day and need a much softer light to get us ready for the night.

According to a Edwards and Torcellini report of 2002, it was noted that there was a 15%  increase in productivity of employees after they moved to a new building that had better daylight conditions, which resulted in considerable financial gains. Studies also show that daylit environments lead to more effective learning. It was found that students in classrooms with the most window area or daylighting produced 7% to 18% higher scores on the standardised tests than those with the least window area or daylight (Heschong, 2002).

Good lighting gives attention to both our central vision and our peripheral vision, lighting the object as well as the surrounding. In the design phases this is supported by appropriate placement and sizing of windows to achieve an intelligent balance between the intensity of light, its location, direction and purpose.

Visual comfort

The light in a room should never impede our ability to see. If the lighting of a space is unsuitable or inadequate, it influences our performance and affects our health and personal well-being. It can result in unnecessary eye strain and give rise to symptoms such as eye irritation, fatigue and headache. Lighting conditions that can cause these symptoms are poor brightness and contrast, high luminance differences and flickering.

A good daylighting design provides large amounts of glare-free light; a poor daylighting design will require electric lighting to be used frequently – or large amounts of light, together with glare. Good visibility requires some degree of uniformity of light, if not the eye is forced to adapt too quickly to a wide range of light levels. Too high or too low contrast can also result in tiredness, headaches and discomfort. Generally, the human eye can accept greater luminance variations when spaces are lit by daylight than when they are artificially lit.

There are three main types of glare:

• Disability glare – This occurs when glare sources of high luminance (e.g. sun or specular reflection of the sun) are in the field of view.
• Discomfort glare – This is defined as an irritating or distracting, but not necessarily impairing, effect. Discomfort glare indoors is influenced by the full visual environment, including windows, reflections (especially specular), external surroundings and/or interior surfaces. Discomfort glare may cause headaches or fatigue.
• Reflections or veiling glare – Reflections on display screens or other task materials like paper, reduce the contrast between background and foreground for the visual task and thus reduce readability. This can happen when your computer screen is in the reflected view of a window causing you to strain to see.

The solution to reducing glare is employing shading devices, such as blinds, awnings etc. A flexible device can be individually adjusted depending on need and time of day. Windows located in more than one orientation, or on the roof, could adequately maintain daylight illumination for the visual tasks and provide a view to the outside, rather than being shaded to control potential glare sources.

Daylight availability

The primary target in the daylighting of buildings is to provide adequate lighting in the room such that daylight is the main, or only, source of light during daytime. There are several metrics in play to ensure this like the seasons of the year, the time of day, and the weather and require the assessment of  relative values.

While this does not affect the Middle East, it is still worth noting that Seasonal Affective Disorder is a depression-related illness linked to the availability and change of outdoor light in the winter. Studies suggest that 4 – 6% of the world’s population suffer from SAD while another 10 – 20% suffer from mild SAD, primarily in Northern America and Northern Europe. Light therapy is the most common form of treatment for this illness, requiring an individual to spend at least 30 minutes exposed to a special light box. As seasonal mood changes are relatively common, the amount of daylight in our homes or workplaces can be of considerable significance.

View

Meeting the need for contact with the outside living environment is an important psychological aspect linked to daylighting. Windows provide contact with the outside environment and allow for a protected experience in case of windy or rainy days.  A view of the sky, city or landscape gives a break from the tiring monotony and helps relieve the feeling of being closed in. The size and position of window systems need to be considered carefully in relation to the eye level of the building occupants.

Non-visual effects of light

Daylight has a wide range of influences on humans that go far beyond our need for vision. This is what we refer to as the non-visual effects of light. When we speak about health, balance and physiological regulation, we are referring to the functions of the body’s major health keepers: the nervous system and the endocrine system. These major control centres of the body are directly stimulated and regulated by light.

Much of human physiology and behaviour are dominated by 24-hour rhythms that regulate our health and well-being. They control out sleep/wake cycles, alertness and performance patterns, core body temperature rhythms, as well as the production of the hormones melatonin and cortisol. These daily patterns are called circadian rhythms and their regulation depends on the environment we live in. The variation of light, both daily and seasonally, is an important factor in setting and maintaining our 24-hour daily rhythms. Sleep disruption has been linked to poor cognitive function, stress, depression, poor social interaction, metabolic and cardiovascular disease and many other illnesses. An appropriate light signal during the day and darkness at night are therefore critical in maintaining key aspects of our overall health.

Different levels of light intensity for different durations trigger different circadian rhythms in the body. To set our body clock, morning light is the most important signal to receive as this increases our levels of alertness, allowing increased performance at the beginning of the day. This is why it is more difficult to get out of bed to start your day on a winters morning because the sun isn’t out yet. On the other hand, reduced light levels in the evening promote sleep at night. Daylight is not just a stimulus for vision, but acts as a key element in the regulation of many areas of human health.

Design Guidelines

Alpin consultants use their expertise and experience with green building certifications to solve problems of modern construction, including daylighting solutions. There exist several independent authorities that publish guidance material and set the criteria for best practice in Daylighting. One such authority is the Chartered Institution of Building Services Engineers (CIBSE), UK. The CIBSE has published its Lighting Guides on Daylighting and window design which describes a new suite of metrics of daylighting performance in existing buildings and new designs, from concept to construction documents. It is noteworthy that Daylighting is a very easy point to achieve in the process of a green building certification with a proven high return on investment.

LEED and BREEAM are two well known international methods of assessing, rating, and certifying the sustainability of buildings, while Estidama is regional to the UAE.  They all make recommendations for daylight as part of their assessment schemes but the variation lies in the calculation methods and benchmarks. Each method places different levels of importance on a view to the outside, glare control, and illuminance levels.

At Alpin, we’re glad to have worked on several projects, residential, commercial and other cultural landmarks in the region, that feature many of these daylighting solutions.

Want to learn more about how Alpin can help your project with our daylighting services? Read more about what we do at Alpin to promote sustainability in the built environment.

References

• Edwards, L., Torcellini, P. (2002) A Literature Review of the Effects of Natural Light on Building Occupants, National Renewable Energy Laboratory, U.S. Department of Energy.
• Heschong, L. (2002) Daylighting and Human Performance, ASHRAE Journal,vol. 44, no. 6, pp. 65-67.