It’s no great surprise that people are attracted to natural light and that most of us feel better when the sun comes out. However, beyond the “feel good” factor there are many tangible benefits to increasing the amount of natural daylight entering a building.
Daylight is a vital natural resource that will significantly improve the environment within any building. Evidence from the numerous physical and psychological studies undertaken on the subject, suggests that buildings enjoying high levels of natural light are literally more successful than those more reliant on artificial light. In all environments our brains respond better to natural light, which means people perform better.
Much of the research on the benefits of natural daylight has focused on the learning environment. Enhanced student performance and motivation, increased teacher and student attendance, reduced energy costs, as well as a positive effect on the environment are some of the improvements seen in school buildings that use well-planned day lighting concepts.
One such study by Sacramento California, ‘Light Helps Pupils Learn’, is one of the largest ever undertaken on naturallight in schools. It suggests that children learn faster and perform better in exams in classrooms with more daylight. It identified that exam results were up to 26 percent higher for schoolchildren in classrooms with plentiful natural light than for those in classrooms with little or no daylight. These findings are reinforced by Alberta Education’s, ‘A Study into the Effects of Light on Children of Elementary School Age’, which showed that natural light also has a positive effect on the health of children, as well as on rates of attendance and achievement.
With such a compelling list of benefits, one might be surprised that optimising day lighting in schools is often regarded as a design preference instead of a basic responsibility.
Many of these benefits can also be applied to the workplace. Daylight improves concentration so that working environments, be they factories or offices with natural light, tend to achieve increased productivity.
Research into retail environments suggests that in many situations sales tend to be better in naturally lit locations; colours are more vivid making goods appear attractive and encouraging customers to spend more time in these areas. A number of the UK’s leading retail organisations include large areas of rooflights in specifications for all new build projects to ensure a high percentage of evenly distributed natural light within the interior.
Many scientific studies conducted in the healthcare sector also support the conclusion that natural daylight has proven health benefits. Daylight helps to shorten patient recovery times, improves their mood and generally promotes well-being. So it’s no surprise that architects involved with hospitals, housing for the elderly and other healthcare buildings are constantly adjusting and updating their designs to reflect the importance of introducing daylight and, more specifically, natural sunlight.
But it’s not just the elderly or unwell that can reap the health benefits of natural light. It is estimated that up to 20 per cent of the UK population suffer from Seasonal Affective Disorder (SAD), a form of winter depression. These individuals are known to respond to the hormone serotonin, whose production is triggered by natural daylight.
Natural light also offers an environmentally friendly means of saving money on energy costs. It stands to reason that the more natural light entering a building, the less energy for lights and heating is required.
Even in our rather dull climate, passive solar gain provides significant potential to reduce energy usage. Buildings that enjoy high levels of natural light evenly spread throughout will be heated naturally for a considerable percentage of the year.
It's estimated that 25 to 40 percent of a commercial or institutional building's energy is needed for lighting, often at peak-demand prices; day lighting may save up to about 50 percent of that, depending upon how natural light is used.
What does the law say?
Legislation issued in 2002 made it a legal requirement for buildings to have adequate natural daylight as part of the design. The legislation now states that a minimum 20 percent of the wall area or 10 percent of the roof area mustcomprise of light transmitting elements.
For schools, specific guidance on natural lighting is available in Building Bulletin 90 (BB90) ‘Lighting Design for Schools’. This provides essential guidance for both primary and secondary schools, whether for new or refurbishment projects. It stresses that natural lighting during daylight hours should always be the major source, supplemented by electric light when needed.
The role of the rooflight
Rooflights can help to provide natural light with qualities appropriate to the use of the building. Rooflights let in light from the brightest part of the sky and are not generally affected by external obstructions, such as trees or other buildings. They also provide a more even pattern of light than vertical windows.
Rooflights can form part of an effective technical lighting scheme, particularly in conjunction with efficiently controlled artificial lighting, to produce specified illumination levels for particular tasks. According to leading consultants, horizontal rooflights provide three times more light than vertical windows (the equivalent of 10,000 candles on a sunny day), which is more than 200 times the light needed for most educational or work related tasks.
In addition, rooflights can also add to the more subjective qualities of spaces as an integral part of the building’s architecture. They can provide views of the sky and promote a sense of well-being and connection with the outside without the distractions encountered with views through vertical glass windows.
These facts are well understood by most people involved in building design. However the huge potential of rooflights to provide exactly the amount, type and distribution of natural light required to meet any given specification is not always appreciated.