Because commercial and institutional buildings operate primarily during daylight hours and with clearly-defined schedules and because specific tasks are conducted in given areas, these kinds of buildings often lend themselves to comprehensive, systemized day lighting plans. And in these buildings, day lighting makes sense because of both energy savings and worker satisfaction.
When a building is flooded with well-controlled natural light, the amount of electricity needed for lighting may plummet. It's estimated that 25% to 40% 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% of that, depending upon how natural light is used
Daylight is really just the act of illuminating rooms naturally. Any time you're able to light a room with a window or skylight instead of flipping on a light switch, you are day lighting. It's that simple.
Workers prefer brighter, more naturally-lit environments, too. In fact, a number of studies support the idea that natural light has positive psychological effects on people. They suggest both that our brain perceives the color properties of natural light as "normal" and that we respond in a positive, physical way to its intensity.
Day lighting taps into the five-billion-year-old fusion reactor called the sun. Using sunlight costs nothing to the environment but pays big dividends to building occupants. The result is a compelling, efficient lighting solution that also protects the environment. By consuming less energy, daylit buildings reduce fossil fuel use and carbon dioxide emissions associated with global warming and climate change.
Daylight is an essential natural asset. For those of us living in temperate Northern climates, the beneficial effect of sunlight is easy to recognize; a couple of sunny days seem to lift everyone’s spirits. Research also shows that suicide rates are considerably higher in parts of the world where daylight is very limited for significant parts of the year. On a slightly less dramatic but equally significant level, there is also a growing body of evidence to suggest that buildings enjoying high levels of natural light are literally more successful than those more reliant on artificial light. In all environments the eye and brain functions respond better to natural light, so people perform better, while passive solar gain can reduce energy costs.
Research demonstrates a clear correlation between classrooms with good natural light and improved student performance and even attendance. This is because in natural light children concentrate better so are more focused and less easily distracted. Some studies suggest that health is also enhanced helping to explain the improved attendance.
In the UK we are used to hearing of SAD, Seasonal Affective Disorder, a clinically diagnosed condition in which the lack of sunlight in winter makes people feel ill. Natural light helps people to feel better but it can also aid the healing process. In hospitals, studies have proven that the recovery rate of patients is accelerated where levels of natural light are increased.
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 and true, 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 roof lights in specifications for all new build projects to ensure a high percentage of evenly distributed natural light within the interior.
People like bright naturally lit environments, evidenced by the huge popularity of domestic conservatories and sunrooms. It is therefore logical that in their leisure time people prefer facilities enjoying high levels of daylight. Most sporting and recreational facilities today try to maximise natural daylight in recognition of this.
The revised Building Regulations Approved Document L, for the first time acknowledges the well proven benefits of natural light, and the effectiveness of roof lights in providing daylight into a structure. In industrial and commercial buildings revised Document L of the Building Regulations recommends a minimum roof light area of 10%, and a notional Standard based on 20% roof light area.
