Essence and effect of daylight
Daylight has been used for centuries as the primary source of light in interiors. As long as buildings have existed, the daylight has been an implicit part of the architecture and buildings.
Daylighting creates a visually stimulating and productive environment for occupants in all buildings, without undesirable side effects, such as glare, excess of contrast or reflection through carefully controlling shading devices and variability of daylight availability in spaces.
Daylighting system combines architecture, technologies and building systems. The integrated design approach is the best way for successful implementation of daylighting, involving decisions about the building form, building site, climate and zones, building components, lighting design and lighting control.
The use of natural light in buildings improves energy efficiency by minimising lighting, heating and cooling loads, reduce the building's electricity consumption and significantly improve the quality of light in the indoor environment.
Daylight in buildings
Natural light is a powerful architectural tool. The goal of daylighting is to collect enough daylight in the summer to turn off electric lights and collect as much as possible in the winter to help heat the building. The passive strategies like daylighting have become critical in reducing the impact of the built environment in sustainable buildings.
Harnessing daylight is done through building design, smart technologies and innovative materials. The passive daylighting strategies can collect and reflect light throughout the building. The orientation of a building can bring the best daylight throughout the building and harvest the solar gains through a variety of windows, atrium, skylights, solar tubes and other transparent openings.
To reduce heat loads, architects can also design smart external/internal shading devices to optimise. Advanced daylighting systems are designed to actively track the sun or passively control the direction of sunlight and skylight.
All you need is light.
Let there be a daylight — Both outside and inside buildings
Daylight is life. It allows people to interpret the surrounding world as light reveals details, colours, movements, and brightness. There is more to light than just daylight, there is also sunlight, the essence of the human ecosystem. Overall well-being is strongly connected to daylight because it affects the circadian rhythm and impacts productivity, physical performance and sleep. Find out more about how daylight plays important part in our lives and in our buildings.
Daylight in history
'Right to light', an ancient Roman law which dictates that once a man has enjoyed light through a window for a minimum of 20 years that a man then have a right to continue to enjoy that light, thus preventing others from building in ways that obstruct light.
The Egyptians, ancient Greeks and Romans, each of them worshipped their own sun god.
Basic hygiene requirements for housing — a summary of the state-of-the-art in the 19th century — also includes requirements for 'adequate ventilation' and 'as much access as possible to sunlight and full daylight (bactericidal effect)'.
'Daylight is part of the architecture, and there is no substitute for daylight', as design rule for architects and engineers.
Florence Nightingale, the founder of modern nursing in hospitals, in the 19th century, listed the daylight among the top 5 key elements that are necessary for the good indoor climate in buildings.
And the sunlight was used as a healer in practice, where for example, sanatoria were built to administer light therapy for people suffering from skin diseases and other ailments.
What is light?
In the eighteenth century, Dr. Samuel Johnson noted that 'we all know what light is; but it is not easy to tell what it is'. Today, the recognized explanation says that perceptible light is visually experienced electromagnetic radiation.
It is important to include the distinction 'visually experienced', as man in his natural environment is subject to radiation from the whole of the electromagnetic spectrum.
The part of the sun's radiation spectrum that reaches Earth comprises about 50% light radiation, about 45% IR radiation and about 5% UV radiation.
These figures also indicate the relative proportions of the energy contents of these different types of radiation.
Light, IR and UV radiations
We experience different types of solar radiation in different ways. IR radiation is absorbed by the skin, where cells or receptors register it as heat. When the heat sensation becomes too great, our brain transmits signals to regulate our body temperature by opening pores in the skin and creating a sweat, resulting in a reduction of the sensation.
As far as we know, human beings do not have any receptors with which we can experience UV radiation. On the other hand, the effect of an excessive dose of UV radiation can be detected — our skin turns red and we might experience a burning sensation and nausea. Light radiation is absorbed less by the skin than both IR and UV radiation.
All our light-sensitive cells or receptors are situated in our eyes and these react in different ways, depending on whether they have a biological or visual function.