Light, like air, accompanies us in our lives. With the help of the natural law of objects reflecting light, we have an understanding of the existence of objects. Lighting designers rationally allocate the amount of light used on the illuminated objects, so that it constitutes the light environment of buildings and spaces. At the same time, the light will give you strong psychological hints according to its “ideas”. The ancient Egyptians discovered that under the very clear and bright direct sunlight in the Egyptian area, shallow concave-convex relief gives people a mighty and powerful feeling. (1.0.1). However, the ancient Greeks found that under the less intense light in the Greek area, the reliefs looked extremely realistic (1.0.2). In the cloudy and diffused light of the Nordic region, the designers of Gothic cathedrals had to make the statues tall and mighty (1.0.3). This is all due to the different performance of sunlight in different geographical locations, and these principles also exist in the design of artificial light.
Everyone has a different understanding of light, but the impact of light on human beings has certain rules to follow. For example, in daily life, people generally follow the practice of working at sunrise and resting at sunset. Perhaps human beings have phototaxis, which is a habit of living things to approach or move away from light and is also a kind of biological stress, which is the result of long-term natural selection. What kind of light environment makes humans feel most suitable? It’s hard to express it accurately in words, but it can definitely be felt.
For example, when staying in some high-end hotels, the light atmosphere of the hotel makes people feel relaxed and comfortable, and there are many modes to choose from to adapt to various situations. Maybe you don’t understand lighting, but you must have enjoyed the comfort brought to you by lighting.
Artificial lighting is a process of infinite pursuit of natural light. On the one hand, artificial lighting is more controllable than natural light, and on the other hand, the quality of natural light is better than artificial light. In order to better combine the two, the profession of the lighting design was born, and those who practice at the same time are called lighting designers. They are familiar with natural light on the one hand and understand and be able to control artificial light on the other.
1. Natural light Vs Artificial light
1.1 What is natural light?
The natural light mentioned by lighting designers refers to the most common light produced in nature and used by living things for survival. Specifically include sunlight, that is, direct sunlight; skylight, that is, the light from the sun’s rays scattered by the atmosphere, that is, the light from the blue sky that we often see; moonlight, that is, the light from the sun’s rays reflected by the moon. These three kinds of natural light will show different color temperatures at different times (1.1.1).
Since the evolution of human beings is carried out in the environment of natural light, the architectural design and lighting design of modern society still take the most ingenious use of natural light as the highest state. Although firelight can also appear in nature, due to too much chance, and most firelight is artificially generated, it is generally classified as artificial light.
1.2 What is artificial light
In the field of design, artificial light generally refers to the light developed by people in the process of production and life, such as fire light, candlelight, incandescent light, fluorescent firelight, etc.
The use of artificial light is nothing more than a “supplement” to natural light. Just as early humans lived in caves where natural light could not enter, they needed supplementary firelight, and now the natural light at night is insufficient, so they need to be supplemented by lights. When natural light cannot meet the needs of people’s life and production, artificial light is needed. The artificial light used for supplementation is naturally aimed at simulating natural light, the closer the better. Various parameters about light, such as luminous flux, illuminance, wavelength, color temperature, color rendering index, color tolerance value, spectrum, etc., are developed step by step to consider the difference between artificial light and natural light.
From generation to development of artificial light, step by step to today’s LED (Light Emitting Diode, light emitting diode, is a solid-state semiconductor device that can convert electrical energy into visible light, it can directly convert electricity into light) era. Of course, there is also a level of imitation between old and new light sources (1.1.2).
1.3 Natural light and us
The vividness of natural light, its intensity as it changes direction, and its rich spectral composition are all important factors in determining our comfort. Comfortable light can reduce people’s fatigue and improve creativity. The change of light can not only stimulate our brains but also enhance the visual judgment of the environment. Such as the change from early morning to evening, from sunny summer to foggy winter. The natural light entering the room establishes the connection between people and the external environment, which is an important psychological factor for judging the space environment.
Few would deny the importance of sunlight or its beneficial effects on human health and well-being. Especially recently, more attention has been shifted to natural light. Although there are still many unknowns on how to achieve natural light-like lighting effects, there are also established conclusions: daylight with fixed changes determines people’s perception of human beings. The understanding of time (the seasons and the cycle of day and night or the rhythm of the circadian cycle) plays an important role in balancing the endocrine system. At the same time, sunlight also affects the evolutionary history of visual organs. The eyes work very efficiently during the day, and judgments about a particular lighting environment are always based, consciously or not, on a comparison with experience in daylight.
1.4 Can artificial light replace natural light?
The first thing to confirm is that no matter how advanced artificial light is, it cannot replace natural light. The evolution of human beings is carried out under natural light. Our genes have been used for natural light. Sunlight contains various elements that our body needs, which is also an indispensable part of our life. If we can only live in a space without sunlight in life, there are light sources that are infinitely close to sunlight in space. Whether we can grow healthily, the answer is no. Natural light is divided into two parts: one part is visible to our naked eyes, and the other part is the element we cannot see but our body needs.