Elements of Design: Light
Good light and good lighting — the one natural and the other man-made — are as essential to the success of a room as they are to sight, and yet, curiously, they are often the least planned, the least thought-about, of all decorating ingredients. How often do people fail even to think about the light factor in their rooms, or about how they should control, filter, or enhance light, until long after the decoration is underway?
Many people tend to think of artificial light as the counterfeit of daylight, regarding the two as totally separate issues. In fact, an effective lighting system that will provide comfortable light at all times requires you to strike a balance between the two, the one discreetly boosting the other when necessary. To do this successfully, you must understand the limitations of daylight — as well as its qualities. Daylight has, of course, all the advantages of variety: variety in intensity, in the form of almost hourly changes as well as seasonal ones; and variety apparent in colour, from intense blue to overcast grey, from the clear light of early morning to the pale lavenderish dusk of evening.
During each of these phases the interior of a building will look subtly different. That is why small windows should be left as uncluttered as possible to make the best of what light there is; why large windows should have screens, shades, blinds or sheers that can filter any superabundance; and why it is useful to see a room in as many lights as possible before deciding on a colour scheme and furnishings.
However, you should remember that daylight does not actually have great qualities of penetration, although the low angle of the sun in winter gives deeper penetration at certain times of the day than in the summer. In most average rooms, about 1 per cent of the available daylight outside will reach the parts of the space furthest from the windows, as opposed to as much as 10 per cent near the windows. In rooms with windows at both ends, the level of light from outside will fall off towards the middle. For large periods of the year, demanding visual tasks like reading, writing, drawing, painting and sewing can be done in solely natural light only if you are close to a window, and many rooms in buildings with a narrow frontage surrounded by other buildings will have poor lighting at most times of the day, whatever the season. This means that a good many rooms will always need the boost of artificial lighting for some purposes, and that many dark central areas in deep buildings — kitchens, bathrooms, as well as halls and passageways — will need constant artificial light.
This can raise quite a problem. During the day the eye becomes so adapted to the high level of natural light that, in order to remain equally comfortable in darker inner areas, it requires an equally high level of electric light — ie. a higher level than is usual at night, when the eye will have adapted to the lower overall levels of artificial light. This means that ideally you should have either separate lighting systems in perpetually dark rooms — one for day, one for night — or some form of dimmer integrated into the existing system so that the level of lighting can be controlled.