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Designing in light – part 2

While our business is focused on windows doors and conservatories, at Admiral we are interested in all aspects of home improvement. This includes the little details that go into making a house a home. In this feature, we look at interior lighting. This post follows on from Conservatories – designing-in light.

Colour temperature and colour rendering

In lighting design, reds are considered ‘warm’ and blues are ‘cool’. Colour temperature is defined on a Kelvin scale: a high colour temperature of, e.g. 8000K relates to cool blue, while a colour temperature of 1200K might emanate from a log fire. Lamps marketed as being ‘warm white’ will have a colour temperature of between 2700K and 3000K.

Of equal importance to colour temperature is colour rendering: the spectrum of available light. If a light source renders colour accurately, visual contrasts are more apparent, highlighting subtleties of detail. Halogen lighting gives the best colour rendering but higher quality LED and fluorescent fixtures can now be specified with high values on the colour-rendering index (CRI 85+). When all else is equal, a cool white lamp is likely to achieve better colour rendering than will its equivalent warm white lamp.

Choice of interior surfaces

Lighter colours on the ceiling and walls will reflect more light within a space. Dark colours absorb  light and should be used selectively. To control glare and to distribute light evenly, ceilings and walls should be finished with a matte-finish light-coloured paint.

Ambient lighting

This is the general lighting in a room, which might come from an overhead fixture, from table lights and from up-lighters. Ambient lighting allows us to identify objects and to orientate ourselves. Ambient light is diffuse, i.e. there is no noticeable beam. Most people prefer warm white lighting for this purpose.

Task lighting

Otherwise known as reading lamps! Task lighting requirements differ from ambient lighting requirements, in that a more directed light is required. The lighting temperature might also be cooler (less yellow), in order to achieve a more accurate rendering of colour and greater contrasts. This would be important if you were engaged in visual arts and crafts, for example. It is also the case that, as we age, our eyes take longer to adjust to altered light conditions. Levels of task lighting should be balanced with levels of ambient light, so that we don’t arise from our chair only to bash into the door.

When buying lamp fittings for task lighting, look for narrow beam angles: below 600. For accurate colour rendering, choose lamps with a colour temperature of 4000K or above and / or with a colour rendering ability of CRI 85 or above.

Accent lighting

Accent lighting is aesthetic in nature. Its role is to illuminate beautiful things, whether these are architectural features in your home or your favourite paintings. Well-designed accent lighting also gives a degree of ambient light. Cool whites with colour temperatures of 4000K and above are likely to be most successful in these applications.

Energy efficiency

When compared with incandescent sources, LED lighting saves massively on electricity bills and, being long-lasting, these fixtures also do away with the cost and hassle of regular replacements. A key marker of a lamp’s efficiency is its lumens per Watt. In 2018, common LED lamps often achieve 65 lumens per Watt or better, which compares with maybe 17 lumens per Watt from a halogen lamp.

LED lighting need no longer be associated with the anaemic blue-white light emanating from first-generation fitments. In recent years, upfront purchase costs have been reduced significantly, and light from the much more powerful new-generation LEDs is ‘tuned’ to optimise selective characteristics.

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