For a long time the measurement of light was not a top priority for the majority of us. The lighting intensity in a room was often decided on a hunch, for large room, use a hundred watt bulb, medium sized room, put in a sixty watt bulb and so on, as was the familiar and simple nature of standard incandescent bulbs. But since the introduction of a much wider range of lamps on the market it has become much harder to gauge what intensity you can expect from any particular lighting source. This is why it is important to understand more about the process of measuring light, to avoid getting too much or too little for the space you are trying to light.
The standard incandescent lamp that we are all familiar with and are used to buying for our lights is quickly falling out of favour due to its high energy consumption in these eco-friendly times, and whereas a sixty watt incandescent lamp will provide an average sized room with substantial light, as will a fifteen watt compact fluorescent lamp or forty watt halogen lamp and with each variation of lamp there is a different set of ecological and economical benefits and shortcomings.
Having a good understanding of light measurement is very beneficial, some would say, essential when designing a lighting plan, it can also ensure that you are not over paying for unnecessary power by choosing the wrong lamp type for your fitting. Perhaps the process of light measurement is most useful when you start to think about task lighting and additional emphasis lighting. Task lighting should be properly planned and monitored to ensure that you have enough light to fully concentrate on the actual task at hand and to clearly see exactly what you are doing. As for emphasis or accent lighting, it is important that it both does provide the room with the attractive mood setting light that you desire but also does not intrude too much on other light sources in your plan and become cluttered or give an uncoordinated feel to a space.
Lighting sources, lamps etc on the mass commercial market are most commonly measured in the photometric unit of Lux commonly marked with the lx symbol. The Lux measurement is a unit of illumination equal to one lumen per square metre (one Lux = a distance of one square metre of light given by a source). A Lumen is the unit of light from an artificial source such as a bulb rather than a candle. An example to gauge light intensity of a lumen would be; one hundred watt standard tungsten incandescent (new and clean) produces around twelve-hundred lumens. However much more than this has to be taken into consideration, such as where the light is positioned, all the surrounding objects and the effect they can have on light, whether they reflect of absorb light. Also the colour scheme in a room, as different colours absorbs more light than others. This is why it is always important to ask the advice of a professional designer or interior decorator when designing an intricate lighting plan.
For an accurate Lux reading you must use a light meter; however this is not always an option. But there is a way to get a strong estimate on the measurement of a light by firstly measuring the space which you have to work with then multiply the length by the width to get a measurement in square metres. Then add up the lumen ratings for all the bulbs (light sources) in the room, divide the total lumens by the square metre specifications to get a Lux reading for all or a single light source. For example; if you have an area sized one hundred square feet and a combined lumen output of three thousand, 3000/100 = 30 Lux per square foot.
Simply put, measuring light can be a rewarding process when understood and carried out correctly. Not just to ensure that the lighting in your room is just as you imagined it would be to provide you with some satisfaction, but also to fend off any health risks that can develop as a result of under or over illuminating a space. As we all know, light travels in straight lines. But beneath that there is vast and intricate scaffolding of equations, all constructed with the aim of setting the optimum mood, highlighting the material and knowing exactly what you are paying for.
