Understanding The Science Of Light TO CREATE BEAUTIFUL HOME LIGHTING
Light is science. The correct application to create an ambience of light is art. You really can't use light without fundamentally understanding both. To that end, I have outlined the five key fundamentals of light - on the science & maths side - because without first principles, light just doesn't make sense.
FUNdamental #1 - LIGHT BEHAVES IN SPECIFIC WAYS
Light is a physical medium. Sure, you can't see it until it hits something, but it has physical properties that are non-negotiable. Like gravity is non-negotiable.
You can't "stop" light. It bounces around continuously until it has expended all of its energy. The only thing that "stops" light, is a solid, impenetrable surface. This is vital when you're thinking about light in a room. You don't need light sources everywhere - you can use the room as one giant light fitting, and the sources can be positioned out of the way - providing the light can bounce all around and fill in the space.
FUNdamental #2 - LIGHT IS A SPECTRUM
Light is Rainbows. Rainbows are Light - diffracted. Don't believe me? Try on a pair of MINT glasses, and you will SEE the spectrum of colour that makes up “white” light. The spectrum is different from every light source, depending on how that electric light source is made. Some have complete rainbows whereas some are less complete. Why does that matter? Because when light hits a surface, it reflects some of the colours - that's how we see colour. SO - if a colour is missing from the light source - then it follows that you will not be able to see that colour, as it cannot be reflected from the surface.
Sunlight split by crystal creates perfect rainbows
Diffraction filters split the colour in a light globe
When you realise that a "surface" can be anything from a tabletop, artistic masterpiece or even a face - then you can start to understand the importance of colour in light. Without it - your beloved (or perhaps worse - you yourself!) might start looking green - or red - or grey under the lights in your home. Less than ideal. The solution is simple - buy lights with the most complete rainbow possible - which is listed as a "CRI" or Colour Rendering Index number on the packaging. Look for Ra90+.
FUNdamental #3 - WE SEE THE “COLOUR” OF LIGHT AS GOLDEN OR BLUE
There is more than one type of colour when it comes to light. The content of the light is the rainbow (electromagnetic spectrum), but the LOOK of the light comes from something else entirely. The "Look of Light" is all about WARM or COOL light –known as Colour Temperature. Interestingly, though most of us don't realise it, is that daylight is really, really BLUE. It becomes most obvious when you have daylight streaming through a window alongside WARM electric light - then you can see the difference. In our homes, WARM light is best - and that means 2700K to 3000K on the label, or WARM WHITE. The “why” of measuring light in this way, the how and the variations and discrepancies is a fascinating and detailed topic, which I won't bore you with here.
Watch out for mixing your colours – if you have warm white light throughout your lighting design, if your range-hood is 6000K cool white, the contrast with the rest of your home will make the stove look like a spaceship ready to take off! Watch out for rangehood and other appliance light colours!
FUNdamental #4 - We measure the output of light fittings to understand their impacT
For a room to look and feel bright - you need a certain amount of light in it. That "number" changes, based on the colours of the room, the types of surfaces and the intended use of the room. A bedroom, for example, doesn't usually need to be brightly lit - but a bathroom certainly does.
So - how do you figure out if you have enough light?
The number to look for when choosing lights is the "Lumen" output. This number tells you how much light is being made by that light fitting. So - for example, a wall light that makes 800 lumens, compared to a wall light that makes 2600 lumens is going to perform very differently in a room.
If you have a small room, then maybe one or two of the 800 lumen wall lights is enough - providing you only want ambient light levels, but if you want LOTS of light, or you have a large room with high ceilings, you'll need to use the 2600 lumen light to put enough into the space to create that perception of brightness.
FUNdamental #5 - ENERGY EFFICIENCY MATTERS!
POWER. The amount of electricity consumed by a light fitting is critical when we're looking at energy efficient homes and sustainable lifestyles. It also has a big impact on your bills each month.
There is a direct correlation between the amount of power consumed by a light fitting and the amount of lumens created. There is also a direct correlation between the cost of the light fitting and how efficient it actually is in reality! Cheap lights use more power.
LED is a far more efficient lighting source than any that have preceded it, and so, when used intelligently, can bring the perfect lighting into your home, for the lowest impact on the world and your hip pocket.
Critically - when comparing LED light fittings and light globes – make the comparison on the lumens first. You can have a whole range of lights creating the same lumens, for varying wattages. The amount of light they make is far more important than the amount of energy they use – although both are very important, if you can get the same lumens for less watts, that is definitely worth exploring.
Now that you have a handle on some of the more important first principles of light, you are in a much better position to make good decisions for the light in your home.
