Many of us live in villages or rural communities - we should be able to see the Milky Way in all its glory just by stepping outside on a clear night. But the natural wonderment of our night skies is often obscured by powerful and misdirected exterior lights. Please consider the following photos:
Can you see the burglar? (You may need to look carefully) This shows a typical "Security Light", installed (as they often are) such that the light shines horizontally
Now can you see the burglar? A properly aimed shielded light provides a much higher quality of illumination
What is the difference between these two photos? There is no difference, apart from the angle of the lamp. It is the same burglar, the same camera angle, and the same exposure. It is even the same lamp, except that in the first photo it was purposely misadjusted to emulate a typical "Security Light".
Does the "Security Light" offer any actual security? You may agree that it offers less security because the glare from the light is so intense that it obscures the burglar. The term "Security Light" is purely a marketing invention. In reality it is a basic unshielded exterior floodlight which can cause significant problems if not fitted carefully. Much better visibility of intruders is afforded by not using a "Security Light" and instead using a shielded light, as above. It also provides a much more pleasant illumination because we can see so much more without being blinded by glare.
A 500W 'Rottweiler' projects light into the trees and sky,
disturbing wildlife and obliterating the night sky
A properly aimed shielded light reveals the splendours of the
night sky whilst providing plenty of light where it is needed.
Orion image courtesy Jeremy Perez <www.perezmedia.net>
These days many exterior lights have half the power of the most powerful lighthouse in Great Britain. Is there justification in using this much power to illuminate a garden? To compound the problem these lights are often fitted such that they shine too much light upwards, rather than downwards, where the light is needed. Can we truly project this much light wherever we want with impunity? What about the effect on our neighbours, on wildlife, and on those who wish to view the night sky?
Please consider the top photo to the right.
This photo was illuminated by a 500W "Security Light" fitted (as many are) such that much of its light is projected into the trees and into the sky. The light trespass is enormous, projecting some 200 yards onto neighbouring properties, and obliterating the night sky.
According to the RSPB, CPRE, CfDS, National Geographic, and many others...
Why is this important?
Please consider the bottom photo to the right.
This photo was illuminated by a properly aimed shielded light - an "Anti Light Pollution" floodlight. This was a similar floodlight to the one used to illuminate the burglar in the photo above and as can be seen, it provides ample light in the foreground, where light is needed. But it has a sharp cut off (like a car's headlight when dipped) so that the unwanted light is considerably attenuated. The amount of light reaching the rear of the garden (where light is not needed) is minimal. The trees are essentially in darkness. This is how it should be. And the magic of the night sky begins to emerge. This is how it should be too.
Walk around any community after dark and you will readily see examples of upstairs windows being floodlit by "Security Lights" on adjacent properties.
It can often be quite easy to stop the negative effects of exterior lighting described above:
Please note how the angle and position of the lamp changes
in the above illustrations.
With some lights it is possible to stop light trespass by merely adjusting the lamp downwards, so that the light shines where it is needed.
Please see the illustrations to the right.
Unfortunately most "Security Lights" are unshielded and can scatter light onto neighbouring properties however they are positioned. If an opportunity arises to replace such lights please consider shielded lights, often called "Anti Light Pollution" flood lights. They are usually inexpensive, often under £20.00.
Shielded light is much more pleasant because it is free from blinding glare. The lack of glare helps to identify intruders. Since the light is focused, less energy is needed. Most "Security Lights" use a 300 Watt bulb but a 150 Watt bulb is usually more than adequate with a shielded light. This saves energy, saves cost, and helps us to see the stars.
The Anti Light Pollution Floodlight
This is a shielded form of external floodlight which reduces light pollution considerably by preventing light spill above the horizontal. It provides a much better quality of illumination, saves energy, and has all the additional benefits described above. This particular model is from Homebase - it is sold as Model #536270 "300W Anti Light Pollution Floodlight" - the price is only £14.99. Unfortunately they spoil things somewhat by including a 300W light bulb. This is excessive because all the energy is focused, thus a less powerful light is needed. The solution is to change the light bulb to 150W which saves energy and provides very good illumination. The 150W linear halogen tubes can be purchased in the 118mm width from many places including Amazon, My Green Lighting, and stores such as B&Q where they are available off the shelf. They should cost between £1.20 and £1.99. The more efficient types consume only 120W while providing 150W in equivalent illumination.
The Homebase Model 536270 is an excellent shielded light but it is very important to ensure the lamp is angled down as far as it will go, as in this photo.
I have three of these installed, all with 150W light tubes, and the quality of light is excellent. They are very reliable. Similar lights can be purchased from Amazon, B&Q, Tesco, Argos, etc. Please try an online search for "Anti Light Pollution Floodlight". You shouldn't have to pay more than £20 and many are cheaper. They are easy to fit but if you need help please let me know (contact details below).
Why Not Save Energy?
Many homes can save from 100 - 300 Kilowatt-hours of energy per year solely by improving exterior lighting. This may be one of the least appreciated areas of energy usage.
(This simplistic model assumes a home with three exterior lights (one at the front and two at the rear) wherein 300W light bulbs are changed to 150W, with an average duty cycle of one hour in 24 hours. That is a saving of 0.45 Kilowatt-hours per day, 164 Kilowatt-hours per year. A home with two external lights might save 109 Kilowatt-hours per year, and a home with four external lights (such as ours) might save 219 Kilowatt-hours per year.)
When the light is concentrated, less energy is needed: a 150W shielded light provides all of the illumination of a 300W unshielded model and the quality of illumination is much better: it avoids unpleasant glare, helps identify intruders, avoids light spill onto neighbouring properties, avoids light spill onto trees, and helps us see the stars.
Why Not Save Energy - and help us see the stars?
I will be pleased to help with further information:
With thanks to many, especially to Bob Mizon of CfDS for his tireless work