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.
Projecting light onto neighbouring properties can be a nuisance and disturb
sleep patterns.
Projecting light into the sky obscures our view of the stars.
.. All of it wastes energy..
Why is this important?
Producing energy costs money and produces carbon emissions - it is an enormous
waste to project this energy into trees and into the night sky. It does no
good. It does only harm.
All of earth's life forms have evolved according to the natural cadence
of night and day, of darkness and of light. It is dark at night because that
is the way the world works. Should we floodlight the darkness and disturb
the wildlife that has evolved over billions of years according to the rhythms
of nature?
We know from the large increase in sales of blackout curtains that projecting
light onto our neighbour's windows can be a nuisance. Why should we have to
black out our bedrooms? Where should the responsibility be?
Last, but by no means least, shouldn't we have a right to see the stars
by night, just as we have a right to see the sun by day?
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
