When the history of the 20th century is re-written some 100 or 200 years hence – assuming there are still historians left to write it – environmental pollution
will doubtless figure highly in any assessment of the
century’s major ills – and in that category light as a
polluting factor will, I am certain, receive a much higher
billing than it does today.
Future commentators will be staggered by the huge
amounts of energy we have sprayed needlessly into
the sky – and the way we allowed all that obtrusive,
unwanted light to deprive most of the world’s people
of a visual connection to the heavens... and ultimately
to the visual splendour of the universe that surround us.
First of all, let’s define our terms. ‘Obtrusive light’ is
an umbrella term for all types of unwanted light. Then
there’s light nuisance: ‘artificial light emitted from
premises so as to be prejudicial to health or a nuisance’,
which is principally related to the adverse personal
effects of bad lighting to people in their homes.
Light pollution is actually defined by the UK government
as ‘any form of artificial light which shines outside the
area it is intended to illuminate, including light that is
directed above the horizontal into the night sky creating
sky glow (which blocks out the night-time stars) or
which creates a danger by glare.’ Spill light is a more
informal term that refers to light that obtrudes beyond
the area it was intended to light into surrounding areas
or on to surrounding properties. The much-used light
trespass is a meaningless term that has no technical of
legal definition and is untested in law.
So what can early 21st century lighting practitioners do
to try to limit this wasteful affliction? In what follows, I
have tried to boil down the most important measures
that could be taken – but although some of these are
relatively easy to apply in everyday practice, others will
depend on genuine political will, serious changes to
legislation and substantial investment in better lighting
equipment, with improved optical control.
We will also need to see profound cultural changes too.
It is a truism to say that electric lighting is a symptom of
modernity – and a symbol of affluence and civilisation.
Most people really do believe that ‘the more light
the better’. Darkness has only a negative value in our
cultures – it has come to signify danger, the ‘unknown’, a
state of primitive underdevelopment. People see lighting
as bestowing after-dark freedom to pursue leisure and
commerce; they also believe that lighting can offer a
degree of security and safety from crime and accidents
– and, of course, they are right. At the same time, the
availability of more effective, less expensive means of
creating artificial light is constantly increasing.
In the longer term, aided and abetted by the global
energy crisis and the need to reduce carbon dioxide
emissions, these assumptions will have to be challenged.
But this cultural battle, in which those of us with
a profound respect for both light and dark should
participate, is (sadly) beyond the scope of this article.
The following measures have been drawn from my own
personal observations of UK legislation, as well as some
of the best practice and policies in a range of countries
and cities, including Slovenia, Lombardy (Italy), the
Czech Republic, Tucson (Arizona) Chile, Spain and also
the ‘Dark Parks’ campaign.
First of all, we must improve planning requirements: all
new projects over a certain size should be required to
submit photometrically accurate renderings of the night-
time appearance of the building or structure, including
any overspill; with area lighting schemes (such as sports
facilities and car parks) there should be a requirement
for vertical illuminance calculations relating to nearby
properties, in addition to the horizontal lighting plots
for the surface being lit.
Planning conditions should also require the adoption
of a detailed post-installation maintenance programme
with night-time checks at specified intervals.
All towns and cities above an agreed size should
draw up an urban lighting plan, laying out design
standards and illuminance/luminance limits – this
lighting plan should be embodied in statutory local
These plans should set out quantified limits on façade
and monument lighting in luminance (not W/m2 as
in US legislation) for specific environmental zones. It
almost goes without saying that all lighting equipment
for new schemes should be equipped with anti-glare/
anti-spill devices as standard.
Lighting for vertical surfaces, such as advertising
signage, should be done from above, to direct light
downwards, wherever possible. If there is no alternative
to uplighting, as with much decorative lighting of
‘Darkness has only a negative
value in our cultures – it has
come to signify danger, the
‘unknown’, a state of primitive