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\subsection*{Introduction to the environmental study of streetlighting as
an energy-using product}
\addcontentsline{toc}{subsection}{Introduction to the environmental study of streetlighting as}


Energy, mostly just electricity (power) using products have various
environmental impacts. The most important one is usually due to the
power consumption during their life; other impacts are due to their
manufacturing and other manipulations with them until their material
recycling.


Streetlighting is very special in its impacts. This is due to the fact
that \textbf{the very purpose of outdoor lighting is to produce a pollutant:
light}. Luminaires emit this pollutant to their surroundings, and the
pollutant spreads quickly and far, up to two hundred kilometres from the
sources of pollution considering its concentration close to the ground.
Unlike other power-consuming products, lighting devices whose light can
penetrate outdoors are to be judged primarily from the perspective of
pollution (mainly of twilight and night environment) by light. This
pollution, not much recognised even two decades ago, is ubiquitous and
has transformed our civilisation and wildlife a lot already.


The EuP study of streetlighting at product and system level began
without realising this peculiar property, treating streetlighting just
like other power-consuming applications. Describing the current
practice throughout the Union, the range of possible power consumptions
for the same task (putting the required amount of light on the street),
and some options to slow down the existing steady rise of power
consumption for streetlighting (or even to reverse it). However, without
the basic attitude that even if we need outdoor lighting, we have to be
aware that we are polluting the environment by it, not much can be
improved. The prevailing current attitude is ``the more light the
better'', light is considered as a universal blessing. This is not an
atmosphere in which the necessary trend could be started: pronounced and
steady decline of power consumption for lighting. And stopping the
existing growth of light pollution (see
\href{http://amper.ped.muni.cz/light/lp_what_is.htm}{http://amper.ped.muni.cz/light/lp\_what\_is.htm}) and reversing it into
steady decline as well.


In those regions where light is considered as a pollutant, AND outdoor
lighting is regulated by law
(see \href{http://amper.ped.muni.cz/light/EuP/legislation2.htm}{http://amper.ped.muni.cz/light/EuP/legislation2.htm}),
``\textbf{the less light the better, provided it still suffices}''
attitude is beginning to spread, and an advance in technology and huge power
savings take place. The necessary lighting tasks (illuminating streets
to provide good visibility whenever needed at night) are done much more
cautiously, avoiding emissions into directions where they are not
needed, and any over-lighting of the target surfaces. We can't avoid
light pollution, because we need streetlighting in most streets, but we
can much reduce it.


The awareness that man-made light is a major pollutant of our night
environment and that pollution should be minimised is the main motor of
the changes of existing lighting systems. Power and money savings result
from those changes, but as a motor for changes they would not be enough.
Of course, some good examples can be found even in sites where light
pollution is no widespread term, but this is solely thanks to the
expertise and enthusiasm of individual (and rare) personalities. Most
other examples in regions where lighting is not considered as polluting
are very bad. Lighting does not serve its purpose well, due to glare,
and is perceived as obtrusive by a significant fraction of the
population (up to one half), and its running costs are much higher. Bad
quality of lighting is erroneously ``solved'' by adding still more
light.


An environmental-minded study of streetlighting should start from the
notion that light is a pollutant and as such it should be applied just
in the necessary amounts, directions and times. The present study has
been but partly adapted to this view, at a late stage and not as much
as would be needed, due to lack of time (e.g., the very metrics proper
to evaluation of luminaires have been summarised just in January, see
\href{http://amper.ped.muni.cz/light/EuP/lp_fixt_par.pdf}{http://amper.ped.muni.cz/light/EuP/lp\_fixt\_par.pdf},
 technology of
least polluting and most efficent luminaires has been described in 
\href{http://amper.ped.muni.cz/light/EuP/FS.pdf}{http://amper.ped.muni.cz/light/EuP/FS.pdf}). Implementing this
view from the very beginning could have produced a more useful
document. Of course, it would demand cooperation of experts at this
field, which are very rare outside Italy at best. Let's hope even the present
text will prove a good aid for future efforts to make streetlighting
far less polluting (in all senses) and far more comfortable for its
users.

\end{document}
