Final Report Lot 9: Public street lighting - Amper

clear that light point locations cannot be changed without great infrastructural changes
and related costs. Therefore in re-lighting projects (with more efficient luminaires
and/or more efficient lamps) the pole distance usually can not be changed. If the new
installation supplies a useful luminous flux that is higher than necessary, the maximum
energy savings will not be reached.
• Public lighting can be connected together with the residential electrical distribution grid
or have a separate grid. A separate grid is sometimes required for telemanagement
systems.
• Lamps are only sold in a defined and limited power series (e.g. 50-70-100-150 Watt).
This implies that in real circumstances an overpowering can occur to meet the minimum
required light levels. Fine tuning of the maximum lamp power set point by using lamp
power dimmable ballasts or installing line voltage regulators can adjust the light output
to the required levels.
• The HID lamp power is regulated by the integrated ballast in the luminaire. This means
that when replacing a lamp with a more efficient one, there is no energy saving but only
more light output from the lamp. The only solution for this is again fine tuning of the
maximum lamp power set point with dimmable ballasts or installing line voltage
regulators.
3.3.2 Lack of interest by authorities
Public street lighting has to provide good visibility to users of outdoor public traffic areas (the
consumers?) during the hours of darkness to support traffic safety, traffic flow and public
security. On the other hand, the public authorities are responsible for procurement and
management of public lighting installations. If the public lighting installations provide the
required visibility, investments in energy saving projects that do not give quick earnings are not
a priority.
Examples:
• There exist many compromising motivating factors that can prevail at the design stage
of public lighting installations: budget and planning for investments in new street
lighting (infrastructure), pay back period for new investments, risk for quality
complaints for new technology, general resistance to change, etc…
• A new trend called 'city beautification' can be identified. The main objective is to make
city centres more attractive and install decorative street lighting luminaires with designs
that fit with historical buildings or the city character. The most important parameter here
is the aesthetic one and might compromise eco-design of street luminaires. In many
cases design architects are dominating projects and it will be important that these people
are aware of environmental impact (see also limitation in 3.3.4) and advantages of new
eco-designed products.
3.3.3 Limitations imposed by local light colour preferences
It is possible that the local population, or the local authority purchasing the equipment, has
preference for a certain light colour blend (gold, cold white, yellow, ..) that fits most there
99