Electrical Contracting News (ECN) October 2016 | Page 52
SPECIAL FEATURE
Lighting must be designed to assist occupants
in whatever task they are undertaking.
They only account for around half of light
sales at present but that figure is growing
quickly. While their energy efficiency is
competitive, they don’t always outperform
the most efficient conventional light sources
so careful analysis is needed. Again,
the context and setting of the lights in a
particular environment must be considered.
One distinct advantage of good quality
LED luminaires is their longevity, which
limits the time and expense associated
with regular lamp replacement. However,
LIGHTING
some of the less reputable manufacturers
of LED luminaires may have overstated the
lifespan of their products – a problem that
may not become apparent to customers
for some time yet.
Important considerations with regard
to the specification of LED technology
include luminaire design. The LED
must be allied with a suitable luminaire
that incorporates appropriate thermal
management, properly designed optics
and a high quality driver. These will help
maximise the lumen output of the LED.
The lifespan of an LED is also a vital
consideration. The ‘practical life’ is defined
as the period between the LED first being
activated and the point at which its output
falls below 70 per cent of its initial output.
This is traditionally symbolised by the
letter ‘L’ so, to give an example, a quoted
specification might be: ‘L70, 50,000
hours’. However, for greater clarity, a
further metric was added to the equation,
with the letter ‘B’ denoting the percentage
of the sample batch no longer producing
70 per cent or more of the initial output.
Therefore the lifespan might be quoted as
‘L70B10 50,000 hours’, which means 90
per cent of the batch is still performing at a
minimum of 70 per cent of the lumen value
after 50,000 hours.
By looking at the lumen performance of
the LED luminaire and not just its wattage,
the specifier will be able to compare the
true performance of the LED luminaire
against a conventional lamped luminaire.
This will identify the benefits in reduced
energy consumption for a real application
while retaining the correct illumination level
and quality.
daylight coming from windows or rooflights
for the purposes of consistent light quality
and cost effectiveness.
6. What is the application?
8. Who makes the decision?
It is vital to carefully consider the
application to determine whether an LED
is in fact the most appropriate solution
for a particular situation. Applications
where an LED does not offer the optimum
solution include situations where capital
cost is the key driver, the project is
intended to have short operating hours
or the temperature of the environment
is especially hot as can be the case in
certain industrial areas. In contrast, there
are situations where LED lighting is the
obvious solution. These could include cold
applications, environments where the cost
of maintenance and replacement of lamps
is difficult or expensive, or where the
operating hours are such that the energy
savings are warranted.
A good supplier will act as a partner in
the decision-making process, ensuring
that reliable information and guidance
is available throughout and that all
stakeholders, whether finance directors
or facilities managers, are engaged.
All of these groups will have a useful
perspective on how the end result should
be configured.
One of the key questions to address is
the likely return on investment. Any forecast
of energy and maintenance savings should
be balanced against the initial capital outlay,
which enables a defined period of payback
to be estimated, whether it is six months or
three years. A good supplier will provide
this detail upfront to ensure that nobody is
left in the dark.
7. Which technology?
In summary
Other recent technologies, including
control and automation systems, can play
a considerable role in energy efficiency.
For example, lighting can be automatically
deactivated in a particular area when it
is not occupied, which reduces reliance
on manually switching off lights. Another
increasingly common technique is daylight
balancing, whereby light levels are
automatically adjusted in line with natural
A properly planned lighting scheme can
reduce long term energy costs and even
raise productivity through its efficacy,
efficiency and suitability for the space in
question. For this reason it is worth taking
time to understand both the requirements
of the building and the range of options
available so that the most suitable solution
can be found. In pursuit of this goal,
professional advice is extremely valuable.
Metway Addressable Lighting
Control System
The simple, flexible and cost effective
solution for your lighting installation
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DSI / DALI
Fully addressable
Fully configurable
Programmable via Bluetooth
Can be controlled by optional head end PC
Can be integrated into an AV system
Side latching G type connectors
Visit us on Stand M7,
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3rd & 4th November 2016
Contact us for more information:
[email protected] | 01273 431600 | metway.co.uk
50-52 Lighting – Eaton.indd 52
Highly Versatile Range of
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Specially designed for use within harsh environments, the Waterproof range
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MANAGEMENT
SYSTEMS
Assessed to ISO 9001
LPCB ref. no. 653
EN54-11 Cert no. 653a/01
ReSet Series 01
13/09/2016 10:55