Energy conservation:. the application of standard energy conservation techniques at Crabtree Electrical Industries

Publication Date01 Nov 1995
AuthorT.J. Hughes,G.A. Bohoris
SubjectEconomics,Information & knowledge management,Management science & operations
The current literature has based cost savings on loosely
estimated mean costs of electricity and only touches the
surface of the problem of auditing equipment. Work that
has been carried out at Crabtree Electrical Industries
(CEI), Walsall plant, a medium size, vertically integrated,
light engineering company, has produced a relatively
accurate model of the compressed air system by
considering its operating characteristics and integrating
the appropriate tariffs into the model. The model has also
allowed for the further development of cost savings to be
considered and analysed and payback periods readily
calculated. The model does have limitations, mainly
owing to the several necessary assumptions, but has
provided accurate results. The methodology that has
developed is readily applicable to similar companies. The
need for complex modelling has been avoided through the
analysis of the total system and the medium size sub-
systems, rather than calculating each machine’s
requirements and using statistical analysis of machine
usage. This would have taken too long and have been
expensive to complete.
The work also involved electricity tariff analysis, an
integral part of the model. A brief discussion of the
competitive electricity market is also given which
identifies the necessary requirements that will enable
competitive bids to be received from the qualified
suppliers of electricity.
The air compressors have been identified from the initial
audit as the single largest consumer of electricity at the
site. The systems analysis showed that the total energy
consumption was significantly larger than the first audit
has shown. This identified that the total system was
inefficient and could be significantly improved by
replacement of equipment which would have the effect of
reducing the total energy consumption of the system.
The direct running cost audit
Taking into account Figure 1, the approach that has been
taken to auditing the energy users has been a step by step
approach which identifies system costs, rather than
individual users, in order to determine the largest
achievable savings. The audit has determined the largest
cost users of energy rather than largest energy
The audit involved the following stages:
meter identification;
working schedules/production patterns;
rated input;
actual usage of energy consumer;
energy consumer running characteristics.
This methodology has been used to enable resources to
be maximized so that time and effort is concentrated on
the areas which would benefit the most. It has been
assumed that the systems which incur the greatest
cost have the greatest cost-effective potential for
Meter identification
The historical readings of the utilities have been
obtained from recorded meter readings. Where no data
were readily available, the historical bills have been
audited to give aggregate meter readings over the
duration of the bill. In cases where there has been no
internal recording of the meters, or no meters in place, a
metering system should be set up which records the
consumption of each meter at least monthly. However, it
is demonstrated later in the article that understanding
of the load profile over a day rather than a month could
provide useful information, enabling the optimal tariff
Energy conservation:
the application of standard energy conservation
techniques at Crabtree Electrical Industries
T.J. Hughes and G.A. Bohoris
How standard energy conservation techniques can reduce operating costs and energy consumption
Industrial Management and Data Systems, Vol. 95 No. 9, 1995, pp. 9-16
© MCB University Press Limited, 0263-5577

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