We always fit energy loggers to record out-of-hours electricity consumption as part of the energy review carried out to implement the ISO 50001 Energy Management System. The results, as might be imagined, were very mixed but on several occasions the logging equipment revealed some alarming instances where the non-working hours demands when the building(s) are unoccupied were not massively different from the working hours demands.

The chart in this article illustrates one example of one of our energy loggers monitoring the air conditioning consumption on just one floor of a six-storey office building in North London.

The blue coloured rectangle highlights the electricity consumption between 7pm and 6am and reveals that nearly 300 kWh were consumed by the air conditioning system for maintaining a set point temperature of 19.0 degrees Celsius in the offices despite the building being unoccupied.

By extrapolating the result by the number of non-working hours per year the estimated wasted energy amounted to a staggering £16,640 per year and that was on just one floor of the six-storey building.

Further investigation of the air conditioning system revealed that the timer function on the local controllers appeared to have not been setup since the split ac units were installed several years previous.
Occupancy sensors that may be purchased as an optional extra from the suppliers or even retrofitted also have the effect of switching off the air conditioning when no people are detected and can help towards making a further big dent in energy bills.

The findings of the energy audit reinforced our observations made under the ESOS regulations that significant improvement in energy performance can often be achieved with little or sometimes no capital investment being required.

Mike Glanfield
Chartered Energy Manager
Epsilon Energy Professionals
0800 779 7414
www.epsiloniom.com