Opening Up Energy Management
Tyler, Geoff, Management Services
Last summer Geoff Tyler looked at the economies in choosing electricity, gas and oil suppliers carefully. He now turns to the management systems helping us to use it efficiently.
As I write, the late January snowfall seems to make it appropriate that I should be looking at energy management and monitoring systems. Capable they certainly are, but there could have been more progress by now to allow greater control and freedom of management services' style.
There are two sides to the question. One needs to use control equipment which, by various sensors and automatic responses, can keep power consumption to a minimum and comfort, operating efficiency etc to a maximum. And one needs to have detailed data to know how well those measures are working - and that they are being applied in the right places.
At the sharp end, of course, all plant management systems need data from thermometers inside work areas, automatic information on the occupancy of an area for heating needs and such. Other things like automatic control of air conditioning to avoid needlessly treating air which is still cool and fresh add to the capabilities. Among the aims is to remove from the suspect world of staff discipline the measures needed to make every possible economy. People leaving a room simply cannot be guaranteed to turn off the lights.
There are howlers, however, as Steven Henry of Chalmor Ltd mentioned to me. `Most common, perhaps is that time clocks on plant are not adjusted to keep up to date with changing work practices. Another error concerns the frost-stat. Its job is to maintain the heating at low level when outside temperatures show that pipes could freeze, so the stat is commonly placed on the north exterior of the building. This may be the coldest part but is not where the pipes are installed. Frankly the outside temperature is irrelevant provided the building is reasonably insulated and pipes lagged. The inside temperature near the pipes is the important figure.'
He goes on to advise using electronic tamper-proof thermostats which staff cannot abuse, more precise plant switching controls sensitive to prevailing weather and temperature conditions, temperature profiling for working and non-working hours, allowing for heatgenerating machinery, using or isolating solar gains, infra red sensors controlling light switching and plenty more.
Not universally recognised is that the building regulations now require that buildings using more than 1OOkWE of heating must have some form of optimisation control. 100kW would heat an office of about 600 sq metres. Just what is acceptable as an optimisation control varies with building inspectors and, one suspects, advances in technology making more capable systems available. A simple time clock on the boiler, however, is not good enough.
The conventional view of energy controllers is one of dumb terminals on-off switches, simple thermostats etc perhaps being instructed by a central computer based intelligence.
Systems are now moving toward intelligent controls on heating and air conditioning plant and on internal climate control equipment (automatic blinds, local area heat vents and so on) which are networked into an energy control system. That system then has overriding management software for more co-ordinated and sophisticated operation than a central system alone could achieve.
Maurice Eyke, managing director of Ambiflex Ltd., praises the progress which has been made:
'Microprocessor based controllers now have much improved information displays and system access tailored to the needs of the different levels of users - programmer, commissioning engineer, plant engineer and caretaker. We are now starting to see low cost upgrades in system capacity by firmware changes. Improvements include control routines, for example for variable boiler sequencing to increase boiler time off as the return temperature gets closer to the target flow temperature. …