Metering Systems

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MeteringWhen building a District Energy Scheme it is important to consider a metering strategy from the outset. Metering serves two purposes, the first is energy monitoring and the second is consumer billing/cost recovery.

If your scheme does not involve cost recovery, because it is a totally self developed/self contained scheme then the decision could be made to install a system which only provides sufficent information to monitor the energy consumed but does not require "revenue grade" metering. It may be that the choice is made to only install metering for monitoring purposes, becuase energy costs are apportioned on a floor area or unit (dwelling) basis, however schemes being developed using this approach are becoming increasingly rarer as it gives little incentive to the end consumer if their energy bill is not linked directly to usage.

For the energy generation plant itself, it is good practice, and typically a requirement under legislation such a the CHPQA program to install an energy input and output meter wherever practically possible for each piece for plant, i.e. a CHP unit or boiler. By continuous monitoring of these meters an energy balance for the plant can be obtained and deviations in efficiency compared to design levels can be quickly idienMeteringtified and then rectified. 

Typically there are two choices for linking the energy meters across a district energy network. The first is to link the meters to the LAN used for the building automation system controlling the plant in the energy centre. This is normally achieved by inputting pulses from the meters into the LAN (for each tranche of kWh or MWh passing through the meter), which can then be read remotely at the energy centre. Alternatively a seperate metering network (an MBuS) can be installed, particularly to retain the integrity/robustness of the metering system and return a greater amount of information from the meters (on temperatures, flow rates etc...) to the cental energy centre.