Since the introduction of the Heat Network (metering and billing) Regulations 2014 there has been a marked increase in specifications that include a way of apportioning energy consumption for energy billing. The idea of such apportionment is that the landlord can bill tenants on the basis of actual energy usage, rather than simply dividing the total energy costs between the number of tenants.
There are clear advantages to this development in energy billing, not least because it’s clearly fairer than simply ‘divvying up’ the bill. Also, if individual tenants have a clear understanding of their energy consumption they are able to take measures to reduce it – in keeping with the ‘Soft Landings’ concept.
However, in many cases the process of apportionment for energy billing is complex and time-consuming. Specifiers therefore need to consider just how the apportionment will be achieved and include mechanisms to make it as easy as possible.
Perhaps the most important systems in this respect – because of their energy consumption – are the hydronic systems that provide heating and cooling in many commercial buildings – such as fan coil and chilled beam systems.
Granular detail of energy consumption would certainly be provided by fitting a meter on each terminal unit but this would be very costly and generate unmanageable volumes of data. At the other end of the energy billing scale is the option of metering each system centrally but this is of no help in multi-tenanted buildings as it only provides a coarse overview of energy consumption by the whole building.
A happy – and effective – compromise for energy billing is to meter the terminal units in zones, with each zone being served by a commissioning module connected to a number of terminal units. Each commissioning module is fitted with a data logger to allow energy metering of each zone of terminal units – so that if the zoning reflects the configuration of tenants’ spaces it becomes straightforward to measure how much energy each tenant is using for heating and cooling.
A further benefit of this arrangement is that the use of commissioning modules connected to terminal units with flexible pipework makes it very easy to re-configure zones if there is a change in layout.
Optimising energy consumption
Moreover, this approach to energy billing can make a significant contribution to energy management, by incorporating an energy meter in each commissioning module. The device will continuously monitor flow rates and provide data through the building management system so the building operator can assess the performance of each zone. Such devices will also continuously monitor the Delta T across all terminal units to ensure efficient operation and support maintenance of the system.
With this arrangement, the building operator or energy manager then has very easy access to real-time performance data about the heating and cooling systems on a zone-by-zone basis. Further analysis can remotely provide individual terminal unit data. This enables them to identify any areas that are not performing efficiently and implement appropriate remedial measures, while underpinning accurate billing of tenants or departments for their energy consumption.
From a facilities management point of view it also provides reassurance that set-point temperatures and comfort conditions are being maintained within each space, even when some of the occupants may think otherwise.
All of these considerations are addressed in the design of SAV’s FloCon Watchman system.