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Energy reporting system approaches in commercial buildings

Posted by efficiencydirect on August 5, 2016

There is no standard approach to creating a buildings energy reporting system. This is because each building will have a varying degree of sub metering installed within.

This can range from no sub metering at all to a completely comprehensive sub metering system monitoring the various supplies throughout the building.

There is therefore no set way of creating the energy reporting system and there is a certain amount of knowledge required to adapt the existing building metering into a fully functional energy reporting system.

These varying degrees shall be discussed in more detail.

Undertake a building metering survey

It is imperative that a site metering survey is undertaken by an energy consultant to determine the extent, type and condition of the metering and sub metering within the building.

It should be determined how the site is currently using the metering and sub metering within the building for energy management.  The usual situation is a varying degree of manual reads being taken on a monthly basis.

The way to approach this is to initially look at the tariff meters. It should be determined if there is any AMR on the electricity and gas tariff meters. If there is, the data should hopefully be available to be used within an energy reporting system to monitor the buildings energy at a high level. This would normally be held by the supplier, and it is them who should be approached to access the data.

Initially, monthly energy reports could be produced at this stage, using the half-hourly electrical data and AMR data from the tariff gas meters.

The metering survey will highlight the degree of sub metering within the site.

This could consist of:

  • No sub meters installed at all.
  • Sub meters installed and stand-alone from any other system.
  • Sub meters installed and connected and reporting to a BMS.
  • Sub meters installed and connected and reporting to a BMS energy reporting system.

If No sub meters are installed

A strategy should be established of where sub meters could be installed to monitor the supplies that are deemed to be important energy drivers within the building, this could include chillers, AHU’s and other important plant.

Floor sub meters should also be considered for installation if the building is intended to be monitored at a lower level.

This could also be considered if tenant metering is required to charge back energy consumption on any tenant floors. MID (Measuring Instruments Directive) sub meters should be installed if this is the case.

Tenant supplies directly from the LV room should also be considered and factored into any tenant charge backs.

The practical and cost implications of where the sub meters and loggers will be fitted should be considered, it could be easier to concentrate the sub metering within the LV room.

Access through risers and the practical size and configuration of floor riser cupboards should be considered. The siting of sub meters within plant rooms or LV room LV boards should also be investigated.

Once the sub metering strategy has been worked out, a proposal with cost should be submitted.

The energy reporting system being used should be considered during the strategy stages. The requirement and what is expected from the system will need to be considered i.e. does it have a tenant metering charge back facility if this is required. Again, it will also affect the overall cost of the sub metering installation.

Sub metering installed and standalone from any other system

Many buildings can already have a sub metering system incorporated into the building from the build. Very often, it is totally stand-alone and not connected to any sort of energy reporting system.

If the metering is being used for energy reporting, it is usually through monthly manual reads. This is a very basic method and liable to inaccuracy and will not be able to show any energy graphical profiles. It will only show a total of consumption between the reads.

Again, a survey of the sub metering system and its condition should be undertaken and a strategy should be undertaken to determine what the sub metering is monitoring. It should also include any other sub metering that is required.

An energy reporting system should be chosen to connect to the sub metering system so that the data can be collected and logged.

The requirements of the energy reporting should be considered, i.e. Is it required to provided tenant billing, if so an energy reporting system that provides this facility should be chosen.

The sub meters being used for tenant metering should be checked that they are MID (Measuring Instruments Directive) approved.

Sub metering installed and connected and reporting to a BMS

This is quite common within many sites, and if the building is relatively new it is now part of the required fit out. Very often, gas and water as well as the electrical sub meters are also included. However, it is the usual situation that the sub metering takes a second preference to the actual control system and sometimes isn’t set up or commissioned correctly.

There is usually a sub metering page on the BMS headend that only shows the count up of kWh energy consumption, from the moment the supply was switched on. It is therefore only a kWh total value. There is therefore no historical data as there is no logging facility associated with the sub meters. The sub metering on the BMS is therefore visual only and energy management can undertake by manual reads from the BMS headend metering page or the sub metering itself. A full validation of the sub metering system should be undertaken, to determine its extent and accuracy.

The solution to creating an energy reporting system is to connect a propriety system to the BMS. There are different versions that can be chosen and the choice depends on the requirements from the energy reporting system and the cost.

The data from the sub meters is logged on the BMS or a connected device and is usually accessed locally or remotely from the chosen energy reporting system.

The energy reporting system is then used to create the required energy reporting usually in the form of graphical images and statistics depending on the requirements.

Sub meters installed and connected and reporting to a BMS energy reporting system

If a building already has an installed sub metering system and it’s connected to an energy reporting system (possibly via the BMS), an investigation into its extent and a percentage validation can be undertaken to determine its accuracy.

If the validation proves the energy monitoring system to be working and logging the data accurately, it should be used to provide energy reporting for the site.

The sites energy reporting system will be the major tool to reducing energy consumption if it is managed properly and any abnormal consumption is reported and investigated.

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