How to cope with data overload (EiBI Article)

Control and monitoring of the energy consuming systems connected in a building allows the end user to manage the building and control energy usage a lot easier than by manual intervention.

A BEMS is no longer limited to hard-wired integration of these data points and is now open to much more information.

With the current prevalence of BEMS software integration with the buildings plant and equipment’s own packaged control systems (via BACNET, Modbus etc), the amount of data available for the BEMS to utilise is now enormous.

BEMS software integration is available via a single hard-wired data cable which opens up a vast array of data.

The plant and system manufacturers are increasingly providing their own proprietary packaged control systems with inbuilt BEMS interfaces. They open their packaged controls up for integration and make every single internal data point available for reading or writing by the BEMS.

Use critical data
In some instances this data is critical to the operation and maintenance of the plant and affects the way the BEMS controls or manages the equipment. This critical data should be integrated into the BEMS and used as necessary obviously on the basis that software points do not replace essential hardwired interlocks! It is worth emphasising that a software data point is no substitute for an important hardwired signal such as fire or CO alarm.

"Supplying energy metering data should be tailored to the end user’s needs"

Once the critical or useful data is identified and used, you are left with many internal software points available that may mean something to the plant or equipment manufacturer when carrying out a service or maintenance but are not useful to the end user or the company managing the building.

For example, if a BEMS reports a chiller is in ‘fault,’ the end user would use this information to contact the relevant specialist to contact the correct specialist supplier. The chiller specialist would then attend site to identify the fault and rectify it regardless of the amount of additional data on the BEMS. The data being displayed on the BMS is useful to no one apart from the chiller engineer who doesn’t need it as he would be using his own fault diagnostic software when attending site.

This additional plant data still needs to be processed, displayed and stored by the BMS which incurs additional cost through additional BMS hardware and engineering time. For data that is not needed or used it is a cost that could be saved.

BEMS data overload point
The BEMS data overload point is well illustrated by considering the monitoring of energy metering data on a BEMS. As we know, energy sub metering is an essential tool in any energy management and saving plan to allow the size and scope of the energy consumption within a building to be identified, measured, overuse actioned and then validated. A well-installed and thought-out energy metering installation covering a recommended over 90 per cent of the buildings energy usage is essential.

However in terms of data overload, it can easily lead to large amounts of data being unused. For example a MODBUS electric meter will provide a myriad of datapoints covering kWh, kW, amps per phase, volts per phase, kVAR, PF etc., via a MODBUS interface.

Superfluous information
If the end user is simply interested in measuring a kWh saving or reading to validate an energy project of maintain a base line, the rest of that data is superfluous and not used. There is no need to read, display or store the additional data on the BEMS.

Supplying energy metering data to the end user should be tailored to what they need the data for. This can be done by a simple discussion or RFI exchange.

To avoid this data overload, consideration should be given right at the start of a project to how that data is going to be utilised and in what format is it needed i.e. graphical interface, data file, local HMI etc. The data needs to be relevant to the end user or else they will not use it.

With project costs being a constant focus and businesses being asked to put forward value engineered options the cost for additional hardware and software to process needs to be considered. The specification and design of a BEMS system needs to take into consideration what is required from an operational aspect which is critical and then overlaid with what the end user wants to see.

With this defined the end user will have a system that not only operates efficiently but is more specific to their requirements without the overload of data.

To keep the amount of data relevant to the actual end user the following three steps should be followed:

• Understand the end user’s requirements from the start;
• Implement the BEMS to suit the end user through bespoke design (software and hardware); and
• Instruct the end user on how to access and use their data.

Following these three steps will not only reduce overall project costs via a reduction in hardware and software engineering but will also make the data more useable and user friendly for the end user in their chosen display format. Only import data into a BEMS if it is relevant and useful to the person looking at it.

You can find the rest of the April edition of Energy in Buildings & Industry publication here.