The only central overview of energy consumption at individual stores was provided by the supplier's invoices. Therefore, it was first necessary to find a way to accurately measure the consumption, down to the level of individual stores and even their different areas (sales floor, offices, warehouse, air-conditioning, water and gas consumption). The next step was to analyze the data gathered during the operation of all stores.
This analysis will help to identify stores with overly high energy consumption as well as ways of saving energy. In addition, the data will be normalized to determine the usual consumption figures per square meter of a store. Based on these figures, stores with higher consumption will be motivated to reduce it, or remodeled in order to save, for instance, on heating or lighting.
Several stores had to be equipped with newer types of electricity, water or gas meters with an M-Bus interface. A HWg-PWR unit was used to measure the consumption. This unit for metering the consumption of electricity, water and other utilities connects to external meters with an M-Bus interface. Up to 3, 12 or 25 M-Bus meters can be connected to one HWg-PWR unit.
Individual energy meters are third-party products. It is often possible to use those already installed at the customer's premises.
The HWg-PWR unit connects to a LAN. It provides a Web interface, and supports displaying charts, SNMP and Modbus/TCP output, data logging, e-mail and SMS alerts, and much more.
Measured data can be checked by the store management (online via the unit's web interface), and in addition, data from all units are centrally collected at the headquarters using the HWg-PDMS application and exported directly to MS Excel for further analysis.
- All energy meters are connected using the M-Bus (EN 13757) interface.
- Gas, electricity and heat meters are usually easily accessible at the store premises.
- There can be a central water meter only located outside of the store premises; in such a case, a supplementary water meter for the store can be installed.
- The HWg-PWR unit needs to be connected to 230V mains and to a LAN (Ethernet).
- Energy consumption of one store can be checked using the web interface.
- A central overview can be obtained for instance with the HWg-PDMS software for Windows, or with a suitable NMS/SCADA software package.
- Energy meters with pulse (S0) output can be connected to a M-Bus converter, or to a Damocles or an Ares units for indicative measurement.
Benefits for the customer
Thanks to the ability to analyze the consumption and trends at individual stores, first issues were identified after just a few weeks, such as stores that did not turn off their lights during the night, improperly heated or overheated stores, or possibilities to save energy by replacing certain appliances. Water leaks were also discovered, especially at toilets.
Collected data aided to the creation of standards for energy consumption, rules for using electrical appliances and guidelines for the staff to follow. Thanks to the ability to analyze the consumption at a particular store area in time, it was possible to demonstrate to the store management where and how is energy wasted and how to prevent it.
With accurate measurement and thorough data analysis, energy consumption decreased by 18% in the first year alone, and further decreases are expected after additional optimizations. This surpassed the customer's estimates when calculating the return of investment. To achieve this success, it was also important to inform the employees that the consumption is monitored and analyzed, and to reward individual actions towards reducing costs.
At this time, the customer is adding temperature, humidity and illumination sensors to the stores. With an analysis of individual environment parameters at store areas, heating and lighting can be even more optimized. In addition, there will be an option to control the heating and lighting remotely.
As of this time, the customer did not take advantage of alerts to exceeded threshold values that can be used to alert the shop management to any outages, failures or breakdowns.