Two months ago I posted a blog article on sub-metering and its many benefits, such as providing a fair measure of what different users use in terms of electricity and other utilities in order to avoid or to resolve landlord-tenant disputes and to get real readings to encourage energy and water savings (when people see what they really use, they readily invest in technologies to save). At least two cities, New York and Philadelphia, have promulgated laws to mandate electricity sub-metering in certain situations. A recent report in EE Reports (www.EEReports.com) provides robust guides on the basics and how-to of sub-metering.

OK, you have agreed with the arguments that sub-metering will lead to eventual significant cost savings and avoid disputes before they start. There are 3 steps to implement sub-meters, as follows:

• Site Survey. Review drawings and walk the site to understand the layout and the site’s needs. Decide what you wish to sub-meter for. Electricity (the most common) only? Gas, water, other utilities, too? Have in mind the reason(s) you are sub-metering (M&V, demand response, cost allocation, optimizing building performance, and/or bill verification). How many sub-meters may you need, a number based on the number of tenants? Generally one sub-meter can accommodate one single phase or three-phase load and up to 7 connecting wires. An important item to consider is how will the sub-meters interface with your current (or perhaps future) building management or automation system. Wireless? Ethernet? Proper planning is so important.

• Commissioning. After installing your sub-meter (by a certified, experienced electrical contractor), don’t have the attitude of “set it and forget it”. You’ve invested the money and time; make sure the sub-meters provide reliable, accurate, accessible data. Compare values from the sub-meter with that of data measured by BMS software. Take 2 readings around a desired timeframe (ex. 1 hour apart) to determine usage, and compare. Take multiple readings in time. If the sub-meter readings are significantly different, then contact the vendor and/or installer to determine why. It could be faulty wiring or a faulty sub-meter. Perhaps a different model or type of sub-meter is needed to handle the load.

• Evaluate your savings. Now that the sub-meters are installed and operating, collect data to show how the electricity, water, etc. is now distributed among tenants and compare it to past readings (before the sub-meters) to determine long-term savings. Determine usage trends and tie them to location, time of day, building activities, etc. See in what areas your building can focus on to take the greatest advantage in terms of tenant leases, demand management, etc. Are the promised savings being met? Repeat these evaluations at least every year to see how the sub-meters continue to operate and to save your building money.

See www.EEReports.com to see the full “Metering and Sub-metering 101” and “102” Guides. CCES can help you assess the value of sub-metering your buildings and can plan and manage its complete implementation to maximize your financial benefits. Contact us today at 914-584-6720 or at karell@CCESworld.com.