Benefits of Sub-metering
Given the expense decades ago of purchasing multiple electric meters and the needed wiring, many multi-tenant buildings (both residential and commercial) have a single master or small number of meters to record electric usage. This leads to many issues, such as fairly assigning electric usage to specific tenant or operation and lack of motivation to conserve energy usage. If a building hosts a variety of tenant operations, it is likely one business or resident will pay more relative to what it is using (say, an office of any type compared to a restaurant). If you are paying a set percentage of the reading of the master meter, what motivation do is there to reduce usage?
Given the benefits and reduction in costs to do so, sub-metering is becoming an option many are considering. At least two cities, New York and Philadelphia, have promulgated laws to mandate sub-metering in certain situations. A recent report in EE Reports (www.EEReports.com) provides robust guides to the basics of sub-metering.
Perhaps the biggest argument for sub-metering is the eventual cost savings. If each tenant of a building has its own electric meter and learns what they actually use and have to pay for it, behavior (when it comes to energy usage) will change fairly quickly. The DOE has published the range of 5-15% savings in energy usage as tenants absorb the meaning of their high bills, realize they can now control their usage, and begin to implement simple strategies to reduce usage (more efficient equipment, not leaving on equipment, etc.). And these strategies have a short payback, generally under 3 years. A recent study in a NYC high-rise residential building showed 20% overall energy savings.
Planning for Sub-metering
Like many things with energy, this is not a matter of going out and quickly buying and installing meters and expecting great savings. Planning is important. Ideally, the building owner should research different types of sub-meters with different types of data displays, such as graphical, by time (hour by hour), or basic digital. Hour by hour is particularly powerful as it may identify areas of electricity usage you were unaware of, such as why is usage so high at night? Or why is it so high during a certain period in the workday? What equipment or department or group may be responsible? In addition, with many paying special rates for high demand during peak periods, hour by hour data can help you plan and verify that electricity-using operations are moved to non-peak periods, saving you tremendous costs on high peak demand charges.
Also, make sure that sub-meters that you procure be able to be checked and calibrated; that they are part of your measurement and verification (“M&V”) operations to ensure they are operating properly over time.
For more information
See www.EEReports.com for the full “Metering and Sub-metering 101” and “102” Guides and more unbiased information about energy efficiency.
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.