6B — February 22 - March 14, 2019 — Environmental/Green Buildings — Owners, Developers & Managers — M id A tlantic
Real Estate Journal
www.marejournal.com
E nvironmental /G reen B uildings
By Nicole Paul, Energy Management Systems, Inc. Combatting reduced recovery rates based on water meter degradation
W
ater meter degrada- tion can be defined as the need to re-
decays over time. For instance, a study done by the Water Engineering andManagement Journal, explains that meter accuracy degrades rapidly on average after 20 years, falling from a real meter accuracy of 99% down to 82% by year 30. In addition, the size of the meter in relation to aggregate flow-through volume can cause problems, as smaller meters with low flow rates result in the highest degrees of inac- curacy. There are three specific fac- tors to focus on when analyz- ing meter degradation and the reasoning for this occurring:
Age, Rate of Degradation and Low Flow Rates. Accuracy degradation only in low flow scenarios for a 20-year-old meter according to Dr. Hans Allender, P.E., may be as high as 40% degradation or the me- ter may be only 60% accurate. In addition, there is also the issue of renewing the meters too often that will produce economical losses caused by the fixed costs of the invest- ment. To solve this issue, you must either test every single water meter in the system, to exactly determine the average performance at different flow rates which can be costly or
rely on statistically represen- tative samples of each type of meter. It is also important to determine water meter weighted accuracy with the average water consumption pattern, which gives informa- tion about how much water is used at different flow ranges. The weighted accuracy is the parameter used to estimate the total unmetered water vol- ume over time and the optimal replacement frequency of me- ters (Residential Water Meter Replacement Economics). One excellent example of water meter degradation would be when EMS replaced the water meter set at a prop- erty for a national REIT. The national REIT water meters were experiencing exceptional recovery rates in the two months after meter replacement and exceeded the two months prior to meter re- placement by an outstanding 37%! This example further reinforces the idea that water meter degradation occurs and that there are benefits in cost recovery when the meters are replaced. In addition, it sup- ports the assertion that this national REIT has an opportu- nity to greatly increase its re- coveries through water meter replacement, in addition to the operational benefits of a con- version to full AMR readings. In conclusion, building owners should pay close attention to the age of their meter, and get them replaced with newmeter equipment or read with AMR to avoid inaccuracy of meter reads and tenant consumption later down the line. Nicole Paul is a market- ing communication spe- cialist with Energy Man- agement Systems, Inc. References: Allendar, Hans, Dr. Determining the Economic Optimal Life of Resi- dential Water Meters, Water Engineering and Management Journal, 1996 Arregui, F.; Cabrera, E.; Cobacho, R.; & Garci-Serra, J., 2005. Key Fac- tors Affecting Water Meter Accuracy. Proc. Leak- age 2005, Davis, S.E., Residential Water Me- ter Replacement Economics, Leakage 2005 Conference Proceedings, 2005 1 In 2001, the Water Research Foundation (WRF) published the results of an extensive four year a re- search study, “Accuracy of In-Service Water Meters at Low and High Flow Rates” 2 Noss, R.R.; Newman, G.J.; & Male, J.W., 1987. Optimal Testing Frequency for Domestic Water Me- ters. Jour. Water Resources Planning &Management Div.—ASCE. 113:1:1.
over time. Studies date back to 1987 by G.J, Newman, when the water utility industry began to document the suscep- tibility for older water meters to suffer degraded accuracy and under-reporting of actual consumption. Water meters are not able to exactly register the total amount of water consumed since they have a limited range of operation. Its perfor- mance normally diminishes at low flow rates, which are in most cases due to leaks in the user’s facilities. This problem increases with water meters aging since the accuracy curve
place exist- i n g wa t e r meters with new meters due to under- reporting of actual tenant consumption and l owe r flow rates as-
Nicole Paul
sociated with the meter types aging. Rapid amortization of the investment is based on the advanced age of the target wa- ter meters and the propensity for older meters to degrade
Improve Sustainability, Energy Benchmark Your Property New York, Philadelphia, Washington, D.C. Contact us: 202-525-8475 » www.ems3.com
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