Submetering Strides

The level of sophisticated energy profiling needed by high-volume consumers is unobtainable using the standard meter found at the main utility service entrance. In response to the need for greater granularity, advanced submeters provide a cost-effective way to help facility operators identify literally thousands of dollars in reduced energy use and cost-savings opportunities.

Submeters, the primary energy data acquisition tool that allows building operators to do exactly that, are metering devices with monitoring capability that are installed on the facility side of the master meter to provide any or all of the following:

• Usage (kWh) analysis and peak demand (kW) identification;
• Time-of-use metering of energy sources such as electricity, gas, water, steam, and BTUs;
• Integration of lighting, HVAC, security and other systems into the building automation system (BAS) for a complete facility energy profile;
• Revenue-grade cost allocation used for tenant billing;
• Measurement, verification and benchmarking for energy initiatives, including LEED Energy & Atmosphere (EA) and Water Efficiency (WE) credits;
• Load comparisons;
• Threshold alarming and notification;
• Multi-site load aggregation and real-time historical monitoring of energy consumption patterns for negotiating lower energy rates, and more.

Submeters come in a variety of sizes, shapes and functionality, from standalone devices to multiple meter units (MMU) containing up to two dozen individual meters for a compact, easy-to-install solution to facility energy profiling needs. In the past, meter data was personally gathered by onsite “sneaker reads.” Later, phone modems greatly improved cost-efficiency and throughput. This was followed by sending data via Ethernet, wireless (RF) link, satellite, power line carrier (PLC) and other technologies.

All these methods are still in use to some extent, however the data itself is more complex and is now being used for real-time pricing and a host of other functions. New or improved metering products, coupled with new or modified communications options and protocols like Modbus, BACnet, LonWorks and others, continue to drive the technology toward greater value for the user. The Internet is now used to track and analyze “big picture” electrical consumption (kWh) and demand (kW) from a single circuit to multiple sites around the world.

In addition, the pervasive use of local area networks (LAN) in multi-facility residential, commercial and industrial applications creates new energy monitoring opportunities. Using the existing communications backbone eliminates the need for a modem and telephone line back to the central monitoring location and allows a full-featured Ethernet-based distributed submetering network to be installed quickly and inexpensively. Energy monitoring software allows users to read and monitor energy consumption and demand via on-site or remote, non-dedicated computer. Software allows generation of graphs and profiles of kWh and kW for demand analysis and usage reduction. Itemized bills may also be generated for tenant allocation and usage verification.

Submetering the multifamily space

Multifamily property owners looking to allocate utility costs back to the tenant, recover revenue and promote resource conservation, among other needs, are driving submeter deployment as a cost-effective alternative to arbitrary ratio-based billing measures, such as cost-per-square-foot, that do little to encourage energy conservation. Alternatively, tenants in high-rises, garden-style apartments, condominiums, co-ops and mixed-use buildings have been shown to consume significantly less energy when held accountable, by submeters, for the power they actually use. Accordingly, results of a 2009 study on multifamily residential buildings conducted by the New York State Energy Research and Development Authority (NYSERDA) confirmed savings of 18-26 percent.

In high-rise scenarios, submeters with interval data collection are useful for supporting time-of-use rate structures and reducing loads during peak demand periods. Other submetering benefits include:

• The ability to offer lower leasing costs due to improved conservation measures;
• Implementation of demand control to reduce energy use in common areas;
• “Shadow metering” of utility bills to verify accuracy and eliminate errors as well as  tenant disputes;
• Wireless metering may be unobtrusively installed in each tenant space for cost-effective, Internet-enabled monitoring.

Regulatory issues to watch

Advanced metering is a critically important element of compliance with Federal, state and local regulations and initiatives because submetering systems provide energy benchmark data, support measurement and verification of energy system performance and can help identify cost-effective measures relative to life cycle.

The Energy Improvement and Extension Act of 2008 (EIEA08) and the American Recovery and Reinvestment Act of 2009 (ARRA09) provide funding, block grants, significant tax credits, extensions and other incentives to jump start the move to more energy-efficient technologies. As these policies play out over time, submetering technology will continue to provide first-level energy data acquisition for benchmarking, measuring and verifying compliance with whatever program guidelines are instituted.

Many public-sector energy programs and executive orders are important to understand, especially the following whose controlling authority is foundational to most other current public-sector policy initiatives:

• Energy Policy Act of 2005 (EPAct 2005)—mandated metering of all Federal buildings by Oct. 1, 2012. Sections relative to submetering include 1251 (net metering) and 1331 (support for $1.80 per sq. ft. tax deduction for energy-efficient buildings).
• Energy Independence and Security Act of 2007 (EISA)—required by 2015; 30 percent reduction in total facility energy use relative to 2003 levels; natural gas and steam metering will be required by October 2016.

In the private sector, Standard 189.1, the “Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings,” claims to be the first green building standard in the U.S. developed for inclusion in building codes. Developed jointly by the American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE), the Illuminating Engineering Society of North America (IESNA) and the U.S. Green Building Council (USGBC), Standard 189.1 provides minimum guidelines for green practices for new commercial buildings and major renovations.

In addition to water management, energy efficiency goals include a minimum 30 percent reduction in energy cost (and CO2 equivalent) compared to Standard 90.1-2007. Submeters will play a role in Standard 189.1’s requirement for measurement devices with remote communication capability to collect energy consumption data.

First introduced in the early 1980s, submeters have evolved beyond simple metering functions into full integration with building automation systems to identify equipment performance problems, improve maintenance and operations procedures, drive behavioral changes that improve building efficiency and provide the fine-grained energy measurements that today’s increasingly energy- and cost-conscious multifamily facility operators demand.

Don Millstein is president and CEO of E-Mon, a manufacturer of electric submetering equipment, energy management software and AMR services in Langhorne, PA. A member of the Alliance to Save Energy, the U.S. Green Building Council, and the FEMP task force, Don participated in the Federal metering workshops that culminated in DOE/EE-0312.