Energy Management 101: Smart Submetering and Data Logging

June 25, 2014

Wish to be an energy whiz? Deploy devices that cut consumption, balance baselines, and revitalize reliability.

You can’t manage what you don’t measure. And if you’re measuring your building up against today’s efficiency pacesetters, then data logging and submetering can take you the extra mile. Data loggers and submeters will dive into greater detail about your energy consumption – more than a utility bill can ever hope.

You can learn about usage on a floor, system, or fixture basis. Having this kind of granularity leads to small steps that can yield great strides.

On topic: Set Building Management System for Energy Conservation Success

First consider why and how you’ll best utilize these strategies, and then focus on slicing down the two biggest sections of the energy pie: HVAC and lighting. Unless you’re converting the data into actionable items, a logger or submeter is no more useful than a garage opener – which is about as easy to use. Read on and learn how to best utilize these new trinkets in your energy toolbox.

Motivation and Methodology

When confronting cutting-edge, tech-heavy strategies, some FMs face quandaries. But the two most important questions to ask are why and how.

“Knowing what to do means making predictions with less ambiguity and uncertainty,” says Matt Ganser, Director of Engineering for Carbon Lighthouse, a firm that helps clients achieve carbon neutrality. “That answer is data.”

Facilities professionals want to reduce costs, keep occupants happy, and optimize equipment performance. Achieving these goals requires knowing the building’s pulse, and you can take it with loggers and meters.

“Recording actual energy usage at a more granular level can also be used to allocate specific costs to tenants based on their consumption,” explains Gregg Dixon, senior vice president of sales and marketing for EnerNOC, a provider of energy intelligence software. “Compliance with certain green building initiatives and certifications may also require submetering.”

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Once you’ve addressed the motivation behind your deployment, you can move on to the method of performing it.

“A caveman couldn’t do it, but basically any person can launch and deploy a couple loggers every minute. The technology shouldn’t be a barrier,” Ganser says. “The trick is knowing what to measure.”

In addition to energy consumption, loggers and meters can record temperature, humidity, carbon dioxide, water use, light levels, and several other metric. For most applications, intervals of 15 minutes over a one-month period are sufficient.

The devices can be secured via magnetic backing or duct tape. Make sure they are in secure locations that are out of the way. Ask staff, security, and tenants not to move them. “Tell them they’re part of an intensive energy investigation,” recommends Ganser.

Your device will either feed into a central logger/meter or connect to a computer or tablet via the Internet. Using the provided interface, choose a common start time for all devices and give each one a specific name. “A tip is to use a unique signifier based on location,” Ganser suggests. “Don’t just call it ‘temperature.’”

Related: Internet of Things: How IoT Devices Enable Predictive Maintenance

Have a working hypothesis at deployment. Think about when certain equipment should run and when the building is occupied. Consider if an environment is stuffy or drafty. Ask yourself what you’re specifically looking for and what you’re trying to prove. If you’re skeptical of system performance, your suspicions will likely surface in one of the following two areas.

Hasten HVAC Headway

Temperature impacts occupant comfort, equipment performance, and your utility bill. You may think your thermostat can capture a snapshot of it, but it’s only providing a tiny part of the picture. First, you must account for the difference between fluid and air temperature, and the latter splinters further into outdoor, return, supply, mixed, and zone air readings.

“Luckily, temperature is pretty easy to measure,” says Ganser. “You have your general feeling and you can go out and get spot readings with infrared guns. But data loggers give you continual measurements over time.”

Read next: How to Get the Most out of Your Air Filtration System

Let comfort be your first clue that your system may be out of whack. Comfort is a fairly large zone, and humans are relatively adaptable, but if we’re outside of our zone, we notice it. Complaints are often a symptom of poorly controlled equipment and thus unnecessary utility and maintenance costs.

Temperature’s ugly cousin is humidity. Highly humid areas may indicate poor ventilation or low cooling capacity. Your device can also be programmed to track humidity percentages, which can be as helpful as temperature readings in certain applications.

“Think about temperature and humidity in terms of building management systems,” says Ganser. “An automation system controls your building using temperature set-points, but faulty or disconnected sensors may not trigger an alarm. If you’re not logging that data, how would you know of the defects? Incorrect inputs lead to comfort issues, unnecessary equipment wear and tear, and high utility bills.”

Common deployments involve monitoring:

Discharge air temperature from the ceiling
Fluid temperature in pipes
Supply air temperature in the plenum

Enliven Lighting Practices

Data loggers and submeters can motivate lighting system upgrades, which include primary drivers like reducing energy use, cutting operations and maintenance costs, and improving quality and control.

Utilities provide incentives to reduce upfront cost for lighting upgrades, as do some state and local governments (visit for a list). Performance contracts require no upfront capital because they’re paid off with savings. But to utilize these funding methods, you must demonstrate performance with measurement and verification, explains Mark Stetz, owner of the firm Stetz Consulting LLC.

“The goal is to provide equivalent or better light levels with less energy,” he says. “With these devices, you can measure existing levels for a before-and-after comparison and track power usage and operating hours.”

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The product of power and operating hours establishes your baseline energy use, Stetz adds. “Power is the slightly more important parameter because reducing it defines energy savings potential,” he explains. “But hours are also important because there is significant uncertainty about when a facility is actually operating. There could be thousands of hours of opportunity per year.”

Measuring your current system should reveal low-hanging fruit opportunities for savings. Lighting loggers can record status (on/off), occupancy, and light levels (for recommended illumination in different applications, visit If a space is unoccupied but the lighting is on, there is potential for savings.

Beware that loggers and meters cannot differentiate between natural and artificial light, Stetz warns. Two to three weeks of monitoring is typical for lighting deployments, he adds, but avoid major holidays and skip safety-wired fixtures near exits, which may remain illuminated continuously.

“The data evaluation will reveal how big the potential for savings is,” says Stetz. “It will help you make the business case for an upgrade.”

Success Stories at a Glance

Deploying data loggers doesn’t have to be a facility-wide effort or an intensive project.

Discover what focused strategies can achieve:

  • At a gym in San Francisco, CA, the property manager heard that the space was warm but didn’t think the complaint was reasonable. Loggers were used to measure outdoor air temperature on the roof and zone air temperature in the space. They revealed that the system’s economizers were failing to bring in cooler outdoor air and were instead recirculating return air, explaining the stuffy interior feeling.

  • A fitness center in San Jose, CA, had severe comfort issues due to stickiness and heat. Loggers measured zone air temperature, relative humidity, and CO2 levels, which far exceeded code limits. Along with high temperatures and 60-70% humidity, this indicated poor ventilation and a lack of cooling capacity.

  • At a community center in central California, the building management system indicated that a boiler was enabled when it was actually off. Although there were no temperature complaints, this was troublesome. Loggers of outside air temperature and on the boiler revealed poor relay wiring and faulty sensors that failed to disable the hot water system. The pump and boiler were on with temperatures well over 90 degrees F., resulting in significant energy waste.

  • Economizers were designed to provide free cooling at a community center in Sacramento, CA, but loggers revealed that the mixed air temperature was almost equal to that outdoors. This led to the theory that the dampers were completely open at all times, which was confirmed visually. Fixing this situation helped maintain more constant return air temperature and earned utility savings of $2,400 per year.

*Source: Carbon Lighthouse

Ruminate on Your Results

Remember that your data gathering must lead to actionable items in order for your efforts to be effective. The moves you make after analyzing the data will produce a kind of indirect return on your devices.

Energy management consultants have proprietary programs for graphing and calculating what to do next. System manufacturers such as Onset, EnerNOC, Eaton, and Perillon also offer this work. But you can do a lot of it on your own.

“All you really need is Excel,” says Ganser. “The Universal Translator from the Pacific Gas and Electric Company is also an amazing resource.” 

Your first major concern should be plotting your energy curve and lining it up with occupation, says Dixon. “Things should start up when you need them to and power down when they’re not needed. It sounds simple, but it’s not,” he explains. “A supermarket may program its lights to turn off an hour after close, but if the stockers and cleaners aren’t done yet, they override the system. Then it could be on all night and how would you ever know?”

The second area to consider is your operating parameters or triggers. If equipment is cycling to maintain a certain range, it’s wasting energy and experiencing needless wear and tear. Scheduling may alleviate this issue.

Read also: Machine Learning: 5 Steps to Optimize Your Facility with Data Analytics

“Scheduling is also helpful if some utilities have varying demand charges,” says Dwayne McGrody, product manager with Eaton. “If you know when the charge is highest, a meter can tell you if equipment is on a lot during that time and help you know if you could power down certain components. A bill can’t tell you what happened, when, or why.”

Above all, data loggers and submeters can make your life easier by taking the guesswork out of complicated energy functions.

“Deploy these strategies in a proactive manner, then act on them,” advises James Jensen, vice president of products and services at Perillon. “The system tells you when there’s a problem, and then you engage in a directive. Let it do the thinking for you. It tells you when you need to worry – until then, focus on all your other responsibilities.”

Case Study #1: Morgan Stanley, New York, NY

Morgan Stanley, New York, NY - strives to maximize energy efficiency.*Photo Credit: Anatoliy Lukich


As the owner and sole occupant of a 1.3 million-square-foot building in midtown Manhattan, Morgan Stanley strives to maximize energy efficiency. In 2009, the firm conducted a full retrocommissioning of its headquarters.


Fearing that efficiency gains from the retrocommissioning effort would be lost without continuous careful attention, the firm took steps so the building didn’t drift gradually out of optimization. Identifying ongoing opportunities to increase efficiency was of utmost importance. The goal was to find actionable improvements with short paybacks.


Morgan Stanley gathered energy use from more than 9,000 points throughout the building. A portal provides baseline performance and granular, real-time trended data. These insights fuel monthly energy scorecards the firm receives from the system supplier, as well as strategic advice about capital investments and daily technical adjustments.


Opportunities for energy savings included regulating night-time setpoints on Morgan Stanley’s trading floors, optimizing the sequencing of chillers, adjusting heating and cooling cycles, and streamlining lighting efficiency. The changes have not affected employee comfort or productivity.

Based on utility bills, Morgan Stanley saved over $125,000 in the first year and a half of energy monitoring. In addition to reducing its carbon footprint, the firm also enjoys benefits of ongoing operational proficiency, seamless collaboration among executives and staff, and a continual fostering of new efficiency insights.
*Source: Enernoc, Inc.

Case Study #2: University of Notre Dame, Notre Dame, IN

University of Notre Dame - invested over $10 million to reduce campus
energy consumption by 10% since 2008. 
*Photo credit: Nagel Photography


To combat high energy costs – university FMs typically spend between 35-50% of their operating budgets on energy – the University of Notre Dame has invested over $10 million to reduce campus energy use by 10% since 2008.


“Electricity consumption is traditionally metered at the point of service and nowhere else. It makes detailed analysis difficult,” says Paul Kempf, the university’s senior director of utilities and maintenance. In order to know if conservation strategies would be effective, the school needed a measurement and verification system.


To monitor, control, trend, and alarm electrical issues across the campus’s high voltage distribution network, the university installed solid-state electric metering. The goal was to work toward a centralized energy management system that tracks the consumption and performance of multiple buildings.


In addition to meeting its campus-wide target, Notre Dame challenged students to realize a 10% behavioral reduction in energy usage in residence halls. Through a series of competitions, students also chase the goal by utilizing a web-based application that provides real-time results for their efforts and instills a culture of conservation.

Other savings come from enhanced electrical system reliability and reduced maintenance costs. Metering also enabled Notre Dame to perform rate scheduling based on the voltage level at which power is purchased, time-of-day usage, interruptible power plans, and reactive power usage.
*Source: Eaton Corporation

Case Study #3: Travis Air Force Base, Fairfield, CA

Travis Air Force Base, referred to as the "Gateway to the Pacific." *Photo credit: Anatoliy Lukich


Referred to as the “Gateway to the Pacific,” this site handles more cargo and passenger traffic through its airport than any other military air terminal in the U.S. It features a museum and 265-bed teaching hospital.


Under Presidential Executive Order 13423, this site is required to achieve sustainability and energy efficiency to the maximum extent possible. Its design elements include solar orientation, daylighting, high efficiency equipment and fixtures, and the use of sensors, controls, and energy management systems to reduce consumption.


Energy managers were trapped in manual data collection with no tracking of consumption by individual assets and no workflow to implement measures. Travis Air Force Base installed a cloud-based workflow automation system to increase granularity, centralize collection in one location, and provide alerts, alarms, and tasks.


As data enters the system, it is compared against an allowable range or permitted limit of consumption. If the range or limit is exceeded, alerts are issued along with regulatory mandates necessary to restore compliance.

Each task is assigned to a specific employee, tracked to completion, and escalated if not finished on time. Various reports can be generated to detail activities, provide management with results, and confirm goal attainment. The smart meter system achieved ROI in a little over one year.
*Source: Perillon Software, Inc.

Chris Curtland was an Assistant Editor of BUILDINGS.

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