To integrate building systems for sustainability, you have to consider people as the most important node in the system. My feedback systems course in college didn’t mention people, but a number of the presenters at the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Existing Buildings in Urban Areas Conference did. I think it should be added to the curriculum.
“Focus on the effects on people, not buildings—that’s how enormous savings can be made,” said Thomas Hartman, the Hartman Co., an heating, ventilating, and air conditioning engineering and technology development firm.
He emphasized the importance of performance-based design. He also stressed that the advantage of evaluating an existing building is that you can base it on actual practice rather than a theoretical design.
In order to incorporate people into the feedback loop, you have to consider the interface between the physical and human systems. Michael Byrnes, Source One, discussed that interface: the metering infrastructure. Among his key points was that the meter must provide useful information, which means more than just a monthly total. Of course, it needs to accurately measure the energy used. The important word is “accurately.” If a submetering system is installed and not accurate, the results are meaningless, especially since submetering is used to track relative energy usage throughout a building. A small wiring error can produced skewed results.
More about meters:
• Ideally, the meters should be installed by electricians who understand the system and are commissioned by a qualified metering system company.
• The meters should provide data for the amount of electricity used during preselected intervals. Scheduling readings during finer intervals allows for a more detailed analysis.
• The meters should be able to communicate the data they collect using an open source protocol—the most basic, simple and universal data source is a dry contact pulse output where one click equals 1 kilowatt.
The best means for turning the data into usable information is to transmit it by means of an open source communication protocol, such as Modbus or BACnet, and it should be Internet-based. This will make it possible to use software to display, analyze and communicate patterns of energy consumption.
Using data to connect to people
The Vornado Realty Trust, which owns and manages 28 office buildings in Midtown Manhattan, started implementing these ideas by installing a submetering system that is based on meters with pulse outputs. Vornado provides real-time energy usage information in 15-minute intervals to its tenants, using an open-source “energy information portal (EIP),” which was developed to capitalize on the 2,500 meters that are already installed. Within two weeks after installing the EIP—which allowed the tenants to monitor their usage day by day and throughout each day—the energy used by their tenants was cut by 15 percent, and that reduction was permanent. To emphasize the significance of that reduction, consider that tenant energy use accounts for 70 percent of a building’s overall energy profile in Vornado Realty Trust’s New York office portfolio, according to Sukanya Paciorek, vice president, corporate sustainability.
Using data to save energy
Two major ways to capitalize on usage feedback are to lower peak demand and pinpoint waste, e.g., unnecessary systems left on during weekends or periods of high demand. Lindsay Audin, president Energy Wiz Inc., presented ways of visualizing data to highlight patterns of use over time and for different users. These included 3-D graphics and data compatible with Excel.
What does this mean for electrical contractors? E-Mon Electric (recently acquired by Honeywell) has an answer: For the contractor, this becomes a win-win situation, as the contractor makes money installing the submeters that allow the rate payers to save money on their energy bills. And our environment benefits because, overall, less energy is consumed. This is something that an aware contractor can sell to customers, especially during upgrades.
“Most of the jobs I’ve handled recently come from a customer request and my making submetering a need,” said Dan August, Mona Electric, Clinton, Md. “We offer complete tech support after our installations and maintain contact. From this, I can tell you that client comments about submetering [after installation] have been very positive.”
For owners, installing submeters, networking them and setting up analysis software requires a one-time expenditure of dollars, but if these systems are used intelligently, the costs can be recouped in short order. This investment is far less than the cost of installing and running various control or alternative-energy systems.
For the environment, it means a rapid and significant drop in energy consumption. For contractors, it’s a significant source of business, both for the installation and ongoing service.
All these benefits can be achieved by adding people to the feedback loop.
BROWN is an electrical engineer, technical writer and editor. For many years, he designed high-power electronics systems for industry, research laboratories and government. Reach him at firstname.lastname@example.org or at www.writingengineer.com, an independent professional writing service.