Every house and building with electricity has at least one electric meter—the device that measures how much electricity is consumed (and in some cases, generated). Often one is enough, but there can be important advantages to having more.
In the summer of 2011 the Alliance undertook the latest in its series of upgrades related to the Alliance Center’s high-performance building renovation project: the installation of extensive submetering gear throughout the building. The effort is making it possible to monitor and record highly detailed data on electricity use hour by hour, floor by floor, and function by function throughout the year. Once baseline data have been acquired the same devices will be used to record the effects on energy consumption of various social and technical interventions to follow under the renovation project.
The Alliance Center’s submetering configuration is state of the art and enlarges the envelope—and the possibilities—of this data collection method. Typical commercial space is submetered by tenant, with a separate meter for the building’s data center. (Of course, mixed-use buildings often have meters for each unit.) Beyond that, deeper submetering is rare. Even among buildings certified under version 3 of the Leadership in Energy and Environmental Design (LEED) criteria—which itself is unusual—it’s uncommon for a building to earn any submetering credits, even though one point can be earned by submetering only 40 percent if the space (two points for 80-percent coverage). In contrast, the Alliance Center is now 100-percent submetered, creating an unprecedented fine-grained level of data resolution. Combined with a data logger and the right software, these data are enabling real-time and historical monitoring, comparison and display of extremely detailed and disaggregated energy end use.
The submetering project involved installation of 40 transducers and 164 current transformers (CTs), both devices that measure current and voltage in individual electrical lines. The transducers and CTs are distributed by floor and end-use so as to capture each floor’s consumption of energy for lighting, heating, cooling and plug loads (office machines, microwaves, etc.), as well as elevator energy use. The system also measures the disaggregated energy used by each component of the roof-top unit.
What’s the point of collecting all these data? The first principle of controlling the use of a resource is being aware of how much you’re using. Equipping a building this thoroughly with energy-metering hardware and data collection devices will radically raise the level of tenant awareness of energy consumption and offer insights into specific types of use that might benefit from conservation efforts. The data will also enable fine-tuning of our modeling of the building’s energy use, and thereby make it possible to experiment with particular technologies and determine their precise effects on consumption. Eventually it will even be possible to test innovative social arrangements, such as a within-the-building “cap-and-trade” system, in which a goal is set for maximum energy use, tenants are allotted a quota of energy “credits” and then can trade among themselves, with low-consumption tenants selling their excess credits to tenants who find it more difficult to cut back.
