Technology;|;DOI: 10.1145/1743546.1743554
Tom;Geller
Beyond the smart Grid
Sensor networks monitor residential and institutional devices,
motivating energy conservation.

As PresiDenT-eLeCT, BArACK Obama used the term “smart grid” in his first major speech of 2009, and few phrases have enjoyed as much currency recently. The electrical grid isn’t the only utility acquiring intelligence, however, as water and gas meters throughout the U.S. gain radio communication capabilities and other innovations.

But those grids (and their attendant smartness) stop at the residential meter, so consumers never know which household devices are the biggest energy users. Once monitored, these devices would need to communicate—to turn on the ceiling fan and adjust the air conditioner when electricity prices peak, for example. The final ingredient for such a system to be useful to consumers is an easy-to-understand interface for monitoring and controlling the devices.

The solution, like the problem, has three parts. First, monitor each device separately; second, network them together for coordination; third, present the resulting data in an easy-to-use format. As it happens, this solution goes beyond energy conservation to suggest new ways of integrating home automation, safety, security, and entertainment applications with smart grid data.

wireless transmitter
toilet 1

bathroom sink 1

bathtub
water
spigot
kitchen sink
dishwasher
sensor
thermal
expansion
tank
incoming cold
water from
supply line
water
meter
pressure
regulator
backflow
preventer
hot water heater
drain valve
bath
sink 2

hot water
heater
washing
machine
shower
toilet 2

hydrosense can be installed at any accessible location in a home’s water infrastructure, with typical installations at an exterior hose bib, a utility sink spigot, or a water heater drain valve. By continuously sensing water pressure at a single installation point, hydrosense can identify individual fixtures where water is being used and estimate their water usage.

Your home’s five senses

The first key part is the sensors themselves. For utility monitoring, installation has been a major barrier to consumer adoption. Measuring water flow to a specific faucet, for example, required removing a section of pipe. To give a residential consumer the whole picture, this process would have to be repeated for every faucet in the house.

But now work done by Shwetak Pa-
tel, an assistant professor in the de-
partment of computer science and en-
gineering at University of Washington,
and colleagues can extrapolate electri-
cal, water, and gas use of individual de-
vices by measuring the “shock waves”
created when consumers turn on the
devices that use those utilities.