University of Virginia associate professor Kamin Whitehouse thinks people want to know where everyone is in their house: Who’s taking the long shower? Who left the air conditioner on when they left the house? “Today’s smart home sensors are about appliances, lights, and devices in the home, but not really about the people,” said Whitehouse. “By demonstrating the exciting things that become possible when a home better understands the people who live there, we hope to inspire a new generation of products and technologies.”

Marauder’s Map in Harry Potter and the Prisoner of Azkaban

To make his point, Whitehouse outfitted four Charlottesvile, Virginia, homes with sensors to track who enters what room, and what appliances and utilities that person uses. The data is then beamed up to the cloud and back down to a smartphone app named the “Marauder’s Map.” Harry Potter fans will recognize the reference to “The Prisoner of Azkaban,” in which Harry uses a magic map to track the footsteps of characters and unlock the mysteries of his school. Whitehouse has been similarly tracking the people in these four homes and, by mid-September, will complete a four-year study of their activities.

Smart sensors in the home are not new–Google, Apple, and Staples all have footholds in the smart home marketplace. While many companies’ sensors require people inside the home to wear tracking devices, log in their activities and/or use intrusive cameras, Whitehouse’s map collects data entirely via custom sensors. The doorway sensors called ultrasonic range finders determine who enters a room by measuring their height. Anywhere from 30 to a few hundred more sensors throughout the home and on the water and power mains then track what the people in the homes are doing.

“We are understanding the data without making the occupants use wearable tags and cameras,” said Whitehouse. “We’re the only system doing that.”

But just as one could avoid detection from Harry’s map by entering into the Room of Requirement, Whitehouse’s prototypes are not fool-proof. Juhi Ranjan and Erin Griffiths, graduate students at UVa, said the doorway sensors had to be plugged in–occasionally people were unplugging them and forgetting to reconnect them. (Battery-powered prototypes are still in the works.)

The goal of the Map app and of Whitehouse’s research is to allow people to see what’s happening in their home and then make smarter decisions about energy consumption. Though there are inevitably other disruptive possibilities–just as an iPhone makes for a pretty good camera, a house that tracks everyone’s coming and going makes for a pretty good alarm system. Installing smart sensors which can tell if a non-occupant has entered the home and alert the homeowners “save people a lot of money” for people who are currently buying home security, said Whitehouse.

Action: Using the kitchen sink

The ability to track the movement and actions of people in your home also has obvious applications for dependents and caregivers. Did Grandpa leave the stove on after cooking and then retire to the front porch? Maybe someone should call and tell him.