UPDATED October 16, 2016, 12:44 a.m.

Winter is coming—but that does not mean the same thing for every room in Eliot House.

Opened in 1931, Eliot is heated by a steam-driven heat exchanger that transports hot water throughout the building when temperatures fall below 48 degrees. Aldis Elfarsdottir ’19, an Environmental Science and Engineering concentrator, noticed that this system gives students little control over the temperatures in their rooms and has begun to devise a way to mitigate the problem.

After Elfarsdottir noticed people across campus leaving their windows cracked open in the middle of winter last year, she began working with the Harvard Office for Sustainability to determine the amount of energy that was wasted and its environmental implications.

Elfasdottir worked with Christopher P. Bitzas, a Siemens energy engineer, and found that Eliot House lost 358 million British Thermal Units (BTU) of thermal energy last winter due to leaving windows open—more energy than the average American uses per year.

From there, Elfarsdottir attended a workshop at the School of Engineering and Applied Sciences to think of solutions, where she met Patrick K. Kuiper and Patrick B. Day, who received master’s degrees from SEAS in May.

Realizing the need for concrete data on temperature and humidity, the team installed Edison development boards in 15 dorm rooms in Eliot.

Rooms closer to the generator are often overheated, while those farther away can be drafty and cold, according to Elfarsdottir. The end result is an inadequate and inefficient heating system, which leaves Eliot with climate zones that range from tundra to temperate to tropical.

Elfarsdottir plans to develop an intricate map of Eliot’s rooms based on temperature with this data. She said she hopes that students will use this map in future years to select rooms based on their heating preferences, which in turn will lead to less energy waste.

“This is a good example of seeing the way that we interact with our environment and being conscious of the fact that our day to day actions have environmental implications” Elfarsdottir said.

Elfarsdottir, Kuiper, and Day found that the cost of the wasted energy has not only environmental implications but financial ones too. Closing all the windows in Eliot would save the House about $9,900 and the University $4,200 each year, according to the project’s final report.

“Some of the key benefits are one that it can really increase the occupant comfort of students in their rooms and it could also at the same time lower energy costs, and therefore greenhouse gas emissions as well,” Heather A. Henriksen, the Director of the Office for Sustainability, said.

This article has been revised to reflect the following correction:

CORRECTION: OCTOBER 16, 2016

A previous version of this article incorrectly attributed a quote to Naomi G. Asimow.