What to do when you're freezing in NYC—indoors

In New York City, it can be hard for some people to keep the heat on inside their own apartments. But a start-up is trying to help apartment dwellers fix the problem.

Every year, authorities in New York City receive more than 200,000 heating-related complaints. Building managers are required by law to maintain minimum temperatures of 68 degrees during the day and 55 degrees at night, but it doesn't always happen. Many apartment tenants are left shivering in their homes anyway.

Getting anything done about the problem can be an excruciating process for tenants. Battling a landlord in court requires tenants to keep "heat logs" that record the temperature inside and outside their apartments every hour.

Heat Seek, a non-profit start-up, is looking to help tenants fight back. Heat Seek is designed to help tenants by giving them web-enabled sensors that track temperatures and automatically record when an apartment is in violation of heating laws.

Read MoreThe world's best — and worst — housing markets

The company, which was sparked by a project from classmates at Flatiron School, a New York-based college for computer programmers, won a coding competition called BigApps Battleground and rose more than $15,000 on Kickstarter.

For Harlem resident Rebecca Sharp, who said she has spent the last two years battling her landlord in court over heat and other basic services, Heat Seek couldn't come soon enough.

"It's like the answer to a prayer, really, because it's almost impossible to get a violation for heat," she said. "People just give up, because it can seem like you're at the bottom of a huge mountain of stuff that has to be done."

An email from CNBC to attorneys for Sharp's landlord went unanswered.

A man holds an electric heater in his freezing apartment in the Rockaways after losing heat following Hurricane Sandy on January 25, 2013 in New York City.
Getty Images
A man holds an electric heater in his freezing apartment in the Rockaways after losing heat following Hurricane Sandy on January 25, 2013 in New York City.

In the first week the sensors were installed in her building, the tool recorded data indicating multiple heating violations.

But as much as the tool could mean to tenants, Heat Seek maintains that its product can be just as useful for the other side.

Read MoreHome builders' new sweet spot: the 55-plus crowd

"For building owners, it can also be a cost-savings tool," said Heat Seek's community outreach director, Noelle Francois. "Or maybe you need to engage in some weatherization so that the building is staying more evenly heated."

Brooklyn Borough President Eric Adams announced a partnership this year that will bring the sensors to 10 buildings in that borough.

"[It's] an incredible technology that allows good landlords to see where they're losing heat," he said.