75F is one fairly hot small business based in often-chilly Minnesota.

Founder Deepinder Singh, a software engineer by training, started brainstorming 75F a decade ago after he was frustrated with his efforts to control the temperature in the baby's room of his drafty Mankato house.

He now runs a Burnsville company that has 50 employees, has raised several million dollars from investors and expects to exceed $3 million in revenue this year.

75F, in its third year of commercial operations, is not what he envisioned when he won the Minnesota Cup and National Clean Tech Open in 2014.

"I had a vision of every office or room with temperature controls," Singh said. "And we have third-party studies that we save energy, up to 70 percent of heating costs and, we think, 30 to 50 percent of cooling costs.

"But we've gone from just saving energy for owners to making people more comfortable and the indoor air quality [better]. We want people to be healthy, comfortable and productive. And healthy buildings, with no mold, etc."

Singh, who once worked on network systems for large telecom providers, including AT&T and Verizon, won an "eco-imagination" award from General Electric in 2011 for his fledgling software.

He continues to focus on small commercial buildings and retail and restaurant chains to avoid huge competitors like Honeywell and Johnson Controls.

The evolution of the internet, cloud computing and low-cost sensors have enabled 75F to develop an "internet of things" approach that senses and reacts to the weather, the indoor environment, people in a room, time of day and other factors to control air quality, temperature, lighting and ventilation.

"The 'Legos' were all out there," he said. "We try to be the Lego master.

"It's the democratization of technology. Normally you would need a mechanical engineer and training by Johnson Controls. We've made it so simple that kids could install [a 75F system] using a five-minute video."

In fact, 75F's website features a video of some kids from a nearby Burnsville elementary school installing one.

75F claims dozens of customers at hundreds of sites.

They range from a small commercial building at 300 N. 1st Av. in the North Loop, to Border Foods, a Minnesota-based franchisee of fast food restaurants, to TurnKey Corrections in River Falls, Wis., a manufacturer of vending machines, to office towers in Bangalore, India.

"We started installing 75F systems about two years ago," said Brian Davies, facilities manager for Border Foods, a franchisee of 187 Taco Bell restaurants. "Every restaurant as we build or remodeled. We had an issue keeping employees comfortable in the kitchen near a hot-food line. 75F saves on utilities, reduces wear and tear on equipment, and establishes better airflow. But our initial primary concern was employee comfort. It worked."

Davies said the payback period per installation is about 2.5 years in his energy-intensive business.

"Additionally, we found that … with an installed 75F system, we could downsize our HVAC systems as we installed new ones. It was a savings of $2,500 to $5,000 on a new install through a smaller system. And I have an app on my iPhone and iPad, so I can see, in case there is any issue, how any unit is operating for the last 24 hours. I can troubleshoot an issue from my living room chair."

Singh, courteous and soft-spoken, said 75F has had success in the large-building market in India because his system is simpler, cheaper and easier to manage than those of some larger U.S. competitors.

Jay Schrankler, the veteran Honeywell engineer who once ran its heating and cooling controls business, was one of 75F's first individual investors in 2014. Schrankler now runs the University of Minnesota technology commercialization office.

Schrankler was impressed that Singh self-funded development of 75F and did a lot of the work himself.

The growth of 75F also demonstrates that building owners still care about energy costs and indoor environment, even in the third year of lower natural gas costs. The systems, which cost several thousand dollars per site, typically pay for themselves within a few years.

Singh, raised in India and schooled in Canada, considers himself a social democrat who has distributed stock options to every employee, some of whom have left higher-paying posts to join him at 75F.

"This is not a cooperative," Singh said. "I am the single largest shareholder, but I want people here to be vested and have a stake.

"I've been part of six start-ups over the years," said Singh, 42, also once a marksman on the Canadian national shooting team. "And this is the best bunch I have ever been with. If this company doesn't succeed, I think it will be a real shame."

Singh and his wife, a physician, live with their two children in a house where there are no longer temperature-control problems.

"I'm proud that my kids say their dad works for 75F," he said.

Neal St. Anthony can be contacted at nstanthony@startribune.com.