It might surprise you to know that a one-stop shop for energy services for buildings is one of the fastest growing private companies in Massachusetts. Yeah, really. The startup is called Next Step Living, founded in 2008, and they help customers find energy services like window replacement, new insulation, air sealing and figuring out the best options for a solar roof.

In fact the company is growing so quickly -- they have 800 employees and have worked with 75,000 homes -- that they announced on Wednesday that they've raised another round of $25 million in Series D funding. New investor Braemar Energy Ventures led the deal, which also included VantagePoint Capital Partners and the family office group Black Coral Capital.

Pumping new insulation in a home. image courtesy of ilovebutter, Flickr Creative Commons.

Pumping new insulation in a home. image courtesy of ilovebutter, Flickr Creative Commons.

Next Step Living raised their last round, a Series C of $18 million, back in December 2012. Investors in previous rounds also included Massachusetts Green Energy Fund, The Windquest Group and dozens of angel investors.

Energy efficiency services and home solar services go hand in hand. When home owners are looking to upgrade, often times they want to do multiple things. Also making a home more energy efficient, means more efficient use of the solar panels. SolarCity and other solar installers commonly also sell energy efficiency services.

Solar panels, Image courtesy of Jon Callas, Flickr Creative Commons

Solar panels, Image courtesy of Jon Callas, Flickr Creative Commons

Solar is has been seeing dramatic growth in the U.S. over the past couple of years. The U.S. installed 1.3 GW of solar in panels in the first quarter of 2014, which was growth of 79 percent from the first quarter of 2013. There's currently 13.4 GW of solar panels operating in the U.S., which is about 482,000 systems.

Currently Next Step Living only operates in Massachusetts and Connecticut, but it wants to use the funds to help expand to other states. The company says it's New England homeowners have achieved almost $18 million in energy savings, and they hope that will grow to more than $90 million in the next five years.