Foursquare is principally funded by Union Square Ventures , Andreessen Horowitz , O'Reilly AlphaTech Ventures , and Spark Capital . The company raised $ million in its Series A round and $20 million in its Series B round .   On June 24, 2011, Foursquare raised $50 million on a $600 million valuation.  Their Series D round funding of $41 million was announced on April 11, 2013 and led by Silver Lake Partners .  Unlike prior funding rounds that had been financed via equity , a good portion of Series D came in the form of convertible debt from existing investors. 
Degree days are unfortunately rather easy to use badly (in a way that leads to erroneous and misleading figures), and rather difficult to use well. It can also be hard to turn degree-day-based analysis into actionable tasks that reduce consumption. There are better ways for beginners to get started saving energy (like, for example, obtaining and using a Kill-A-Watt meter to find electrical waste, and a cheap infrared laser thermometer to find thermal leaks). For these reasons, Degree is primarily aimed at the energy-saving professionals that are already experienced in using degree days as part of a broader energy-management strategy.