Optimum Energy, which makes software to manage heating and air conditioning systems at airports, universities, data centers and other buildings, has received a commitment for $4 million from its existing investors. The Seattle upstart has brought in $1.2 million of the new round, with the remainder of the capital available to the company as it grows, said spokeswoman Heather Van Schoiack.

She said that the money will be used to support strategic initiatives, including the expansion of channel partnerships. Total funding in the 44-person company -- led by Nathan Rothman -- now stands at just under $15 million.

Optimum says that its software can reduce the energy used to heat and cool buildings by 30 to 60 percent. Customers include the San Jose International Airport, Randall Lamb and The University of La Verne.

The University of Texas at Austin also has implemented the Optimum software at one of its chilling plants. In the first year of operation, the system was expected to reduce energy consumption by six million kWh and save the university $500,000.