Carillion Breathe Limited (CBL) aims to reduce the energy consumption and carbon footprint of public and private commercial buildings.
CBL will build on Carillion work as a Green Deal provider, offering design and build renewal projects for schools, universities, hospitals and other public sector buildings as well as industrial and commercial facilities in the private sector.
The nationwide business is headquartered in London and is already managing projects in Birmingham, Manchester and other parts of the UK.
Its managing directors are Sean Fitzpatrick and Gary Park.
Mr Park said: "We are very excited to form this new venture and deliver significant energy savings projects plus the associated financing to Carillion’s current and future customers, this will allow us to combine Breathe’s energy saving expertise with Carillion’s construction and maintenance experience to offer a compelling new service to our customers."