Environmental Systems, Inc. (ESI) is a premier mechanical contractor & engineering firm headquartered in Attleboro, Massachusetts, with offices in Nashua, New Hampshire, and Warwick, Rhode Island. ESI offers full mechanical services from pre-construction through service and maintenance on all types of HVAC systems throughout New England. In our 45 years in the industry, we have completed design and installation of HVAC systems for more than 10,000 commercial projects, more than 2.5 million square feet of laboratories and clean rooms, and more than 70 MRI facilities, plus projects for many of the colleges and universities in our region.