Anthony Erbetta formed the company in 1946 under the name of Boston Air Legasse Company, as a contractor, replacing and servicing heating ventilation and air conditioning systems. The name BALCO, an acronym of the incorporated name adopted shortly after its founding.

As BALCO grew, it also expanded beyond heating, ventilation and air conditioning contracting to include building operations and maintenance of mechanical systems.

At the request of the Bank of Boston (100 Federal Street), BALCO staffed the building with engineers to maintain the bank's new facility, hence the start of BALCO Maintenance, which is currently known as Building Technology Engineers, Inc.

ESII formed in 1984 as the holding company for its two operating divisions, BALCO and Building Technology Engineers, Inc. ("BTE"). BALCO's operations consisted of engineering, construction and service of environmental systems while BTE focused on building maintenance operations.

BALCO's services expanded into the Washington D.C. area under the name BTE Service, Inc., formed as a subsidiary of ESII. Because the name BALCO was relatively unknown in the Washington D.C. area, the BTE name was used to capitalize on BTE's established presence. In 2000, EMCOR Group purchased BTE.

We continue to use the BTE name today as it continues to be recognized as a leading service provider throughout New England.