Frank McInnis, Emcor's US chief executive, said that Emcor UK would need to expand in order to carry out the extra work. He had therefore given it the green light to make acquisitions.
McInnis said: "We have the funds available and if the Emcor group is successful in the facilities management contracts we are pitching for, then we would look at expanding our capacity."
McInnis refused to be drawn on the names of the 15 companies that are being approached but two are understood to be Procter & Gamble, the American household products and pharmaceutical maker, and heavy equipment manufacturer Caterpillar.
All of the companies are already customers of Emcor's US parent.
McInnis said he was keen for Emcor UK and Emcor US to build on each other's relationships with existing customers.
For example, Emcor US could benefit from its British subsidiary's link with pharmaceuticals group GlaxoSmithKline.
Norman Critchlow, chief executive of Emcor UK, said the business in the US had been based on the successful UK model of a balance between construction and facilities management.
He said: "With large multinational companies, global FM is a major opportunity to link our US and UK companies."
He said that Emcor's turnover in the FM sector now exceeded that of its projects division. Turnover in facilities management is about £200m, whereas projects turnover is £175m.
McInnis added that the US arm of Emcor had also just appointed Mava Heffler as a vice-president of communications. She will be responsible for developing the Emcor brand along with Barbara James, her counterpart in the UK.
Heffler will be spending time in the UK during the transition period as Emcor breaks away from its previous branding as M&E specialist Drake & Scull.