The survey of 130 European and North American firms showed that 38% were using environmental criteria in their selection of IT equipment, up from 25% in April.
The research report said that although there was still a gap between awareness and action, this gap had narrowed in the past six months.
The report said many IT suppliers had indicated an increase in green considerations in purchasing decisions, especially in Europe.
Although only 15% said they had an overall plan for implementing green IT, 25% of respondents said they were in the process of creating a plan, and 39% said they were considering it.
The report said saving money on energy-related costs was the main reason for IT departments going green. Saving the environment was only the second most popular motivation.
Forrester said the survey results reinforced the research firm's long-held belief that economic and environmental motivations were closely aligned and working together to push companies towards green IT initiatives.