Begbies Traynor is now running the Cornish based company.
Enact has been in business since 1996 and has worked with more than 100 local authorities to upgrade 300,000 properties.
The firm became the first in Cornwall to achieve Green Deal Provider status from the Department of Energy and Climate Change in January.
It was one of the 22 Green Deal pioneers alongside Carillion and Willmott Dixon.
Enact also signed a recent deal with the Residential Landlords Association to provide Green Deal upgrade work.
The company had set a target of upgrading 10,000 properties over the next five years valuing the contract at £100m.
Christopher Norman and Ian Walker of Begbies Traynor business restructuring and insolvency advisors have been appointed as joint administrators.
Norman told This is Cornwall: “29 members of the company’s staff were made redundant on the appointment of the joint administrators on account of the company’s insolvency.
“The company has retained some of its employees to assist the administrators in conducting an orderly winding down of the company’s affairs.
“We will now attempt to source a purchaser for some or all of the company’s business undertaking and assets.”