Laing, Tarmac and Railtrack revealed plans to improve their environmental performance. And a Major Contractors Group survey of 15 of its 23 members found that they were taking their green responsibilities seriously.
Despite these efforts, Construction Confederation chairman Alan Crane told the conference that the construction industry needed to do more: "Lots of the things we do have a negative impact and cause temporary and permanent damage, and it is this side of the industry that we have to address.
"There is an agenda that will not go away. We can deal with it as a threat, as we deal with most things in this industry, but we'll do better if we look at it as an opportunity."
The measures announced by Laing chairman Sir Martin Laing include changes to the firm's annual report, which this year for the first time will include an audit of its social, environmental and economic contribution to green causes.
In future, targets for the number of homes built on brownfield sites, contributions to local training and handling of materials and waste are likely to be checked by an external auditor.
Laing director Christopher Laing, who is heading the initiative, said Laing would do an environmental audit of its buildings. Leases will not be renewed where space and energy is not maximised, he said.
Tarmac, once notorious for building through beauty spot Twyford Down, is now taking some of the most radical steps to improve its green performance. It has agreed to subject its quarrying division to a Natural Step audit, a rigorous environmental assessment programme imported from the Continent.
Its environmental adviser, George Martin, said the firm's green taskforces and committees had drawn up a range of best-practice measures to be applied across Tarmac sites.
Railtrack development director Martin Reynolds, who is in charge of a £1bn station regeneration programme, called for less talk and more action on green issues.
He said the client was studying whole-life costing as a better form of procurement and may adopt "sustainability indicators" to assess bids from suppliers.
Railtrack also believes that, by having designers working directly for contractors, environmental issues will be addressed more clearly, preventing confusion on what it wants from its suppliers.
The MCG survey, carried out by Environmental Governance in February, showed that the 15 firms surveyed had a main board director with responsibility for the environment.
The firms all publish, or plan to publish, an environmental statement. Nearly 90% have specific environmental policy objectives and 70% are implementing annual green targets.