He may have angered gamblers and Mancunians this week by scrapping his predecessors' Super Casino project, but prime minister Gordon Brown received tentative praise from environmentalists after all of the government's planned green reforms emerged unscathed as part of his first legislative programme.

Addressing parliament on Wednesday offered few surprises as he confirmed that the proposed Climate Change Bill, which will set legal targets for a dramatic reduction in carbon emissions by 2050, will form one of the centre pieces of the government's legislative agenda this autumn. However, he disappointed environmental campaigners who have been calling for annual targets by maintaining that the new bill would set five year emission reduction targets.

The new Climate Change Bill will be supported by reforms to the energy and transport sectors with the new Energy Bill providing "greater incentives for renewable energy generation", while the Local Transport Bill will "support the Government's strategy to tackle congestion and improve public transport".

Brown was also at pains to emphasise the green credentials of his headline grabbing commitment to build 3m new homes by 2020 as part of the largest building programme seen in the UK since the fifties.

Under the proposals, the government has pledged to focus the new building on brown field sites and estimates up to 160,000 new homes could be built on sites currently owned by central government. Brown added that this focus on brown field sites would allow the government to "continue to protect robustly the land designated as green belt".

Brown also pledged to use the New Towns Act to consult with local councils and accelerate the building "eco towns" consisting of zero or low carbon housing that are built using so-called "passiv haus" principles to slash building's energy requirements.

The proposals were also broadly welcomed by the Local Government Association (LGA), but it also warned that the plans would have to be properly resourced if they are to prove successful.

"We support the idea of eco towns, but the issue has always been getting the funding for the infrastructure that has to go with such housing," said an LGA spokesman. "Equally, it is good to hear the government talking about using brown field sites, but there is not a shortage of space for new builds at the moment, the problem is the money for the accompanying infrastructure."

He added that the government should also tighten the environmental standards imposed upon private developers. "At the moment private developers don’t have to meet the same green standards as councils and local housing associations," he complained. "We need to make sure all houses are built to the highest standards."

However, a spokeswoman for the Department for Communities and Local Government insisted the government was moving to improve building standards across the board, arguing that all the proposed new builds would be subject to tightening regulations governing the environmental impact of new buildings under the recently unveiled Code for Sustainable Homes. "We want all new homes to be zero carbon by 2016 and there are staging posts along the way to that whereby new builds will have to be 25 percent more energy efficient than current regulations demand by 2010 and 44 percent more efficient by 2013."

Construction industry body the Green Building Council said that the private sector was reacting positively to the new standards with these targets and insisted construction firms were prepared to meet the challenge of developing greener homes. "What the Code has given us for the first time is visibility over what is coming so firms can see where they need to invest to ensure they have the right skills to meet the new standards," he said. "It is a challenge but it is one the industry is taking up and encouragingly what we are seeing from some of the larger firms is that they are already pushing to meet the new standards ahead of schedule."

However, a spokesman for Friends of the Earth said that while the government's plans were welcome they were not ambitious enough. "We are very concerned by the timeline of having all new homes as zero carbon by 2016 - it is almost ten years away and we know it is possible to build zero carbon homes now," he said.

Environmentalists will also point out that tighter building standards will only prove effective if they are stringently enforced. A recent edition of the Dispatches programme on Channel 4 revealed that there had not been a single prosecution for builders who failed to meet energy efficiency standards since they were introduced in 1985, while a recent study by the Building Research Establishment found that 43 percent of new houses passed by inspectors did not meet current energy standards.

The Department for Communities and Local Government, however, insisted that ministers were aware of the issue and hinted that it was looking at ways of beefing up enforcement of green building regulations.