Key workers and young families in rural areas will benefit from changes to the planning system announced on Monday.

However, opportunities to build thousands more affordable homes could already have been missed because of delays in introducing the changes.

Updates to the Planning Policy Guidance Note 3, published with the ODPM’s five-year plan, state that planning applications for housing or mixed-use developments targeting redundant commercial land should be considered favourably.

The updates also say that local planning authorities could allocate small sites solely for affordable housing in small rural communities. The homes would have to be permanently dedicated to meeting the needs of key workers and local people.

But consultation on plans to reduce the lowest threshold above which affordable housing can be sought from 25 to 15 units and 1 to 0.5 ha is continuing two years after views were first sought.

Responses to the initial round of consultation on those plans were received in 2003.

The plans are still included in the document but will be consulted on for a further 12 weeks before they are launched in the summer.

The document concluded that had the new threshold been introduced from 2002, “approximately 12,000” more affordable homes would have been built in each year since.

Robin Tetlow, director of consultant Tetlow King Planning, welcomed the updates to PPG3 announced this week but said that lengthening consultation on lowering the thresholds would have a negative impact.

He said: “I think opportunities are being lost to deliver affordable housing. They still haven’t been able to confirm the thresholds.”