ALMOST three-quarters of all new homes in this area are built on sites previously used for industry, says a survey.
Britain's general union, the GMB, says councils should do more to make sure more homes are built, so workers can be nearer their jobs.
The figures come from a new study covering 2002/2003, compiled from information supplied by planning departments to the Audit Commission.
They show that 70% of homes in Kirklees are built on such sites - known as brownfield areas - and 74% in Calderdale.
Sheffield was the highest, with 92% of new homes.
East Yorkshire was the lowest, on 18%.
A GMB spokeswoman said: "These figures demonstrate that there are large variations in the percentage of housing that council planning departments are able to secure on brownfield sites.
"There is an urgent need for more homes to be built for key workers in built-up areas, so they can be reasonably near their jobs.
"Environmental considerations and the needs of workers for affordable housing can be combined, provided public policy on social housing is focused and applied.
"The GMB want to see councils themselves building this social housing, like they used to do."