Dr. Ciaran Byrne:

There was a reduction in grant amounts. Rather than just flat-fee grants for attic and cavity wall insulation, the grants were ascribed to different house types. A detached, four-walled house got a slightly larger grant than a semi-detached or terraced house etc. The nature of those changes, combined with the fact that between 2009 and 2011, a significant amount of pent-up demand was satisfied, resulted in a drop-off in the scheme.