Tarmac Building Products has launched a new guide to thermal insulation for housebuilders and designers, outlining the recent legislative updates to Part L of the Building Regulations.

The 31-page guide, which is part of a wider piece on Tarmac Building Products’ range of concrete blocks, breaks down the changes to the regulations that came into force on 6 April 2014. It covers the requirements for new buildings and alterations to existing buildings, while providing case studies that focus on practical solutions for typical housing types.

The guide also outlines some of the entirely new metrics used to measure thermal efficiency, such as the ‘Target Fabric Energy Efficiency’, which has been introduced alongside the pre-existing Target Emission Rate (TER) and the Dwelling Emission Rate (DER), to limit demand for space heating and cooling.

Under the changes, a new dwelling’s DER must still be equal to – or less than – the TER, which has been broadly reduced by 6% and 9% for housing and other buildings respectively, compared to the 2010 Part L CO2 emissions.

Ian Gray at Tarmac Building Products said: “The changes to Part L affect people at all levels across the construction industry, from local builders right the way through to national housebuilders, as well as architects and designers.

“As these changes are mandatory, we want to ensure everyone has access to the right information, which can enable them to review their construction practices. We hope this guide will dispel any confusion, especially during the initial transition period, for those who have new sites impacted by these changes.”

As well as explaining the updates, the document includes case studies on domestic properties, which illustrate a range of measures that could achieve a cost-effective solution to the challenges set by the updates to Part L. In particular, the guide shows how improved glazing, wastewater heat recovery, or renewable technology can be used to modify the basic specification.

A set of U-values tables for cavity walls and ground floors are also included to provide a good starting point for defining a suitable specification.

Tarmac Building Products’ Thermal Insulation guide is available to download from its website.