Ciarán Cuffe (Dún Laoghaire, Green Party)
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Question 617: To ask the Minister for the Environment, Heritage and Local Government his views on new research mentioned on a television programme in October 2006 (details supplied), which indicated that two houses which both meet the building regulations on energy efficiency but where one house, meeting the requirements as measured by the overall heat loss method, may in fact be up to 30% more energy efficient than another house which meets the requirements as measured by the elemental method; and if he will make a statement on the matter. [35374/06]

Ciarán Cuffe (Dún Laoghaire, Green Party)
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Question 618: To ask the Minister for the Environment, Heritage and Local Government the reason there are two measures of energy efficiency, elemental and overall heat loss, acceptable under the Building Regulations; if his Department has conducted or commissioned comparative analysis research of the two methods; if not, his views on commissioning such research; his further views on whether efficiency efforts might benefit from only one measure of energy efficiency being permitted under the regulations; and if he will make a statement on the matter. [35375/06]

Dick Roche (Wicklow, Fianna Fail)
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I propose to take Questions Nos. 617 and 618 together.

The May 2006 edition of Technical Guidance Document L includes two methods of demonstrating compliance with Part L (Conservation of Fuel and Energy) of the Building Regulations. The primary reason for allowing the two methods is to provide options for some flexibility in how heat loss through the building fabric is limited, via the Overall Heat Loss (OHL) method, and a simple method — the Elemental method suits those who do not wish to deal with the complexity of additional calculations.

Part L standards for Dwellings are due for revision in 2008 at the latest, as required under the EU Energy Performance of Buildings Directive. In this context, the appropriateness of continuing the two methods will be considered.

The Question appears to refer to a report (30 May 2006) by the UK based Building Research Establishment (BRE), which was commissioned by an Irish timber frame manufacturer. The report sets out a calculated comparison of the above two methods of achieving compliance with Part L for a small sample of English dwellings.

In its conclusion, the BRE report claims that houses built to comply with the elemental method (and not the OHL method as cited in the Question) will use about 30% less energy for space heating than the those complying with the OHL method.

This conclusion is not necessarily accepted by my Department as the BRE Report does not contain sufficient information to allow independent review and validation of its assumptions and calculations.