Building Regulations - Part L

The requirements regarding the conservation of fuel and energy in dwellings are laid out in the Technical Guidance Document Part L (TGDL) of the Building Regulations. The ultimate goal of Part L is to achieve carbon neutral dwellings in the near future. The requirements to achieve Part L compliance have changed dramatically over the last number of years and the current Part L 2011 represents a 60% improvement in energy efficiency in comparison to Part L 2005.

The Dwelling Energy Assessment Procedure (DEAP) is the official Irish methodology for calculating the energy performance and associated carbon dioxide emissions for the provision of space heating, ventilation, water heating and lighting in dwellings. DEAP is also the compliance tool specified in Part L of the Irish Building Regulations. DEAP performs compliance checking calculations for Part L and generates a conformance report summarising the relevant information for the purposes of building control.

The calculation checks that the primary energy consumption associated with the operation of the dwelling and the related CO2 emissions do not exceed the Maximum Permitted Energy Performance Coefficient (MPEPC) and the Maximum Permitted Carbon Performance Coefficient (MPCPC) when compared to a reference dwelling defined in the Building Regulations Part L Technical Guidance Document (TGD L). DEAP also checks minimum individual performance levels for fabric insulation, air permeability, heating system and controls and use of renewable energy.

It is essential that new dwelling designs, including heating and ventilation systems, are tested in DEAP at the earliest possible stage. This will give the greatest flexibility and choice to the Designer/Homeowner. DEAP can be used throughout the build process to check various options and combinations of systems and facilitate finding the most desirable and cost effective ways to achieve good energy efficiency and Building Regulation compliance. It is also important to note that meeting individual targets like back-stop u-values will not ensure compliance in relation to the whole dwelling performance as measured by MPEPC and associate MPCPC. TGDL 2011 does not specify how targets are to be reached and designers and builders are given discretion in choosing their own approach to achieving the required standard.

Reference: Technical Guidance Document Part L 2011