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Technical Guidance Document Part L 2019 will be effective after 1-November-2019


The new TDG Part L 2019 for “Conservation of Fuel and Energy – Dwellings” will come into effect after 1-November-2019.

To comply with this new building regulation for all domestic houses, we will need to achieve as a minimum the following standards in energy conservation:

  • Roof U-value of 0.16 W/m2K
  • Wall U-value of 0.18 W/m2K
  • Floor U-value of 0.18 W/m2K
  • Windows and doors U-value of 1.4 W/m2K

Similar to TGD-L Other Buildings 2017, section 1.2 of TGD-L Dwellings 2019, requires that a RER (Renewable Energy Ratio) based on an assessment of the MPEPC (Maximum Permitted Energy Performance Coefficient) and an assessment of the MPCPC (Maximum Permitted Carbon Performance Coefficient) be calculated.  This calculation procedure differs from TGD-L Other Buildings 2017, as it uses DEAP (Dwelling Energy Assessment Procedure) which 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.  A RER of 0.2 represents 20% of the primary energy from renewable energy technologies to total primary energy as defined and calculated in DEAP.

The primary difference in Sections 1.2 between TGD-L Dwellings 2011 and TGD-L Dwellings 2019, is that in TGD-L 2011, the home owner was only required to produce 10 kWh/m2/annum thermal energy (or 4 kWh/m2/annum electrical energy) from renewable technology sources, whereas in the new TGD-L 2019, the home owner is now required to produce 20% of the primary energy from renewable energy technologies.

Section 1.3.4 of TGD-L Dwellings 2019, deals with building envelope air permeability requirements, including air pressure testing, limiting the effects of solar gain, and limiting the effects of overheating.

More information on this revised Technical Guidance Document is available on the Department of Housing, Planning and Local Government website at this address:  https://www.housing.gov.ie/housing/building-standards/tgd-part-l-conservation-fuel-and-energy/technical-guidance-document-l-2