The residential building market in Ireland has seen unprecedented levels of construction over the last ten years. Since 1994 the number of dwellings constructed each year in Ireland has increased by over 300%, with a record number of 80,957 dwellings constructed in 2005 [DOEHLG 2006]. With such a buoyant building construction market it is not surprising that in 2004 the residential sector accounted for 25% of Ireland’s total energy consumption [SEI 2005] and over half of this energy was due to the considerable level of space heating required in the maritime climate.
The significance of these figures is highlighted by the fact that Ireland’s greenhouse gas emissions were 23.5% greater than 1990 levels in 2004 despite a Kyoto Protocol target of +13% between 2008-2012 [EPA 2006]. With the EU Energy Performance of Buildings Directive (EPBD) due for implementation between 2006 and 2009 the awareness of building energy performance will increase substantially. Given these issues an ideal opportunity exists for the Passive House concept to be accepted into the construction of Irish dwellings.
Mandatory building regulations concerning the conservation of fuel and energy in dwellings, Technical Guidance Document - Part L (TGD Part L) were first introduced to Ireland in 1991, were amended in 1997 and again in 2002. The TGD Part L focuses on reducing energy consumption primarily by reducing required U-values, increasing insulation levels and minimizing thermal bridging. However, with two passive houses constructed in Ireland since 2002, the gap in standards between TGD Part L and the Passive House standard has been highlighted. Not only are Passive House minimum U-values for ground floor, wall, roof and windows significantly less than TGD Part L, as seen in Figure 2, but Passive House standards go much further by setting requirements for air tightness, passive solar gains and heat recovery whereas Irish regulations do not. The term Passive House refers to a specific construction standard for residential buildings with good comfort conditions during winter and summer, without traditional heating systems and without active cooling. A passive house has a high level of insulation with minimal thermal bridges, low infiltration and utilises passive solar gains and heat recovery to accomplish these characteristics. Consequently renewable energy sources can be used to meet the resulting energy demand.
• The total energy demand for space heating and cooling is limited to 15 kWh/m² treated floor area; and
• The total primary energy use for all appliances, domestic hot water and space heating and cooling is limited to 120 kWh/m².
In light of the awaited proposed amendment to TGD Part L and development of a calculation procedure for energy rating for Irish dwellings to comply with the EPBD, the UCD Energy Research Group undertook a study investigating the potential reduction for space heating energy and CO2 emissions when the Passive House space heating standard of 15kWh/m2 is applied to the Irish new build residential construction market
The tool used in this study was a computer-based model, developed as part of the “Homes of the 21st Century“ study [Brophy et al. 1999], which profiled the existing national dwelling stock by dwelling form, insulation characteristics and heating system types. The model was used to predict the energy consumption and CO2 emissions of dwellings with a typical floor area of 100m2, constructed to 2002 building regulation standard. This provided national common practice energy consumption and CO2 emissions figures for electricity, gas, oil and solid fuel (such as coal and peat).
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