Lifecycle environmental and economic performance of nearly zero energy buildings (NZEB) in Ireland

Directives in the European Union are ensuring that buildings in this region are moving towards nearly zero energy buildings (NZEB). For countries like Ireland, which has a temperate oceanic climate, a key to achieving NZEB is to have high thermal and air tightness performances of the building envelope. Consequently, as the operational energy of the building reduces, the embodied energy (and embodied global warming potential) typically increases as a proportion of the lifecycle energy of the building due to increased embodied energy of the building envelope and the lower operational energy. In order to assess if a design strategy is in fact sustainable, it is becoming essential to evaluate environmental and economic LCA of building design strategies. This paper presents the outcomes of a number of case study buildings in Ireland, which focuses on the full environmental and economic lifecycle assessment of buildings to assess the impact changes in building regulations are having on the contribution of both the construction and operation of a building's lifecycle as they move towards NZEB standards. If designed with a focus on achieving a high thermal and air tightness, a building with an embodied energy intensity less than a building that achieves compliance with 2011 Irish building energy performance regulations can achieve a NZEB standard.