LIFE CYCLE ASSESSMENT &
LIFE CYCLE COST
The majority of buildings energy use has been associated with its operational phase with the main focus on reducing this energy use by key stakeholders. However, in order to achieve these operational energy reduction goals more materials are being invested into buildings. With the operational phase of a building beginning to have less of an impact over the lifecycle of a building, the impact of the energy associated with the building materials is becoming more prominent. Therefore, assessment of potential retrofitting plans must ensure lifecycle assessment (LCA) properties are coherently analysed to remove the possibility of creating an environmentally degrading lifecycle impact. Few robust studies exist and further research into the effects of potential retrofitting plans is necessary for an Irish context.
LCA analysis should incorporate at minimum an examination of embodied energy and global warming (GWP) emissions of installed building materials in addition to assessing the operational energy and GWP emission benefits. Thus, the influence of the building structural elements on building occupants, in particular related to their health and comfort, needs further investigation. Following comprehensive analysis, a more holistic environmental and economic impact of widespread retrofitting schemes can be truly quantified. One of the aims of the nZEB-Retrofit project is to methodically assess Irish buildings from a lifecycle energy consumption and GWP emissions perspective using EN standards.
The Life Cycle stages of a building according to EN-15978: 2011
The first part of the research examined 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 with the results published in an Energy and Building journal article (Insert Hyperlink). This paper presents environmental and economic lifecycle assessments (LCA) of typical new build two-storey semi-detached residential buildings in Ireland, using primary energy usage, global warming potential and economic costs as indicators.
The emergence of embodied energy (EE) and embodied GWP (EC) as a dominant construction environmental component is vividly noticeable as buildings move towards NZEB standard. For case study 1 (designed to 2005 energy performance standards), the EE and EC contributes 11% and 19% of the building’s environmental life cycle impact (Figure 1(a) and Figure 1(b)). For the two NZEB case studies (4a and 4b), the EE contribution increases to 33% and 31%, with the EC contribution increasing to 52% and 44% respectively. The results highlight the importance of a designer’s role in sustainably selecting appropriate ‘green’ materials that mitigates both the embodied and operational energy impact of a buildings lifecycle as buildings move towards NZEB energy performance standards.
Figure 1(a): Estimated life cycle energy including embodied energy (EE) and Figure 1(b): Estimated life cycle GWP breakdown including embodied global warming potential (EC) of a typical semi-detached home in Ireland over a 60 year lifespan
The results of this paper raised further questions such as whether it is best to design a residential building to be super-insulated or focus on installing a large amount of renewables. An analysis of this is currently under review for publication in a scientific journal with the analysis assessing the impact of future energy prices, electricity grid efficiency and electricity grid GWP intensity.
Future work will examine the real-time energy consumption and internal environmental data collected from urban and rural residential case study buildings which are being retrofitted to greater energy standards to assess the impact on the buildings lifecycle environmental and economic impact.