By: Morteza Nikravan, Water & Environment Specialist, EDGE Expert
Since the oil crises in the 1970s, a significant concern within building design and operation has been to limit the need for operational energy and hence the demand for oil-based heating and electricity. In terms of the scale of this resource use and environmental degradation, the contributions of buildings, and the built environment to global totals are significant. According to UNEP’s Sustainable Buildings and Climate Initiative, buildings account for 40% of global energy use, 38% of global greenhouse gas emissions, and 40% of the solid waste streams in developed countries. When moving up to the city level, the impacts are more substantial: an estimated 70% of greenhouse gas emissions and over 66% of global electricity use emanate from urban activities.
Increasing regulatory requirements on the energy performance of buildings have taken the building design to ever more sophisticated levels where additional materials and technologies are used to reduce the energy consumed in operating the building and in providing for the needs of the users. This development of buildings towards increasingly complicated products coupled with relatively long product service lives makes LCA a prominent part of the environmental evaluation of buildings. LCAs within the building sector are mainly used to compare different choices of shape, design, or material at a single building level. Either the comparison is made with the potential impacts of alternative design solutions, or the results are evaluated against a benchmark performance of the specific type of building and use. The application of LCA methodologies to buildings has strengthened building sustainability assessment systems (e.g. BREEAM, DGNB) by incorporating cradle-to-grave thinking; while these systems, in turn, have contributed significantly to further development of LCA standards and methodologies.
As illustrated in Fig. 1, the ISO standard distinguishes the methodological framework of LCA from its different applications, which are multiple such as product development, Ecolabelling, carbon footprint, and other footprints. Applications of LCA are treated in separate publications from the standard organization; the LCA framework operates with four different phases, Goal and scope definition, Inventory analysis, Impact assessment, and Interpretation.
Fig. 1. The framework of LCA modified from the ISO 14040 standard
It is interesting to the researcher that the number of studies on LCA and construction is increasing dramatically. The publication of LCA articles on building materials and construction has been growing steadily since 1994, and its intensity has grown since 2013.
Fig. 2. The number of articles during 1994-2016
The study of LCA in various fields is shown in Fig. 3 in terms of the number of works; as it can be seen from this figure, environmental sciences with 709; environmental engineering with 685, building and construction technology with 545 and civil engineering with 492 works have the most sections. The critical point is the interdisciplinary nature of the use of LCA in engineering, which has emerged between the environment and civil engineering, mechanics, and industry.
Fig. 3. Number of articles on LCA in various fields of study
The connection between LCA and studied keywords is illustrated in Fig 4. It could be found that the LCA is more connected to embodied energy, recycling, and building materials
Fig. 4. Connection of keywords in research studies and clustering subjects
The modeling of increasingly complex product systems and the proliferation of LCI (Life Cycle Inventory) data and impact assessment methodologies created a need for dedicated LCA software. Table 1 shows some of the widely used software for LCA. In OpenLCA, which is a free LCA software, you could use different databases (such as ecoinvent) and evaluate different methods (such as ReCiPe)
Table 1. Software for performing LCA (non-exhaustive list)
LCA software (such as SimaPro or OpenLCA) includes tools for drawing Sankey diagrams. A Sankey diagram depicts flows of impacts, where the width of each flow pictured is based on the number of influences. So, the impacts could be analyzed according to a different process. The OpenLCA Project creates modular software for life cycle analysis and sustainability assessments.
Fig .5. An example of output Sankey diagrams in openLCA
Besides the above software, some tools are exclusively designed for LCA analysis in buildings. Tally®, which is an LCA module in Autodesk’s group of software for buildings, accounts for the full cradle-to-grave life cycle, according to EN 15978. It utilizes a custom-designed LCA database developed in GaBi 6 and using GaBi databases, consistent with LCA standards ISO 14040-14044.
Fig .6. an example of Tally outputs
One Click LCA™, developed by Bionova®, is an LCA and LCC (Life-Cycle Costing) software that allows to design greener buildings, to create Environmental Product Declarations (EPD) for building materials and to earn valuable certification credits, including LEED v4’s MRc1 Building Life-Cycle Impact Reduction, and BREEAM Mat 01 Life cycle impacts.
Fig .7. an example of One Click LCA outputs
The tool works as a plugin by importing data from Revit or BIM model, gbXML Energy model, Excel, or use the manual import within the cloud software itself and obtain a ready-made report.
The Tally® application works directly in Revit, while One Click LCA™ analyzes in the cloud. The tools present a different procedure for materials selection and method of calculation. One Click LCA™ considers materials separately, and the list of products is organized by assessment method and by country source; Tally® allows to choose how to consider a component and the layer of inner materials with a strict connection and cohesion to Revit, even if the available list of products is limited. Both tools allow a comparison of construction technology and choice of materials, giving exhaustive reports, charts for evaluating the impacts of products, documents at each stage of life span, and also spreadsheets for further data elaboration (especially in One Click LCA™).
Forth, K., Braun, A., & Borrmann, A. (2019, August). BIM-integrated LCA-model analysis and implementation for practice. In IOP Conference Series: Earth and Environmental Science (Vol. 323, No. 1, p. 012100). IOP Publishing.
Hauschild, M. Z., Rosenbaum, R. K., & Olsen, S. I. (2018). Life cycle assessment. Springer.
نیکروان, مرتضی؛ علی اکبر رمضانیان پور و رضا مکنون، ۱۳۹۷، بررسی و تحلیل تحقیقات صورت گرفته در زمینه کاربرد ابزار ارزیابی چرخه حیات (LCA) در مصالح ساختمانی و ساخت و ساز، سومین کنفرانس بین المللی و هفتمین کنفرانس ملی مصالح و سازه های نوین در مهندسی عمران، همدان، دانشگاه بوعلی سینا همدان، https://www.civilica.com/Paper-NCNMS07-NCNMS07_097.html