Life cycle assessment of roads: Exploring research trends and harmonization challenges

The transparency, heterogeneity and hypotheses considered in the calculation of the environmental impacts of roads remain as barriers in the identification of low-carbon solutions. To overcome this gap, the study presents an analysis of 94 papers obtained in a systematic literature review of the Scopus, Science direct, Mendeley, Springer Link, and Web of Science databases. From a total of 417 road case studies, only 18% were found to be fully transparent, reproducible, and likely to present reliable results. The road design parameters of the speed limit were provided in 11% of cases and the average annual daily traffic data were provided in 42%. Limited data were found for the dimensions of road elements such as the number (77%) and width of lanes (33%), shoulders (15%), footpaths (5%), berm (1%) or foreslope (4%). The source of the life cycle inventory was presented in 57% of the case studies, impact assessment method was indicated in 22%, and the software utilized was stated in 50%. Lack of information was observed in the description of the type of materials employed in road projects. In addition, the large heterogeneity in the definitions of the functional unit, system boundary and in the reference study period of repair, replacement, rehabilitation or end-of-life for both flexible and rigid pavement does not support the identification of the most environmentally friendly solution. Based on results of the analsis,several recommendations for design parameters and life cycle assessment aspects are proposed to support a harmonized calculation of the environmental impacts of road projects.publishedVersio

Existing benchmark systems for assessing global warming potential of buildings – Analysis of IEA EBC Annex 72 cases

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO2e/m2/y, whereas reference values are found between 20-80 kg CO2e/m2/y. Possible embodied target- and reference values are found between 1-12 kg CO2e/m2/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems.publishedVersio

Eco-efficiency and Performance Strategies in Construction and Demolition Waste Recycling Systems

This thesis studies the Danish and Norwegian recycling systems for construction and demolition (C&D) waste. The architectural, Engineering and Construction (AEC) industry is a major contributor to societies waste production; accounting for approximately 40% of the waste production. It is therefore important to manage the C&D waste effectively to move society towards sustainability. This study applies the Industrial Ecology paradigm. This involved multidisciplinary approach, spanning the fields of Industrial Ecology, Systems Engineering and Organizational and Social Studies. The scope of this thesis is threefold. The first scope is to get a better understanding of the processes that are taking place within the socio-technical sphere of a recycling system. Second, what is the nature of the C&D waste and what are the environmental impacts from the various waste fractions. Third, how can this information be used to improve recycling systems for C&D waste. The study show that the suggestions in the National Action Plan and the corresponding policies are eco-effective, but that the environmental impact is very transport dependent. The study also shows that there is a great need to focus on future waste composition in the design of recycling systems for C&D waste. However, such waste projections are difficult to perform due to poor data availability. There is a need for making more qualified decisions on environmental issues, with regard to long term management of such recycling systems. Long term models combined with environmental and economic information can make a powerful tool for such analysis

Evaluation of BIM based LCA in early design phase (low LOD) of buildings

Building Information Modelling (BIM) is a convenient tool that is capable of collecting information throughout the whole life cycle of a building in one platform. The evolution in the digital BIM model in early design stages is not standardized, but Level of Development (LOD) is a concept that systematically structures the design processes divided into five levels. LOD is assessed in this paper as an opportunity to enhance the calculation of the environmental impacts in different early design stages more efficiently, using the methodology Life Cycle Assessment (LCA). Enlightening the building elements that contribute to highest release of CO 2, permits early building material selection. This facilitates a pathway towards sustainable and environmentally friendly buildings. This study evaluates BIM based LCA in early design stages (low LOD) through literature reviews and a case study. This papers' case study executes LCAs at different LOD levels using the LCA software One Click LCA (OCL). Assessments in LOD 200, LOD 300, LOD 350 and an additional LOD 350 were utilized. The additional LOD 350 was deployed when LCA experts had implemented changes within OCL. Moreover, a concretized suggestion where today's unpredictable development of BIM becomes part of a LOD framework is proposed

Parametric Design to Maximize Solar Irradiation and Minimize the Embodied GHG Emissions for a ZEB in Nordic and Mediterranean Climate Zones

This work presents a validated workflow based on an algorithm developed in Grasshopper to parametrically control the building’s shape, by maximizing the solar irradiation incident on the building envelope and minimizing the embodied emissions. The algorithm is applied to a zero-emission building concept in Nordic and Mediterranean climate zones. The algorithm enables conducting both energy and environmental assessments through Ladybug tools. The emissions embodied in materials and the solar irradiation incident on the building envelope were estimated in the early design stage. A three-steps optimization process through evolutionary solvers, such as Galapagos (one-objective) and Octopus (multi-objective), has been conducted to shape the most environmentally responsive ZEB model in both climates. The results demonstrated the replicability of the algorithm to optimize the solar irradiation by producing an increment of solar incident irradiation equal to 35% in the Mediterranean area, and to 20% in the Nordic climate. This could contribute to compensate the additional 15% of emissions due to the higher quantities of employed materials in the optimized design. The developed approach, which is based on the parametric design principles for ZEBs, represents a support instrument for designers to develop highly efficient energy solutions in the early design stagespublishedVersio

Gap between simplified and detailed calculation of the environmental impacts of road mixtures

In order to reach the COP21 objectives, solutions with low carbon contents must be used in road projects. However, the identification of the best materials to be implemented in the wearing course of roads is a daily problem faced by stakeholders. To overcome this knowledge gap, the present study demonstrates the environmental impacts of 120 mixtures calculated with simplified and detailed hypotheses and input data. Even though the variability of inputs significantly influences the impacts of the mixtures and do not allow for the identification of the best solutions, on average, warm mix asphalt presented lower impacts than hot mix asphalt or concrete

The effect of insulation thickness on lifetime CO2 emissions

This paper assesses the total carbon emissions of a single-family home designed and built for Norwegian conditions, according to current standards (TEK 17), using an LCA approach. Various combinations of insulation thicknesses are assessed to identify which combination is most efficient in lowering the lifetime emissions as well as in which part of the building envelope additional insulation is most efficient in reducing the lifetime greenhouse gas emissions of the building. Overall, increased insulation resulted in lower lifetime emissions; the increased embodied emissions generally being outweighed by the energy savings resulting from the increased insulation thickness. The location of the insulation is the factor that was found to have the largest impact on the lifetime emissions. When increasing the insulation thickness from 100-500 mm, changing only one component at a time, the operational emissions were most sensitive to the insulation thickness in the walls, with a 26 % decrease compared to 7% and 3% for the roof and floor respectively. The most efficient cases tended to have little insulation in the floor (100 - 150 mm) and relatively high insulation thickness in the wall (350 mm). The most variable component was the roof, varying from 150 to 400 mm