International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
August 4–7, 2013, Portland, Oregon, USA
As sustainable building design practices become more prevalent in today’s construction market, designers are looking to alternative materials for novel design strategies. This paper presents a case study comparing the sustainability performance of cross laminated timber (CLT) and reinforced concrete. A comparative sustainability assessment of cross laminated timber and concrete, considering economic, environmental, and social aspects was performed. Environmental impact is measured in terms of CO2 equivalent, economic impact is measured with total sector cost (including sector interdependencies), and qualitative metrics were considered for social impact. In order to conduct an accurate performance comparison, a functional unit of building facade volume was chosen for each product. For this paper, several end-of-life strategies were modeled for CLT and concrete facades. To understand environmental, economic, and social impact, three different scenarios were analyzed to compare performance of both CLT and concrete, including cradle to gate product manufacturing, manufacturing with landfill end-of-life, and manufacturing with recycling end-of-life. Environmental LCA was modeled using GaBi 5.0 Education Edition, which includes its own database for elements including materials, processes, and transportation. To compare the economic impact, Carnegie Mellon’s EIO-LCA online tool is used. Finally, social life cycle impact was considered by identifying process attributes of both products that affect the social domain. Based on this analysis, the use of CLT has a significantly lower environmental impact than concrete, however there are additional costs.
This paper aims to investigate the energy saving and carbon reduction performance of cross-laminated timber residential buildings in the severe cold region of China through a computational simulation approach. The authors selected Harbin as the simulation environment, designed reference residential buildings with different storeys which were constructed using reinforced concrete (RC) and cross-laminated timber (CLT) systems, then simulated the energy performance using the commercial software IESTM and finally made comparisions between the RC and CLT buildings. The results show that the estimated energy consumption and carbon emissions for CLT buildings are 9.9% and 13.2% lower than those of RC buildings in view of life-cycle assessment. This indicates that the CLT construction system has good potential for energy saving when compared to RC in the severe cold region of China. The energy efficiency of residential buildings is closely related to the height for both RC and CLT buildings. In spite of the higher cost of materials for high-rise buildings, both RC and CLT tall residential buildings have better energy efficiency than low-rise and mid-rise buildings in the severe cold region of China.
The purpose of this research is to evaluate the environmental performance of various timber constructions that have been realised within intensively utilised area in recent years. The appraisal is carried out by means of life cycle assessment (LCA) and covers different timber constructions, mainly the multi-storey building. The ultimate goal is to compare their environmental performance to the outcomes of other constructions like reinforced concrete (RC) and steel construction (SC).
The environmental burdens caused by constructions are evaluated based on the framework of LCA. First, the material inventory of selected building projects is established. The scope is emphasised on the primary structural elements such as columns, beams, deck, load-bearing wall and roof. Secondary components, facility and decoration are eliminated out of the research boundary. Based on the material inventory, the impact assessment is carried out to preliminarily calculate the embodied outcome of the timber constructions. The environmental implications of structural elements during early life cycle stages are evaluated. Then, the effect of both disposal and material recycling is integrated in the LCA, including reuse or recovery of the structural wooden components. The LCA takes into account different disposal scenarios associated with construction and demolition waste (C&DW). By doing so, the LCA is the so-called ‘from cradle to gate’ and ‘gate to cradle’, without consideration upon the using phase. Among numerous environmental indictors, this research quantifies and discusses the energy consumption and global warming potential (GWP) of the timber buildings only.
The five-storey timber building located in urban context is a pioneer project in Taiwan. This building applies crosslaminated-timber (CLT) as the primary structural elements and takes over tremendous loading circumstances. It demonstrates not only the engineering feasibility of CLT for architectural design but also the utilising compatibility of wooden house in urban context.
The environmental evaluation proofs the ecological efficiency of timber buildings. In addition, this study compares the environmental performance of timber constructions and other materials. Alternative building models made of RC and steel are developed and intended for further LCA. The LCA results demonstrate that timber constructions cause significantly less impacts than RC and SC do. Timber constructions exhibit carbon sequestration effect, which is unique among three materials. Meanwhile, timber constructions consume only about 20% energy of the RC and SC. While possessing similar form and functionality, timber constructions exhibit better eco-efficiency compared to other generally used materials. When the material recycling is taken into account, the life-cycle eco-efficiency of timber structures is further significant. Wooden constructions can be energy-neutral or even energy-productive, depending on the recycling strategies.
This paper reports on a study examining the potential of reducing greenhouse gas (GHG) emissions from the building sector by substituting multi-storey steel and concrete building structures with timber structures. Life cycle assessment (LCA) is applied to compare the climate change impact (CC) of a reinforced concrete (RC) benchmark structure to the CC of an alternative timber structure for four buildings ranging from 3 to 21 storeys. The timber structures are dimensioned to meet the same load criteria as the benchmark structures. The LCA comprises three calculation approaches differing in analysis perspective, allocation methods, and modelling of biogenic CO2 and carbonation of concrete. Irrespective of the assumptions made, the timber structures cause lower CC than the RC structures. By applying attributional LCA, the timber structures are found to cause a CC that is 34-84% lower than the RC structures. The large span is due to different building heights and methodological assumptions. The CC saving per m2 floor area obtained by substituting a RC structure with a timber structure decrease slightly with building height up to 12 storeys, but increase from 12 to 21 storeys. From a consequential LCA perspective, constructing timber structures can result in avoided GHG emissions, indicated by a negative CC. Compared to the RC structures, this equal savings greater than 100%.