Australian Life Cycle Assessment Society conference
The use of timber construction products and their environmental impacts is growing in Europe. This paper examines the LCA approach adopted in the European CEN/TC350 standards, which are expected to improve the comparability and availability of Environmental Product Declarations (EPDs). The embodied energy and carbon (EE and EC) of timber products is discussed quantitatively, with a case study of the Forte building illustrating the significance of End-of-Life (EoL) impacts. The relative importance of timber in the context of all construction materials is analysed using a new LCA tool, Butterfly. The tool calculates EE and EC at each life cycle stage, and results show that timber products are likely to account for the bulk of the EoL impacts for a typical UK domestic building.
The research presents a Carbon Value Engineering framework. This is a quantitative value analysis method, which not only estimates cost but also considers the carbon impact of alternative design solutions. It is primarily concerned with reducing cost and carbon impacts of developed design projects; that is, projects where the design is already a completed to a stage where a Bill of Quantity (BoQ) is available, material quantities are known, and technical understanding of the building is developed.
This research demonstrates that adopting this integrated carbon and cost method was able to reduce embodied carbon emissions by 63-267 kgCO2-e/m2 (8-36%) when maintaining a concrete frame, and 72-427 kgCO2-e/m2 (10-57%) when switching to a more novel whole timber frame. With a GFA of 43,229 m2 these savings equate to an overall reduction of embodied carbon in the order of 2,723 – 18,459 tonnes of CO2-e. Costs savings for both alternatives were in the order of $127/m2 which equates to a 10% reduction in capital cost.
For comparison purposes the case study was also tested with a high-performance façade. This reduced lifecycle carbon emissions in the order of 255 kgCO2-e/m2, over 50 years, but at an additional capital cost, due to the extra materials. What this means is strategies to reduce embodied carbon even late in the design stage can provide carbon savings comparable, and even greater than, more traditional strategies to reduce operational emissions over a building’s effective life.
The objective of this project was to quantify and compare the environmental impacts associated with alternative designs for a typical North American mid-rise office building. Two scenarios were considered; a traditional cast-in-place, reinforced concrete frame and a laminated timber hybrid design, which utilized engineered wood products (cross-laminated timber (CLT) and glulam). The boundary of the quantitative analysis was cradle-to-construction site gate and encompassed the structural support system and the building enclosure. Floor plans, elevations, material quantities, and structural loads associated with a five-storey concrete-framed building design were obtained from issued-for-construction drawings. A functionally equivalent, laminated timber hybrid design was conceived, based on Canadian Building Code requirements. Design values for locally produced CLT panels were established from in-house material testing. Primary data collected from a pilot-scale manufacturing facility was used to develop the life cycle inventory for CLT, whereas secondary sources were referenced for other construction materials. The TRACI characterization methodology was employed to translate inventory flows into impact indicators. The results indicated that the laminated timber building design offered a lower environmental impact in 10 of 11 assessment categories. The cradle-to-gate process energy was found to be nearly identical in both design scenarios (3.5 GJ/m2), whereas the cumulative embodied energy (feedstock plus process) of construction materials was estimated to be 8.2 and 4.6 GJ/m2 for the timber and concrete designs, respectively; which indicated an increased availability of readily accessible potential energy stored within the building materials of the timber alternative.
This series highlights five whole building life cycle assessments (WBLCAs) of buildings incorporating the building material known as cross-laminated timber (CLT) into some or all of their structure, using a primary cradle-to-grave system boundary. This case study series will serve as an educational resource for academics, professionals, and CLT project stakeholders. While there is some uncertainty about the best way to reduce greenhouse gas emissions from architecture and construction, using CLT and other wood building materials is one possible means to reduce the emissions associated with a building’s materials. When forests are managed sustainably, wood construction materials can contribute to climate change mitigation goals as an indefinite carbon store and as a replacement of other fossil-fuel intensive materials. WBLCA is an assessment method to estimate the environmental impacts of buildings; this series offers insight into the current possibilities and limitations of WBLCA for CLT buildings. The series begins with background information on WBLCA methods and CLT, a review of previously published CLT building WBLCAs, and a life cycle assessment of an individual CLT wall element using the WBLCA softwares Tally® and Athena Impact Estimator for Buildings (Athena IE).
Project contact is Angelique Pilon at the University of British Columbia
The pilot uses whole-building life cycle assessments (WBLCA) to identify major contributors to embodied carbon impacts. More importantly, the project conducts a critical analysis of the procedural requirements, information gaps, systemic barriers and other challenges for project teams seeking to use LCA as an effective tool in reducing their environmental impacts. The second phase of the Embodied Carbon Pilot project builds on the experiences and learning of Phase 1 while addressing a more common and replicable building typology. The first year, we used mass timber buildings at the University of British Columbia for the pilot LCAs and developed a protocol/strategy for adapting project information into the appropriate bill-of-materials (BOM) format for input into LCA tools, while identifying procedural challenges and barriers and variations of different material take-off methodologies and LCA tools. This second year, we will target mid-rise, multi-unit residential buildings (MURBs), a common and growing building type throughout British Columbia. Mid-rise MURBS are between 4 and 8 stories and typically use wood as one of the primary construction materials: stick-frame construction for projects under 6-stories or an increasing number of mass timber projects.
IOP Conference Series: Earth and Environmental Science
According to the predictions of United Nations (2017) there are more than 7 billion people on Earth and this number will reach 9.7 billion by 2050. Today, most of the population lives in the urban areas and the rapid growth entails more construction in a housing sector. Since the industrial revolution the world has experienced countless technological attainments and on the other hand risky increase in natural resources use, energy consumption, greenhouse gases emission, ozone depletion, toxification and global temperature rising. The question how the cities can respond to urban growth is related to the sustainable goals of Agenda 2030. This research discusses potential of the usage of timber as construction material and it also brings the answer to this question. The wood is 100% renewable, recyclable and nontoxic material with capacity to absorb CO2 and perform low embodied energy. The increase of timber use in the construction contributes to sustainable development and to the reduction of waste, CO2 emission, as well as energy consumption. The aim of this paper is to discuss the advantages of using timber as a sustainable solution in urban context, in comparison with most commonly used concrete. The findings demonstrate the value of timber as sustainable construction material.