Project contact is Hongmei Gu at the Forest Products Laboratory
Summary
The FPL team is in charge of developing a full comparative LCA study for three multiple-story mass timber buildings and their concrete alternatives in the U.S. Northeast region, with Boston as the point location. Using these three comparative LCAs, this research will determine the GHG emissions reduction potential from mass timber use in the building sector for the U.S. region. This may increase potential for growth in wood utilization, timber harvest, and forest management practices through the market demands.
Many actions have been taken to decrease the operational energy use in buildings. However, with higher energy efficiency standards, the focus is increasingly shifting to energy demand for the production of building materials and the related greenhouse gas emissions. When moving towards zero emission buildings, the developments of more sustainable bearing structure are of interest. A six story housing complex was constructed in Gothenburg, Sweden in 2012 with a structure made of laminated veneer lumber floor elements and glue laminated beams and columns. The use of laminated veneer lumber has the advantage of being a light weight solution.
Building with wood in Norway is generally regarded as a carbon efficient solution, but the impact of additional materials such as glue and insulation can influence the overall results is of interest. Life cycle assessment is used as a tool to calculate the carbon footprint in the production of the main building materials of the structure. The goal of the assessment is to compare the wood structure as built with an equivalent steel and concrete structure and to optimise the use of materials. The scope of the assessment includes the foundation and elevator shaft, structural beams and columns and the floor elements. The results indicate that the steel and concrete alternative have about 35% higher greenhouse gas (GHG) emissions than the as built wood solution, but that almost half of the total emissions are related to the foundation and elevator shaft.
The anticipated growth and urbanization of the global population over the next several decades will create a vast demand for the construction of new housing, commercial buildings and accompanying infrastructure. The production of cement, steel and other building materials associated with this wave of construction will become a major source of greenhouse gas emissions. Might it be possible to transform this potential threat to the global climate system into a powerful means to mitigate climate change? To answer this provocative question, we explore the potential of mid-rise urban buildings designed with engineered timber to provide long-term storage of carbon and to avoid the carbon-intensive production of mineral-based construction materials.
In this paper, it is attempted to study possible sustainability solutions for building structures. In this context, comparisons are made between two load-bearing columns with different building materials – glued laminated timber and concrete – with regard to structural design, economic consequences and the emission of greenhouse gases. In terms of structural design, the results show that with small axial forces, glulam columns will result in smaller cross-sectional areas compared to concrete columns. However, at larger axial forces, concrete columns will result in smaller cross-sectional areas than glulam columns. An increased column length also means larger dimensions for glulam columns, but this does not always apply to concrete columns. With respect to environmental impact, it is shown that using glulam columns is the more environmentally friendly option. From an economic point of view, the cost estimates for glulam and concrete columns may vary depending on the country and the abundance of the construction material. In Sweden, a forest-rich country, it is shown that the costs for both column types are quite similar considering small axial loads. At higher axial loading, concrete is generally the cheaper alternative.
Sustainability and innovation are key components in the fight against climate change. Mass timber buildings have been gaining popularity due to the renewable nature of timber. Although research comparing mass timber buildings to more mainstream buildings such as steel is still in the early stages and therefore, limited. We are looking to determine the difference between carbon footprints of mass timber and traditional steel and concrete buildings. This is done with the intention of determining the sustainability and practicality of mass timber buildings.
Increasing the use of engineered wood products in the European Union can contribute to leveraging a shift towards a more emission-efficient production of construction materials. Engineered timber products have already been substituted for carbon and energy intensive concrete and steel-based building constructions, but they still lack the capacities and market demand to be more than just a niche market.
However, in the post-crisis period after 2008 the consumption of engineered wood products began rising in Europe. In this paper we analyse options for the future development of engineered wood products taking into consideration policy barriers and technical and environmental potentials for accelerating market introduction as part of a comprehensive scenario approach. For the European building sector we assessed an achievable potential for net carbon storage of about 46 million tonnes CO2-eqv. per year in 2030. To unlock this potential a bundle of instruments is necessary for increasing the market share for engineered wood products against the backdrop of existing policy instruments such as the gradual introduction of stricter rules for carbon emissions trading or more incentives for the voluntary use of innovative wood construction materials.
Journal of Sustainable Architecture and Civil Engineering
Summary
The objective of this paper is to report and analyse strategies for cost reduction, design processes, and procurement models of one wooden nearly Zero Energy Building (nZEB) in Norway. The building investigated in this paper is the Moholt Allmenning, a newly-built student accommodation located in Moholt, Trondheim. Interviews with the building's owner and the contractor were carried out to obtain information on the decision-making process during the procurement phase, the planning phase, and the execution phase. The results show that the environmental goal and the criteria set for the use of wood in the tender announcement were a critical driving force for choosing cross laminated timber (CLT) in the final design. The results also show that the cost of using CLT in student residences is competitive against using concrete and steel. Given the requirement of little greenhouse gas (GHG) emissions from materials production in nZEBs, the use of CLT is however a better choice.
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%.
Consuming over 40% of total primary energy, the built environment is in the centre of worldwide strategies and measures towards a more sustainable future. To provide resilient solutions, a simple optimisation of individual technologies will not be sufficient. In contrast, whole system thinking reveals and exploits connections between parts. Each system interacts with others on different scales (materials, components, buildings, cities) and domains (ecology, economy and social). Whole-system designers optimize the performance of such systems by understanding interconnections and identifying synergies. The more complete the design integration, the better the result.
In this book, the reader will find the proceedings of the 2016 Sustainable Built Environment (SBE) Regional Conference in Zurich. Papers have been written by academics and practitioners from all continents to bring forth the latest understanding on systems thinking in the built environment.
