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.
The building sector is increasingly identified as being energy and carbon intensive. Although the majority of emissions are linked to energy usage during the operation part of a building's life cycle, choice of construction materials could play a significant role in reducing greenhouse gas emissions and other environmental end-point damages. Increasing the use of wood products in buildings may contribute to the solution, but their environmental impacts are difficult to assess and quantify because they depend on a variety of uncertain parameters. The present cradle-to-gate life-cycle analysis (LCA) focuses exclusively on a glued-laminated wood product (glulam) produced from North American boreal forests located in the province of Quebec, Canada. This study uses primary data to quantify the environmental impacts of all necessary stages of products' life cycle, from harvesting the primary resources, to manufacturing the transformed product into glulam. The functional unit is 1 m3 of glulam. This is the first study based on primary data pertaining to Quebec's boreal forest. Quebec's boreal glulam manufacturing was compared with two other LCAs on glulam in Europe and the United States. Our results show that Quebec's glulam has a significantly smaller environmental footprint than what is reported in the literature. From an LCA perspective, there is a significant advantage to producing glulam in Quebec, compared with the European and American contexts. The same holds true in regard to the four end-point damage categories.
IOP Conference Series: Earth and Environmental Science
Cross laminated timber (CLT) has recently increased in use as a building material for low carbon design and is often applied in small and multi-story buildings. Several studies have shown lower fossil related greenhouse gas emission than alternatives, but the life cycle emissions vary substantially between different CLT producers. These emissions are mainly indirect and thus climate change mitigation could reduce these emissions. Previous research shows that that biofuels and carbon capture and storage (CCS) are technologies that have the potential to reduce the climate impacts of the CLT life cycle. This study assesses the impacts on climate change from CLT with these technologies within the framework of environmental product declarations (EPD). In the short run, switching to fossil free fuels provides a reduction in the carbon footprint of CLT. In the long run, CCS at the end-of-life of CLT buildings can provide a net negative carbon footprint over the life cycle. This assessment on the use of CLT is mainly related to the Sustainable Development Goal SDG9 Industries, innovation and infrastructure and the indicator for CO2 emissions per value added, so the assessment in this paper is mainly focused on this goal. SDG7 on affordable and clean energy and SDG15 Life on land are also relevant.
The improvement of environmental performance in building construction could be achieved by prefabrication. This study quantifies and compares the environmental impacts of a Concrete Glulam Framed Panel (CGFP): the basic configuration of this precast component consists in a Cross-Laminated Timber (CLT) frame structure supporting a thin reinforced concrete slab with an interior insulation panel and covered by finishing layers. The research investigates also alternative design of configuration with the substitution of different insulation materials in order to minimize the Embodied Energy and Carbon Footprint values.
The boundary of the quantitative analysis is “cradle to gate” including the structural support system; an IMPACT 2002+ characterization methodology is employed to translate inventory flows into impacts indicators.
Results present very low values for carbon footprint (60.63 kg CO2eq m-2) and the embodied energy values (919.44 MJ m-2) indicate this hybrid precast structure as a valid alternative building constructions and processes.
A detailed discussion of the outputs is presented, including the comparison of the environmental performances depending on different insulation materials.
In a former paper by the authors , the elastic behavior of Cross Laminated Timber (CLT) and timber panels having periodic gaps between lateral lamellae has been analyzed. A thick plate homogenization scheme based on Finite Elements computations has been applied. The predicted behavior was in agreement with experimental results. In this paper, simplified closed-form solutions are derived in order to avoid FE modeling. Both cases of narrow gaps of CLT panels and wide gaps of innovative lightweight panels are investigated. CLT and timber panels with gaps are modeled as a space frame of beams connected with wooden blocks. The contribution of both beams and blocks to the panel’s mechanical response is taken into account, leading to closed-form expressions for predicting the panel’s stiffnesses and maximum longitudinal and rolling shear stresses. The derived closed-form solutions are in agreement with the reference FE results and they can be used for practical design purposes.
The goal of the Timber Tower Research Project was to develop a structural system for tall buildings that uses mass timber as the main structural material and minimizes the embodied carbon footprint of the building. The research was applied to a prototypical building based on an existing concrete benchmark for comparison. The concrete benchmark building is the Dewitt-Chestnut Apartments, a 395-foot-tall, 42-story building in Chicago designed by SOM and built in 1965.
SOM's solution to the tall wooden building problem is the Concrete Jointed Timber Frame. This system relies primarily on mass timber for the main structural elements, with supplementary reinforced concrete at the connecting joints. This system plays to the strengths of both materials. The result is an efficient structure that could compete with reinforced concrete and steel while reducing the carbon footprint by 60 percent to 75 percent.