Assessing Cross Laminated Timber (CLT) as an Alternative Material for Mid-Rise Residential Buildings in Cold Regions in China—A Life-Cycle Assessment Approach

Abstract

Abstract:Timber building has gained more and more attention worldwide due to it being a generic renewable material and having low environmental impact. It is widely accepted that the use of timber may be able to reduce the embodied energy of a building. However, the development of timber buildings in China is not as rapid as in some other countries. This may be because of the limitations of building regulations and technological development. Several new policies have been or are being implemented in China in order to encourage the use of timber in building construction and this could lead to a revolutionary change in the building industry in China. This paper is the first one to examine the feasibility of using Cross Laminated Timber (CLT) as an alternative solution to concrete by means of a cradle-to-grave life-cycle assessment in China. A seven-storey reference concrete building in Xi'an was selected as a case study in comparison with a redesigned CLT building. Two cities in China, in cold and severe cold regions (Xi'an and Harbin), were selected for this research. The assessment includes three different stages of the life span of a building: materialisation, operation, and end-of-life. The inventory data used in the materialisation stage was mostly local, in order to ensure that the assessment appropriately reflects the situation in China. Energy consumption in the operation stage was obtained from simulation by commercialised software IES TM , and different scenarios for recycling of timber material in the end-of-life are discussed in this paper. The results from this paper show that using CLT to replace conventional carbon intensive material would reduce energy consumption by more than 30% and reduce CO 2 emission by more than 40% in both cities. This paper supports, and has shown the potential of, CLT being used in cold regions with proper detailing to minimise environmental impact.

Energy Saving and Carbon Reduction in the Operation Stage of Cross Laminated Timber Residential Buildings in China

“…As mentioned above, on average, cooling and heating energy account for 35% of total energy consumption in China [7], and it can be estimated that at the national level, energy consumption in a story-story building with RC frames and CLT system are approximately 465.1 MJ/m 2 and 332.6 MJ/m 2 per annum, respectively. These results echo those outcomes from existing research [21][22][23]. Figure 9 presents the estimated results of energy consumption of RC and CLT buildings in 31 studied cities per year.…”

“…For the demolition stage, the destruction of a building is assumed to be 90% of the energy required in the erection phase [45]. The carbon sequestration of CLT is that one cubic meter of timber would store 1100 kg of CO2, and the on-site erection of CLT buildings is set to be 20 MJ/m 2 [22,32]. We can put this together on the basis of references above that, taking carbon storage in timber into consideration, the timber would store more carbon in itself than those emitted during the process of materialization and end-of-life stages, and more carbon reductions can be obtained if using CLT systems as an alternative to RC.…”

“…Liu et al made comparisons between two seven-story buildings that were constructed by RC and CLT in Severe Cold Region of China. They found that the energy consumptions for heating and cooling were 338 MJ/m 2 and 231.2 MJ/m 2 per annum, respectively [22]. Gustavsson et al studied the energy use and CO 2 emission of an eight-story wood-framed apartment building.…”

“…Gong et al made a comparison between concrete and timber as materials for frameworks in Beijing in various scenarios, and showed that concrete frames would consume 30% more energy compared to timber frames [35]. Liu et al made a building energy simulation in Harbin and Xi'an and demonstrated that using CLT as an alternative material to concrete is a feasible way to improve energy efficiency and reduced carbon emissions [22].…”

A Comparison of the Energy Saving and Carbon Reduction Performance between Reinforced Concrete and Cross-Laminated Timber Structures in Residential Buildings in the Severe Cold Region of China

“…Liu et al made comparisons between two seven-storey buildings constructed using RC and CLT in the severe cold region of China. They found that the energy consumption for heating and cooling was 338 MJ/m 2 and 231.2 MJ/m 2 per annum, respectively [27].…”