Forests can help mitigate climate change in different ways, such as by storing carbon in forest ecosystems, and by producing a renewable supply of material and energy products. We analyse the climate implications of different scenarios for forestry, bioenergy and wood construction. We consider three main forestry scenarios for Kronoberg County in Sweden, over a 201-year period. The Business-as-usual scenario mirrors today's forestry while in the Production scenario the forest productivity is increased by 40% through more intensive forestry. In the Set-aside scenario 50% of forest land is set-aside for conservation. The Production scenario results in less net carbon dioxide emissions and cumulative radiative forcing compared to the other scenarios, after an initial period of 30–35 years during which the Set-aside scenario has less emissions. In the end of the analysed period, the Production scenario yields strong emission reductions, about ten times greater than the initial reduction in the Set-aside scenario. Also, the Set-aside scenario has higher emissions than Business-as-usual after about 80 years. Increasing the harvest level of slash and stumps results in climate benefits, due to replacement of more fossil fuel. Greatest emission reduction is achieved when biomass replaces coal, and when modular timber buildings are used. In the long run, active forestry with high harvest and efficient utilisation of biomass for replacement of carbon-intensive non-wood products and fuels provides significant climate mitigation, in contrast to setting aside forest land to store more carbon in the forest and reduce the harvest of biomass.
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
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.
This paper focused on energy consumption and carbon emission for heating and cooling during a building’s operation stage, and examined the energy effects of using Cross Laminated Timber (CLT) as an alternative building material to reinforced concrete (RC) in China’s 31 key cities located in different climate zones. The authors designed two seven-story residential buildings, which were constructed with RC framed and CLT systems, separately. This was followed by simulating the energy consumption using commercialized software IESTM under the different climate zones and calculating the carbon emissions. Comparisons were made between RC and CLT systems buildings on the basis of simulation data. The results show that the estimated energy consumption and carbon emission in CLT buildings are much lower than that of RC buildings in all studied cities, which indicates that CLT systems have good potential in reducing carbon emission and saving energy consumption compared to RC. The energy consumptions and carbon emissions in both concrete and CLT buildings are closely related to the climate zones. Buildings in Severe Cold and Cold Regions consumed the most energy and released more carbon. At the national level, the estimated energy consumption at the operation stage, in the studied building with RC frames and CLT system was approximately 465.1 MJ/m2 and 332.6 MJ/m2 per annum, respectively. Despite vast differences in China’s climate zones, the effects of energy saving and carbon reduction potentials of CLT buildings show little relationship to the climate zone. CLT buildings may result in a weighted 29.4% energy saving, which equals 24.6% carbon reductions, compared with RC buildings at the operation stage at national level, although it may vary in different climate zones.
Relying on China’s national standard “Standard for Building Carbon Emission Calculation” and related reports published by the Athena Institute, this report calculates the life cycle carbon emissions of wood buildings in China. The study collects basic information of all the projects, such as quantity of building materials, building envelope, energy system and so on. Calculations are conducted for 7 projects from the aspects of product stage, transportation stage, construction stage, operational energy and demolition stage
IOP Conference Series: Earth and Environmental Science
Summary
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.
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