Comparative Life Cycle Assessment of Mass Timber and Concrete Residential Buildings: A Case Study in China

Comparative life cycle assessment of light frame timber and reinforced concrete masonry structural systems for single-family houses in Luxembourg

The building sector's significant greenhouse gas emissions and energy consumption present added challenges to meeting European climate commitments amidst rapid population growth. In Luxembourg, single-family houses dominate the residential buildings, noticeably contributing to construction waste and CO2 emissions. This study compares the environmental impacts of a three-story reinforced concrete masonry single-family house and an identical timber building in Luxembourg, emphasizing greenhouse gas emissions and embodied energy. A cradle-to-grave life cycle assessment was conducted using Building Information Modelling (BIM) models to analyze the global warming potential and primary energy requirements. Environmental product declarations from the producers and the ÖKOBAUDAT German database were used to determine the environmental impacts of the materials. The results show that the timber building outperforms the concrete building with a 43.5% lower global warming potential, while the concrete building demonstrates a 15.6% reduction in primary energy demand. This aligns with the average outcomes of seven similar studies discussed in this paper, at 33.2% and 4.7%, respectively. Moreover, the timber building is 78.6% lighter than the concrete one. When evaluating benefits and loads beyond the system boundary, the timber building provides 3.6 and 4 times greater advantages in terms of global warming potential and primary energy, respectively, compared to the reinforced concrete masonry building. Additionally, the study explores the impact of reusing the floors in the timber building. The cradle-to-grave LCA reveals that reusing the timber slabs improves the building's global warming potential and primary energy by 2.4% and 1.2%, respectively. However, when considering the benefits and loads beyond the system boundary, floor system reuse exhibits a 38.9% surge in global warming advantages while reducing primary energy benefits by 28.1%. The findings advocate for a policy promoting timber construction and reuse in Luxembourg, aiming to achieve the net-zero emission target by 2050.

Economic and environmental life cycle perspectives on two engineered wood products: comparison of LVL and GLT construction materials

The embodied carbon of building materials and the energy consumed during construction have a significant impact on the environmental credentials of buildings. The structural systems of a building present opportunities to reduce environmental emissions and energy. In this regard, mass timber materials have considerable potential as sustainable materials over other alternatives such as steel and concrete. The aim of this investigation was to compare the environment impact, energy consumption, and life cycle cost (LCC) of different wood-based materials in identical single-story residential buildings. The materials compared are laminated veneer lumber (LVL) and glued laminated timber (GLT). GLT has less global warming potential (GWP), ozone layer depletion (OLD), and land use (LU), respectively, by 29%, 37%, and 35% than LVL. Conversely, LVL generally has lower terrestrial acidification potential (TAP), human toxicity potential (HTP), and fossil depletion potential (FDP), respectively, by 30%, 17%, and 27%. The comparative outcomes revealed that using LVL reduces embodied energy by 41%. To identify which of these materials is the best alternative, various environmental categories, embodied energy, and cost criteria require further analysis. Therefore, the multi-criteria decision-making (MCDM) method has been applied to enable robust decision-making. The outcome showed that LVL manufacturing using softwood presents the most sustainable choice. These research findings contribute to the body of knowledge about the use of mass timber in construction.

Comparative Life Cycle Assessment of a Historic and a Modern School Building, Located in the City of Naoussa, Greece

Life Cycle Assessment is often applied as a methodological approach for evaluating the environmental performance and impact of the building sector, including building stock. In the present study, two school buildings, located in the city of Naoussa, N. Greece were analyzed, including a historic and a modern one. The survey concerned on-site inspection and documentation of the structures, data collection and analysis, Life Cycle Impact assessment, as well as comparative evaluation of the results. The objective was to indicate the constructional and performance characteristics of the buildings, as well as to comparatively evaluate their environmental performance and impact. Since historic school buildings still function as educational units, these aspects are crucial and may determine their future operation and use. For LCA, the expected life span of the buildings was taken into account (60 years for the modern school and 140 years for the historic one), as well as all life cycle stages (product, construction, use, end of life, beyond building life). Various indicators were assessed, such as Global Warming Potential (GWP), Fossil Fuel Consumption, Total Primary Energy, Non-Renewable Primary Energy. From the correlation of the results, it was asserted that although the two buildings present similar operational characteristics and needs, they have different environmental performances and impacts, mainly attributed to their different service life and structural characteristics. Although the operational GWP value of the historic building is higher (due to the extended life span), the embodied one is significantly lower (due to the natural materials used for its construction). Other indicators, such as fossil fuel consumption are also higher in the case of the modern school building, indicating that its environmental footprint is more intense.