The building sector plays a key role in energy transition and carbon reduction while capturing the dynamic characteristics (e.g. materials, energy performance, and environmental impact) of building... Show moreThe building sector plays a key role in energy transition and carbon reduction while capturing the dynamic characteristics (e.g. materials, energy performance, and environmental impact) of building stock is a great challenge during the gradual process. This study presents a bottom-up dynamic building stock model that links dynamic material flow analysis with building energy modeling. The environmental impact of material and energy requirements is assessed by considering future electricity mix. The model is applied to evaluate the pathways to the climate-neutral energy supply of residential building stock in the Netherlands by 2050. Results show that space heating demand decreases by about 2/3 by 2050, while the energy for hot water increases to 92% of space heating demand. 80% of public grid electricity for appliances and lighting can be potentially substituted if rooftop photovoltaic (PV) systems are installed on 50% of renovated buildings and all the new buildings. Greenhouse gas (GHG) emissions of operational energy are reduced by approximately 60-90%, depending on the electricity mix. Annual GHG emissions from material production are not as important as those related to operational energy. Insulation materials account for a large proportion of the carbon footprint of material production. The model has a high spatial and temporal resolution and can be linked with local energy source availability (e.g. buildings or neighborhoods) to provide more accurate support for policymaking. Show less
Yang, X.; Hu, M.; Zhang, C.; Steubing, B.R.P. 2022
Building stock growth around the world drives extensive material consumption and environmental impacts. Future impacts will be dependent on the level and rate of socioeconomic development, along... Show moreBuilding stock growth around the world drives extensive material consumption and environmental impacts. Future impacts will be dependent on the level and rate of socioeconomic development, along with material use and supply strategies. Here we evaluate material-related greenhouse gas (GHG) emissions for residential and commercial buildings along with their reduction potentials in 26 global regions by 2060. For a middle-of-the-road baseline scenario, building material-related emissions see an increase of 3.5 to 4.6 Gt CO2eq yr-1 between 2020-2060. Low- and lower-middle-income regions see rapid emission increase from 750 Mt (22% globally) in 2020 and 2.4 Gt (51%) in 2060, while higher-income regions shrink in both absolute and relative terms. Implementing several material efficiency strategies together in a High Efficiency (HE) scenario could almost half the baseline emissions. Yet, even in this scenario, the building material sector would require double its current proportional share of emissions to meet a 1.5 degrees C-compatible target.Building construction causes large material-related emissions which present a serious decarbonization challenge. Here, the authors show that the building material sector could halve emissions by increasing efficiency until 2060 but even then its emissions would be twice as high as needed to meet the 1.5 degrees C target. Show less
Zhong, X.; Hu, M.; Deetman, S.P.; Dias Rodrigues, J.F.; Lin, H.; Tukker, A.; Behrens, P.A. 2021
Energy efficiency plays an essential role in energy conservation and emissions mitigation efforts in the building sector. This is especially important considering that the global building stock is... Show moreEnergy efficiency plays an essential role in energy conservation and emissions mitigation efforts in the building sector. This is especially important considering that the global building stock is expected to rapidly expand in the years to come. In this study, a global-scale modeling framework is developed to analyze the evolution of building energy intensity per floor area during 1971-2014, its relationship with economic development, and its future role in energy savings across 21 world regions by 2060. Results show that, for residential buildings, while most high-income and upper-middle-income regions see decreasing energy intensities and strong decoupling from economic development, the potential for further efficiency improvement is limited in the absence of significant socioeconomic and technological shifts. Lower-middle-income regions, often overlooked in analyses, will see large potential future residential energy savings from energy intensity reductions. Harnessing this potential will include, among other policies, stricter building efficiency standards in new construction. For the commercial sector, during 1971-2014, the energy intensity was reduced by 50% in high-income regions but increased by 193% and 44% in upper-middle and lower-middle-income regions, respectively. Given the large energy intensity reduction potential and rapid floor area growth, commercial buildings are increasingly important for energy saving in the future. (C) 2021 The Author(s). Published by Elsevier Ltd. Show less
Zhang, C.; Hu, M.; Laclau, B.; Garnesson, T.; Yang, X.; Tukker, A. 2021
Buildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate... Show moreBuildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate construction and demolition waste as feedstock for residential building energy renovation by over-cladding the walls of old buildings. By conducting life cycle assessment and life cycle costing using the payback approach, this study aims to explore the life cycle performance of energy conservation, carbon mitigation, and cost reduction of the PCE system in three European member states: Spain, the Netherlands, and Sweden. The results show that the energy payback periods for Spain, the Netherlands, and Sweden were 20.45 years, 17.60 years, 19.95 years, respectively, and the carbon payback periods were 23.33 years, 16.78 years, and 8.58 years, respectively. However, the financial payback periods were less likely to be achieved within the building lifetime, revealing that only the Swedish case achieved a payback period within 100 years (83.59 years). Thus, circularity solutions were considered to shorten the PCE payback periods. Using secondary materials in PCE fabrication only slightly reduced the payback period. However, reusing the PCE considerably reduced the energy and carbon payback periods to less than 6 years and 11 years, respectively in all three cases. Regarding cost, reusing the PCE shortened the Swedish payback period to 29.30 years, while the Dutch and Spanish cases achieved investment payback at 42.97 years and 85.68 years, respectively. The results can be extrapolated to support the design of sustainable building elements for energy renovation in Europe. Show less
Zhang, C.; Hu, M.; Sprecher, B.; Yang, X.; Zhong, X.; Li, C.; Tukker, A. 2021
Around 35% of the buildings in Europe are over 50 years old and almost 75% of the building stock is energy-inefficient. A European project VEEP is developing an innovative prefabricated concrete... Show moreAround 35% of the buildings in Europe are over 50 years old and almost 75% of the building stock is energy-inefficient. A European project VEEP is developing an innovative prefabricated concrete element (PCE) system to improve the thermal performance of new buildings (PCE1) and old buildings (PCE2). This study focused on retrofitting of old buildings via over-cladding of the building envelope with PCE2. This study aims to from a building owner/consumer’s perspective to explore the life cycle economic performance of the PCE2 system at an early stage and associated cost optimization strategies under the European context. This study tries to answer four questions: 1) whether the use of the PCE2 leads to an economic advantage over a specific life cycle of an existing building. 2) what is the biggest cost stressor in the life cycle of a PCE2? 3) the potential route for further cost optimization. and 4) how would the discount rate affect the life cycle costs, especially when Europe has entered a negative rate age? A typical apartment building in the Netherlands is selected as the case study for dynamic thermal simulation, in which the heating and cooling energy demands before and after refurbishment with PCE2 will be evaluated. By employing environmental life cycle costing (LCC), the life cycle costs over 40 years and associated strategy for cost optimization will be investigated. This research not only unveils meaningful financial implications on resource-efficient building energy retrofitting in Europe but also provides insight on methodological dilemmas within the application of LCC. Show less
Zhang, C.; Hu, M.; Yang, X.; Miranda Xicotencatl, B.; Sprecher, B.; Di Maio, F.; ... ; Tukker, A. 2020
Urban mining from construction and demolition waste (CDW) is highly relevant for the circular economy ambitions of the European Union (EU). Given the large volumes involved, end-of-life (EoL)... Show moreUrban mining from construction and demolition waste (CDW) is highly relevant for the circular economy ambitions of the European Union (EU). Given the large volumes involved, end-of-life (EoL) concrete is identified as one of the priority streams for CDW recycling in most EU countries, but it is currently largely downcycled or even landfilled. The European projects C2CA and VEEP have proposed several cost-effective technologies to recover EoL concrete for new concrete manufacturing. To understand the potential effects of large-scale implementation of those recycling technologies on the circular construction, this study deployed static material flow analysis (MFA) for a set of EoL concrete management scenarios in the Netherlands constructed by considering the development factors in two, technological and temporal dimensions. On the technological dimension, three treatment systems for EoL concrete management, namely: business-as-usual treatment, C2CA technological system and VEEP technological system were investigated. On the temporal dimension, 2015 was selected as the reference year, representing the current situation, and 2025 as the future year for the prospective analysis. The results show that the development of cost-effective technologies has the potential to improve the share of recycling (as opposed to downcycling) in the Netherlands from around 5% in 2015 up to 22%~32% in 2025. From the academic aspect, the presented work illustrates how the temporal dimension can be included in the static MFA study to explore the potential effects in the future. Show less
Zhang, C.; Hu, M.; Yang, X.; Amati, A.; Tukker, A. 2020
The increasing volume of Construction and demolition waste (CDW) associated with economic growth is posing challenges to the sustainable management of the built environment. The largest fraction of... Show moreThe increasing volume of Construction and demolition waste (CDW) associated with economic growth is posing challenges to the sustainable management of the built environment. The largest fraction of all the CDW generated in the member states of the European Union (EU) is End-of-life (EOL) concrete. The most widely applied method for EOL concrete recovery in Europe is road base backfilling, which is considered low-grade recovery. The common practice for high-grade recycling is wet process that processes and washes EOL concrete into clean coarse aggregate for concrete manufacturing. It is costly. As a result, a series of EU projects have been launched to advance the technologies for high value-added concrete recycling. A critical environmental and economic evaluation of such technological innovations is important to inform decision making, while there has been a lack of studies in this field. Hence the present study aimed to assess the efficiency of the technical innovations in high-grade concrete recycling, using an improved eco-efficiency analytical approach by integrating life cycle assessment (LCA) and life cycle costing (LCC). Four systems of high-grade concrete recycling were analyzed for comparison: (i) business-as-usual (BAU) stationary wet processing; (ii) stationary advanced dry recovery (ADR); (iii) mobile ADR; (iv) mobile ADR and Heating Air Classification (A&H). An overarching framework was proposed for LCA/LCC-type eco-efficiency assessment conforming to ISO standards. The study found that technological routes that recycle on-site and produce high-value secondary products are most advantageous. Accordingly, policy recommendations are proposed to support the technological innovations of CDW management. Show less
Sustainability challenges raised by built environment development are two-folds: on the inflow side these include resource depletion and emission problems due to material production (pre-use); on... Show moreSustainability challenges raised by built environment development are two-folds: on the inflow side these include resource depletion and emission problems due to material production (pre-use); on the outflow side they include problems of construction and demolition waste (after-use). Understanding how the future construction inflow and demolition outflow will develop is essential for early recognition of these problems. A traditional approach is through extrapolation, which is risky because changes of trends may occur. A Dynamic Material Flow Analysis approach, based on the Law of Mass Preservation, provides a better framework for long-term projection. The challenge is to understand the dynamics of the built environment stocks. It is especially true for the emerging countries, where the combined influences of rapid economic development and urbanization have to be considered but are yet rarely investigated. This thesis develops the currently available approaches by including general socio-economic and specific urbanization-driven factors in China. Case studies on Chinese housing stock dynamics indicate: demolition activities in Chinese cities will continue to grow throughout the rest of the 21st century; a shrinking demand for residential steel may be expected over the next few decades, which may lead to a decrease in global steel consumption of up to 10%. Show less
Hu, M.; Bergsdal, H.; Voet, E. van der; Huppes, G.; Muller, D.B. 2010
