What are the energy and greenhouse gas benefits of repurposing non-residential buildings into apartments?

This study examines the potential strategies for reducing embodied energy and greenhouse gas emissions through adaptive reuse of non-residential buildings for residential purposes, as compared to new construction of apartment buildings. Such an approach can address housing crises in urban areas with an abundance of underutilized non-residential buildings, promoting sustainable housing growth. A comprehensive assessment of repurposing in California reveals approximately 510 million m² of floor space across 230,000 non-residential buildings in the current building stock. The potential reduction in embodied energy and CO2eq emissions ranges from 0.14 to 1.4 billion GJ and 5.0–70 million metric tons for the state, respectively, contingent upon the percentage of repurposed floor space (10–100%) and adaptive reuse scenario (retaining structural components and façade or solely the structure). A repurposed building avoids about 56% of embodied energy, 34-48% of CO2 eq emissions, and 72% of materials by mass compared to building a new apartment building. However, various technical, financial, and regulatory challenges may hinder emissions reductions, necessitating proactive policy measures. Cities can potentially expedite the process by streamlining approvals for mixed-use adaptive reuse projects involving both commercial and residential spaces

Salt slag recycled by-products in high insulation geopolymer cellular concrete manufacturing

[EN] This investigation presents an important contribution to the understanding of the ¿zero discharge in the aluminium cycle¿ goal. The salt slag recycled by-product was reused as alternative aerating agent in the manufacture of cellular concretes: fluid catalytic cracking catalyst (FCC) ¿ based geopolymer (GCC) and blast furnace (BFS) ¿ based alkali-activated (AACC). The hydrogen emission test was used to evaluate the gas releasing properties because of the presence of metallic aluminium in the salt slag. Density (kg/cm3), compressive strength (MPa) and thermal conductivity (W/mK) for GCC were 75, 6.9 and 0.31 and for AACC were 602, 7.5 and 0.16.The authors give special grateful to Befesa Aluminio S.L (Valladolid, Spain) for the granulated paval supply. The authors would also thanks to Cementval and BPOil for precursors supplying. Thanks are given to the Electron Microscopy Service of the Universitat Politècnica de València (Spain).Font-Pérez, A.; Soriano Martinez, L.; Monzó Balbuena, JM.; Moraes, J.; Borrachero Rosado, MV.; Paya Bernabeu, JJ. (2020). Salt slag recycled by-products in high insulation geopolymer cellular concrete manufacturing. Construction and Building Materials. 231:1-13. https://doi.org/10.1016/j.conbuildmat.2019.117114S113231Meyer, C. (2009). The greening of the concrete industry. Cement and Concrete Composites, 31(8), 601-605. doi:10.1016/j.cemconcomp.2008.12.010Petek Gursel, A., Masanet, E., Horvath, A., & Stadel, A. (2014). Life-cycle inventory analysis of concrete production: A critical review. Cement and Concrete Composites, 51, 38-48. doi:10.1016/j.cemconcomp.2014.03.005Panesar, D. K. (2013). Cellular concrete properties and the effect of synthetic and protein foaming agents. Construction and Building Materials, 44, 575-584. doi:10.1016/j.conbuildmat.2013.03.024B. Dolton, C. Hannah, Cellular Concrete : Engineering and Technological Advancement for Construction in Cold Climates, (2006) 1–11.Narayanan, N., & Ramamurthy, K. (2000). Structure and properties of aerated concrete: a review. Cement and Concrete Composites, 22(5), 321-329. doi:10.1016/s0958-9465(00)00016-0Holt, E., & Raivio, P. (2005). Use of gasification residues in aerated autoclaved concrete. Cement and Concrete Research, 35(4), 796-802. doi:10.1016/j.cemconres.2004.05.005Mo, K. H., Alengaram, U. J., Jumaat, M. Z., Yap, S. P., & Lee, S. C. (2016). Green concrete partially comprised of farming waste residues: a review. Journal of Cleaner Production, 117, 122-138. doi:10.1016/j.jclepro.2016.01.022Luukkonen, T., Abdollahnejad, Z., Yliniemi, J., Kinnunen, P., & Illikainen, M. (2018). One-part alkali-activated materials: A review. Cement and Concrete Research, 103, 21-34. doi:10.1016/j.cemconres.2017.10.001Duxson, P., Provis, J. L., Lukey, G. C., & van Deventer, J. S. J. (2007). The role of inorganic polymer technology in the development of ‘green concrete’. Cement and Concrete Research, 37(12), 1590-1597. doi:10.1016/j.cemconres.2007.08.018Ducman, V., & Korat, L. (2016). Characterization of geopolymer fly-ash based foams obtained with the addition of Al powder or H2O2 as foaming agents. Materials Characterization, 113, 207-213. doi:10.1016/j.matchar.2016.01.019Esmaily, H., & Nuranian, H. (2012). Non-autoclaved high strength cellular concrete from alkali activated slag. Construction and Building Materials, 26(1), 200-206. doi:10.1016/j.conbuildmat.2011.06.010Font, A., Borrachero, M. V., Soriano, L., Monzó, J., & Payá, J. (2017). Geopolymer eco-cellular concrete (GECC) based on fluid catalytic cracking catalyst residue (FCC) with addition of recycled aluminium foil powder. Journal of Cleaner Production, 168, 1120-1131. doi:10.1016/j.jclepro.2017.09.110Font, A., Borrachero, M. V., Soriano, L., Monzó, J., Mellado, A., & Payá, J. (2018). New eco-cellular concretes: sustainable and energy-efficient materials. Green Chemistry, 20(20), 4684-4694. doi:10.1039/c8gc02066cArellano Aguilar, R., Burciaga Díaz, O., & Escalante García, J. I. (2010). Lightweight concretes of activated metakaolin-fly ash binders, with blast furnace slag aggregates. Construction and Building Materials, 24(7), 1166-1175. doi:10.1016/j.conbuildmat.2009.12.024RLG International cementreview, (n.d.).World Aluminium, Environmental Metrics Report Year 2010 Data Final, (2014) 21.Hong, S.-H., Lee, D.-W., & Kim, B.-K. (2000). Manufacturing of aluminum flake powder from foil scrap by dry ball milling process. Journal of Materials Processing Technology, 100(1-3), 105-109. doi:10.1016/s0924-0136(99)00469-0A. Al Ashraf, Energy Consumption and the CO2 footprint in aluminium production, (2014).Befesa :: Press :: News archive :: 2013, (n.d.). http://www.befesa.es/web/en/prensa/historico_de_noticias/2013/bma_20130307.html (accessed April 15, 2018).Araújo, E. G. de, & Tenório, J. A. S. (2005). Cellular Concrete with Addition of Aluminum Recycled Foil Powders. Materials Science Forum, 498-499, 198-204. doi:10.4028/www.scientific.net/msf.498-499.198Song, Y., Li, B., Yang, E.-H., Liu, Y., & Ding, T. (2015). Feasibility study on utilization of municipal solid waste incineration bottom ash as aerating agent for the production of autoclaved aerated concrete. Cement and Concrete Composites, 56, 51-58. doi:10.1016/j.cemconcomp.2014.11.006Moraes, J. C. B., Tashima, M. M., Akasaki, J. L., Melges, J. L. P., Monzó, J., Borrachero, M. V., … Payá, J. (2016). Increasing the sustainability of alkali-activated binders: The use of sugar cane straw ash (SCSA). Construction and Building Materials, 124, 148-154. doi:10.1016/j.conbuildmat.2016.07.090N.E. En, N. Une-en, española, (2005).F. Babbitt, R.E. Barnett, M.L. Cornelius, B.T. Dye, D.L. Liotti, S.B. Schmidt, J.E. Tanner, S.C. Valentini, ACI 523.3R-14 Guide for Cellular Concretes above 50 lb/ft3 (800 kg/m3), 2014.ASTM International, ASTM D5334 – 14 Standard Test Method for Determination of Thermal Conductivity of Soil and Soft Rock by Thermal Needle Probe Procedure, (n.d.).IEEE 442-1981 – IEEE Guide for Soil Thermal Resistivity Measurements, (n.d.).D.R. van Boggelen, Safe aluminium dosing in AAC plants, 5th Int. Conf. Autoclaved Aerated Concr. (2011) 45–50.Porciúncula, C. B., Marcilio, N. R., Tessaro, I. C., & Gerchmann, M. (2012). Production of hydrogen in the reaction between aluminum and water in the presence of NaOH and KOH. Brazilian Journal of Chemical Engineering, 29(2), 337-348. doi:10.1590/s0104-66322012000200014Aleksandrov, Y. A., Tsyganova, E. I., & Pisarev, A. L. (2003). Russian Journal of General Chemistry, 73(5), 689-694. doi:10.1023/a:1026114331597Yang, K.-H., Lee, K.-H., Song, J.-K., & Gong, M.-H. (2014). Properties and sustainability of alkali-activated slag foamed concrete. Journal of Cleaner Production, 68, 226-233. doi:10.1016/j.jclepro.2013.12.068Sanjayan, J. G., Nazari, A., Chen, L., & Nguyen, G. H. (2015). Physical and mechanical properties of lightweight aerated geopolymer. Construction and Building Materials, 79, 236-244. doi:10.1016/j.conbuildmat.2015.01.043Nambiar, E. K. K., & Ramamurthy, K. (2007). Air‐void characterisation of foam concrete. Cement and Concrete Research, 37(2), 221-230. doi:10.1016/j.cemconres.2006.10.009Narayanan, N., & Ramamurthy, K. (2000). Microstructural investigations on aerated concrete. Cement and Concrete Research, 30(3), 457-464. doi:10.1016/s0008-8846(00)00199-xAlexanderson, J. (1979). Relations between structure and mechanical properties of autoclaved aerated concrete. Cement and Concrete Research, 9(4), 507-514. doi:10.1016/0008-8846(79)90049-

Life-Cycle Assessment of Concrete: Decision-Support Tool and Case Study Application

Globally, construction and operation of the built environment is recognized as a significant source of greenhouse gas emissions (GHG). About 40% of anthropogenic GHG and 40% of raw materials use are assigned to buildings. Concrete, the most widely used man-made material, is used in buildings because of its flexibility and adaptability, its low maintenance requirements during the service life of the structures, and the economic and widespread accessibility of its constituents. The substantial production and consumption of global concrete manufacturing accounts for more than five percent of the human-related carbon dioxide emissions annually, mostly attributable to the production of cement clinker. However, environmental impacts are not limited to only GHG emissions. The analysis and quantification of the overall environmental impacts of concrete manufacturing and its application in building projects requires a holistic approach that is known as life-cycle assessment (LCA). In this dissertation, a new process-based LCA tool (GreenConcrete LCA) was developed for the purpose of evaluating the environmental impacts of concrete from extraction of its raw materials to the end-of-life stage. The GreenConcrete LCA has MS Excel and web versions, both of which have the capability of calculating and comparing the LCA of different concrete mixtures designed for specific project purposes. In the tool, not only the direct but also the supply-chain impacts of manufacturing processes of concrete and its materials are evaluated. The integration of regional variations and technological alternatives within the tool offers a wide range of applicability and flexibility for users in the U.S. and worldwide. The new tool will ultimately allow policy makers, researchers, architects, civil engineers, and government agencies to assess the environmental sustainability of concrete in various building construction projects. With the help of the tool, sensitivity analysis was conducted. GWP reduced significantly with the replacement of ordinary portland cement with supplementary cementitious materials (SCMs) such as fly ash and slag in concrete. Additionally, it was shown that environmentally and structurally advantageous concrete mixtures could be made with high-volumes of fly ash and limestone. A wide range of early and long term strengths were attainable depending on the selected mixture proportion. GHG emissions and criteria air pollutants were also successfully reduced and were in all cases similar to or lower than for ordinary portland cement concrete.The concrete and steel frame versions of a dormitory building in Istanbul were also analyzed. Results from the case study showed that the operation phase dominated in GWP and energy consumption, which is consistent with literature results. Finally, Turkish cement and concrete sector case study scenario analysis show that reductions in CO2-eq emissions can be achieved through, strategic choice of locations for cement and concrete plants for local and international distribution of products by less carbon-intensive modes of transportation, i.e., rail and water; switching to lower-carbon fuels in cement kilns, and expanding the use of biofuels and electric vehicles in delivery of cement and concrete products; Improvements in energy efficiency by installation of existing best available technologies for new plants and replacing older technologies for existing plants, switching to less carbon-intensive energy sources for electricity generation, integration of waste heat recovery systems in cement plants for off-grid electricity generation and using more energy efficient equipment in cement and concrete plants, use of alternative raw materials as sustainable waste management and GHG emission reduction options. Although these strategies can have great potential to abate CO2-eq emissions in cement and concrete industry both in Turkey and globally, technical, regulatory, and economic challenges are still considered obstacles against implementation of new approaches

Life-Cycle Assessment of High-Strength Concrete Mixtures with Copper Slag as Sand Replacement

Aggregate consumption rates have now exceeded natural renewal rates, signaling shortages both locally and globally. Even more concerning is that the worldwide markets for construction aggregates are projected to grow at an annual rate of 5.2% in the near future. This increase is attributed to rapid population growth coupled with the economic development worldwide. In terms of material availability, one of the most vulnerable regions is the Asia-Pacific region specifically, Singapore, where there is higher demand but limited availability of natural sand and gravel for use as aggregates in concrete construction projects. This paper focuses mainly on the environmental impacts of fine aggregate alternatives used in high-strength concrete applications in Singapore, which is one of the major global importers of natural sand following China. Singapore has been experiencing political and environmental challenges linked to the shortage of natural sand use as aggregates, even while the demand is increasing in the construction sector. Copper slag, a readily available waste material from shipyards in Singapore, is a possible replacement material for a portion of the natural sand in concrete mixtures, thus sustaining the projected growth in the region. A life-cycle assessment approach is applied to investigate the environmental impacts of copper slag and its alternative use as natural sand in high-strength concrete applications in Singapore. The system boundary consists of the major production processes of concrete constituents (including Portland cement and fine and coarse aggregates, with CS considered as fine aggregate) from a cradle-to-gate perspective, consisting of relevant life-cycle phases of raw materials extraction, transportation, and production processes at the relevant facility where the production occurs. Output from the assessment is provided in terms of embodied energy use and air emissions of concrete mixes with varying percentages of copper slag as fine aggregate. Results show that environmental impacts of aggregates decrease with the increasing substitution rate of natural sand with copper slag when calculated on the basis per unit volume of the concrete mix. For example, 40% and 100% sand replacements with copper slag result in a reduction of 8% and 40% in embodied energy, 12% and 30% in global warming potential, 8% and 41% in acidification, and 7% and 35% in particulate matter formation, respectively. Normalized impacts (i.e., normalized with respect to compressive strength) are observed to remain at almost similar levels for concrete mixes with up to 40% natural sand having been replaced with copper slag. Therefore, it is recommended that replacement of fine aggregates by 40–50% of copper slag (by weight) will produce concrete mixtures with comparable environmental impacts while maintaining feasible durability and strength properties

Life‐Cycle Greenhouse Gas Emissions of Electricity Generation and Storage Technologies and Common Residential, Commercial, Industrial, and Agricultural Building Technologies

We have conducted a study to review and synthesize the current state of data availability for cradle-to-grave life-cycle emissions from major building technologies and electricity generation and storage technologies as specific to California as could be found. Results from 280 building technologies (120 unique) were organized across 9 categories and 27 subcategories. Many of the technologies in the list are common building materials, appliances, and process equipment used in the construction and operation of agricultural, residential, commercial, and industrial buildings. Target electricity generation technologies covered the GHG emissions from natural gas, solar, wind, geothermal, biomass and storage technologies for the California context. The search for relevant environmental impact data was in the form of Environmental Product Declarations (EPD) (if available), peer-reviewed journal articles, and publicly available reports from government and industry for each technology. In general, the “Building Materials” category in the building technologies area and “Wind Turbines” in the electricity generation and storage area have the most current and relevant data for California. However, we have identified several data gaps in our survey of the remaining categories. Due to lack of relevant data for California in building systems, there is an urgent need for policy makers and industry stakeholders to replicate policies such as AB 2446 to expand the coverage of availability of EPDs for products. Similarly, to achieve the SB 350 (Clean Energy and Pollution Reduction Act) goals and to support the state’s efforts to reduce GHG emissions by 80% below 1990 levels by the year 2050, we need to account for embodied emissions together with the other important life-cycle stages of renewable energy sources

Embodied energy and greenhouse gas emission trends from major construction materials of U.S. office buildings constructed after the mid-1940s

While recognized as important, calculation of embodied energy and greenhouse gas (GHG) emissions associated with buildings, especially at a large scale, has scant literature. A model has been created for estimating the inventory of structural and non-structural materials and building components and their associated embodied energy and GHG emissions for the approximately 807,400 office buildings constructed in the United States between 1946 and 2018. The buildings were modeled using eight prototypical designs. We estimate that 1100–1300 million metric tons of materials are embodied in these 807,000 buildings (90% of which have just 1–3 floors), as well as 6–7 years' worth of national construction and demolition waste. In total, 6.5 billion Gigajoules of primary energy use (∼6% of the U.S.’s 2021 energy consumption) and 0.5 billion metric tons of carbon dioxide equivalent emissions (∼8% of the U.S.’s 2020 total GHG emissions) are estimated to be embodied in these buildings. One-floor steel and wood buildings were about equally GHG intensive from structural materials as well as combined structural and non-structural materials perspectives, while reinforced concrete (RC) buildings were 50% and 27%–47% more GHG intensive, respectively. From the all-materials-use perspective, 5-floor steel buildings were 54% more GHG intensive to construct than wood buildings, and in turn RC buildings were 68% more GHG intensive than steel buildings. Non-structural material contributions were significant. Increasing economies of scale in embodied impacts can be observed as the number of floors increases. Results constitute points of reference for those who seek to find ways of reducing the carbon footprint of buildings

Water use and electricity-for-water savings trends in three representative U.S. cities

A life-cycle assessment approach is used to analyze the energy demand and greenhouse gas emissions associated with potable water usage trends in three major cities of the United States in different regions and climates and relying on different types of raw water sources. Between 2011 and 2016, a decreasing trend in per-person water consumption is observed despite growing populations. The per-person water consumption decreased by 10% in Tucson (Arizona) and Washington, DC, and by 16% in Denver (Colorado). Leveraging certain distinctive water and electricity supply characteristics of the case study cities can provide insights into potential interventions and cross-comparison for generalizing trends. In Tucson, potable water production is the most energy intensive and electricity is produced mainly from coal. The greenhouse gas emissions of the per-person water consumption in Tucson are about five times higher compared to Denver and Washington, DC, thus water savings in Tucson should be particularly pursued. GHG emissions decreased in the period by even higher percentages than water use: 15%, 14% and 27% between 2011 and 2016 for Tucson, Washington, DC, and Denver, respectively. In 2015, just four years’ worth of forgone GHG emissions in Tucson were somewhat higher than the total GHG emissions associated with water consumption in all of Washington, DC, a city with the same population size as Tucson. Results show that cities should prioritize promotion of water savings to decrease the average per-person water consumption because it can be achieved and can compensate for increases in population. Lower greenhouse gas emissions can be attained in tandem with the local electric power industry

Reduction in urban water use leads to less wastewater and fewer emissions:analysis of three representative U.S. cities

Electricity consumption and greenhouse gas (GHG) emissions associated with wastewater flows from residential and commercial water use in three major cities of the United States are analyzed and compared for the period 2010–2018. Contributions of unit wastewater treatment processes and electricity sources to the overall emissions are considered. Tucson (Arizona), Denver (Colorado), and Washington, DC were chosen for their distinct locations, climatic conditions, raw water sources, wastewater treatment technologies, and electric power mixes. Denver experienced a 20% reduction in treated wastewater volumes per person despite a 16% increase in population. In Washington, DC, the reduction was 19%, corresponding to a 16% increase in population, and in Tucson 14% despite a population growth of 3%. The electricity intensity per volume of treated wastewater was higher in Tucson (1 kWh m ^−3 ) than in Washington, DC (0.7 kWh m ^−3 ) or Denver (0.5 kWh m ^−3 ). Tucson’s GHG emissions per person were about six times higher compared to Denver and four times higher compared to Washington, DC. Wastewater treatment facilities in Denver and Washington, DC generated a quarter to third of their electricity needs from onsite biogas and lowered their GHG emissions by offsetting purchases from the grid, including coal-generated electricity. The higher GHG emission intensity in Tucson is a reflection of coal majority in the electricity mix in the period, gradually replaced with natural gas, solar, and biogas. In 2018, the GHG reduction was 20% when the share of solar electricity increased to 14% from zero in 2016. In the analysis period, reduced wastewater volumes relative to the 2010 baseline saved Denver 44 000 MWh, Washington, DC 11 000 MWh and Tucson 7000 MWh of electricity. As a result, Washington, DC managed to forgo 21 000 metric tons of CO _2-eq and Denver 34 000 metric tons, while Tucson’s cumulative emissions increased by 22 000 metric tons of CO _2-eq . This study highlights the variability observed in water systems and the opportunities that exist with water savings to allow for wastewater generation reduction, recovering energy from onsite biogas, and using energy-efficient wastewater treatment technologies

Assessing uncertainty in building material emissions using scenario-aware Monte Carlo simulation

Global greenhouse gas emissions from the built environment remain high, driving innovative approaches to develop and adopt building materials that can mitigate some of those emissions. However, life-cycle assessment (LCA) practices still lack standardized quantitative uncertainty assessment frameworks, which are urgently needed to robustly assess mitigation efforts. Previous works emphasize the importance of accounting for the three types of uncertainties that may exist within any quantitative assessment: parameter, scenario, and model uncertainty. Herein, we develop a quantitative uncertainty assessment framework that distinguishes between different types of uncertainties and suggest how these uncertainties could be handled systematically through a scenario-aware Monte Carlo simulation (MCS). We demonstrate the framework’s decision-informing power through a case study of two multilevel ordinary Portland cement (OPC) manufacturing scenarios. The MCS utilizes a first-principles-based OPC life-cycle inventory, which mitigates some of the model uncertainty that may exist in other empirical-based cement models. Remaining uncertainties are handled by scenario specification or sampling from developed probability distribution functions. We also suggest a standardized method for fitting distributions to parameter data by enumerating through and implementing distributions based on the Kolmogorov–Smirnov test. The level of detail brought by the high-resolution parameter breakdown of the model allows for developing emission distributions for each process of OPC manufacturing. This approach highlights how specific parameters, along with scenario framing, can impact overall OPC emissions. Another key takeaway includes relating the uncertainty of each process to its contributions to total OPC emissions, which can guide LCA modelers in allocating data collection and refinement efforts to processes with the highest contribution to cumulative uncertainty. Ultimately, the aim of this work is to provide a standardized framework that can provide robust estimates of building material emissions and be readily integrated within any uncertainty assessment

Comparative analysis of magnetically activated cell sorting and ultracentrifugation methods for exosome isolation.

Mesenchymal stem cell-derived exosomes regulate cell migration, proliferation, differentiation, and synthesis of the extracellular matrix, giving great potential for the treatment of different diseases. The ultracentrifugation method is the gold standard method for exosome isolation due to the simple protocol, and high yield, but presents low purity and requires specialized equipment. Amelioration of technical optimization is required for quick and reliable confinement of exosomes to translate them to the clinic as cell therapeutics In this study, we hypothesized that magnetically activated cell sorting may provide, an effective, reliable, and rapid tool for exosome isolation when compared to ultracentrifugation. We, therefore, aimed to compare the efficiency of magnetically activated cell sorting and ultracentrifugation for human mesenchymal stem cell-derived exosome isolation from culture media by protein quantification, surface biomarker, size, number, and morphological analysis. Magnetically activated cell sorting provided a higher purity and amount of exosomes that carry visible magnetic beads when compared to ultracentrifugation. The particle number of the magnetically activated cell sorting group was higher than the ultracentrifugation. In conclusion, magnetically activated cell sorting presents a quick, and reliable method to collect and present human mesenchymal stem cell exosomes to clinics at high purity for potential cellular therapeutic approaches. The novel isolation and purification method may be extended to different clinical protocols using different autogenic or allogeneic cell sources