Energy Catalyst 3103-9952 Caravel Press 10.61552/EC.2025.001 2025.001 Assessing the Energy-Saving Potential of Passive Strategies in Commercial Buildings in the Top Upcoming Megacities SumanSwathi https://orcid.org/0000-0001-7046-3308 CalautitJohn Kaiser https://orcid.org/0000-0002-1053-1652 WeiShuangyu https://orcid.org/0000-0003-0123-248X TienPaige Wenbin https://orcid.org/0000-0001-7710-3129 ChenXiangjie https://orcid.org/0000-0003-4518-9989 WangZhe https://orcid.org/0000-0002-9257-986X SunHao Hao.Sun1@nottingham.ac.uk Department of Architecture and Built Environment, University of Nottingham, Nottingham, NG7 2RD, United Kingdom Welsh School of Architecture, Cardiff University, Cardiff, CF10 3NB, United Kingdom Department of Architecture and Built Environment, University of Nottingham, Nottingham, NG7 2RD, United Kingdom; The College of Built Environment, Birmingham City University, Birmingham, B5 5JU, United Kingdom Centre for Renewable Energy Systems Technology, Loughborough University, Loughborough, LE11 3TU, United Kingdom 19042025 1 1 21 3 February 2025 11 March 2025 19 April 2025 © 2025 The Author(s). Published by Caravel Press. 2025 This is an open access article under the CC BY 4.0 licence.

Buildings account for up to 50% of energy consumption in many regions. Heating, ventilation and air-conditioning systems consume half of that energy. Passive cooling strategies can significantly reduce energy use and associated carbon emissions, especially in high-density regions like megacities. This work aims to quantify the energy-saving potential of passive strategies in five upcoming megacities, namely Hyderabad, Bogota, Johannesburg, Bangkok and Chengdu. It assesses the potential of three strategies - natural ventilation, shading and use of appropriate materials. The aspects of energy use, thermal comfort and indoor air quality are combined to identify the strategy and the city with the most energy-saving potential. The study showed that climate and occupancy hours dictated the success of each strategy in each city. The analysis and data presented here can provide guidelines for designing new buildings and retrofitting existing ones before the upcoming population surge.

 Building energy simulation Cooling Passive strategies Megacities Natural ventilation B. Keeley and C. Little, The State of the Worlds Children 2017: Children in a Digital World. ERIC, 2017. U. UN, ‘Department of economic and social affairs’, Population Division, 2017. A. Demirbas, ‘Global Renewable Energy Projections’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 4, no. 2, pp. 212–224, Oct. 2009, doi: 10.1080/15567240701620499. 10.1080/15567240701620499 L. Yang, H. Yan, and J. C. Lam, ‘Thermal comfort and building energy consumption implications–a review’, Applied energy, vol. 115, pp. 164–173, 2014. A. Aldawoud, T. Salameh, and Y. Ki Kim, ‘Double skin façade: energy performance in the United Arab Emirates’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 16, no. 5, pp. 387–405, May 2021, doi: 10.1080/15567249.2020.1813845. 10.1080/15567249.2020.1813845 X. Cao, X. Dai, and J. Liu, ‘Building energy- consumption status worldwide and the state-of- the-art technologies for zero-energy buildings during the past decade’, Energy and Buildings, vol. 128, pp. 198–213, Sep. 2016, doi: 10.1016/j.enbuild.2016.06.089. 10.1016/j.enbuild.2016.06.089 Z. Liu, ‘What is the future of solar energy? Economic and policy barriers’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 13, no. 3, pp. 169–172, Mar. 2018, doi: 10.1080/15567249.2017.1416704. 10.1080/15567249.2017.1416704 S. Shukla and H. Zia, ‘Energy efficiency in India: Policies and their impacts’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 11, no. 10, pp. 982–989, 2016. R. Ohlan, ‘Renewable and nonrenewable energy consumption and economic growth in India’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 11, no. 11, pp. 1050–1054, Nov. 2016, doi: 10.1080/15567249.2016.1190801. 10.1080/15567249.2016.1190801 V. Stavrakas and A. Flamos, ‘A modular high- resolution demand-side management model to quantify benefits of demand-flexibility in the residential sector’, Energy Conversion and Management, vol. 205, p. 112339, 2020. Y. Chen, Z. Tong, and A. Malkawi, ‘Investigating natural ventilation potentials across the globe: Regional and climatic variations’, Building and Environment, vol. 122, pp. 386–396, Sep. 2017, doi: 10.1016/j.buildenv.2017.06.026. 10.1016/j.buildenv.2017.06.026 S. Attia, J. L. M. Hensen, L. Beltrán, and A. De Herde, ‘Selection criteria for building performance simulation tools: contrasting architects’ and engineers’ needs’, Journal of Building Performance Simulation, vol. 5, no. 3, pp. 155–169, May 2012, doi: 10.1080/19401493.2010.549573. 10.1080/19401493.2010.549573 G. Shady, ‘Early design simulation tools for net zero energy buildings: A comparison of ten tools’, presented at the Proceedings of Building Simulation 2011: 12th Conference of International Building Performance Simulation Association, Sydney, 11 月, 2011, pp. 94–101. T. Reeves, S. Olbina, and R. Issa, ‘Guidelines for using Building Information Modeling (BIM) for environmental analysis of high-performance buildings’, in Computing in Civil Engineering (2012), 2012, pp. 277–284. S. Bilgen and İ. Sarıkaya, ‘Energy conservation policy and environment for a clean and sustainable energy future’, Energy Sources, Part B: Economics, Planning, and Policy, vol. 13, no. 3, pp. 183–189, Mar. 2018, doi: 10.1080/15567249.2017.1423412. 10.1080/15567249.2017.1423412 R. J. de Dear and G. S. Brager, ‘Thermal comfort in naturally ventilated buildings: revisions to ASHRAE Standard 55’, Energy and Buildings, vol. 34, no. 6, pp. 549–561, Jul. 2002, doi: 10.1016/S0378-7788(02)00005-1. 10.1016/S0378-7788(02)00005-1 I. Oropeza-Perez and P. A. Østergaard, ‘Potential of natural ventilation in temperate countries – A case study of Denmark’, Applied Energy, vol. 114, pp. 520–530, Feb. 2014, doi: 10.1016/j.apenergy.2013.10.008. 10.1016/j.apenergy.2013.10.008 I. Oropeza-Perez and P. A. Østergaard, ‘Energy saving potential of utilizing natural ventilation under warm conditions – A case study of Mexico’, Applied Energy, vol. 130, pp. 20–32, Oct. 2014, doi: 10.1016/j.apenergy.2014.05.035. 10.1016/j.apenergy.2014.05.035 M. Beccali, V. Strazzeri, M. L. Germanà, V. Melluso, and A. Galatioto, ‘Vernacular and bioclimatic architecture and indoor thermal comfort implications in hot-humid climates: An overview’, Renewable and Sustainable Energy Reviews, vol. 82, pp. 1726–1736, Feb. 2018, doi: 10.1016/j.rser.2017.06.062. 10.1016/j.rser.2017.06.062 S. P. Sivaraman, ‘Concepts from traditional Indian architecture to reduce energy consumption in modern Indian architecture’, 2017. N. Pesic, J. R. Calzada, and A. M. Alcojor, ‘Natural ventilation potential of the Mediterranean coastal region of Catalonia’, Energy and Buildings, vol. 169, pp. 236–244, Jun. 2018, doi: 10.1016/j.enbuild.2018.03.061. 10.1016/j.enbuild.2018.03.061 M. Jantunen, J. J. Jaakkola, and M. Krzyzanowski, Assessment of exposure to indoor air pollutants, no. 78. WHO Regional Office Europe, 1997. P. MacNaughton, J. Pegues, U. Satish, S. Santanam, J. Spengler, and J. Allen, ‘Economic, environmental and health implications of enhanced ventilation in office buildings’, International journal of environmental research and public health, vol. 12, no. 11, pp. 14709– 14722, 2015. A. P. Jones, ‘Indoor air quality and health’, Atmospheric Environment, vol. 33, no. 28, pp. 4535–4564, Dec. 1999, doi: 10.1016/S1352-2310(99)00272-1. 10.1016/S1352-2310(99)00272-1 Z. Tong, R. W. Baldauf, V. Isakov, P. Deshmukh, and K. M. Zhang, ‘Roadside vegetation barrier designs to mitigate near-road air pollution impacts’, Science of the Total Environment, vol. 541, pp. 920–927, Jan. 2016, doi: 10.1016/j.scitotenv.2015.09.067. 10.1016/j.scitotenv.2015.09.067 T. Ben-David and M. S. Waring, ‘Impact of natural versus mechanical ventilation on simulated indoor air quality and energy consumption in offices in fourteen U.S. cities’, Building and Environment, vol. 104, pp. 320–336, Aug. 2016, doi: 10.1016/j.buildenv.2016.05.007. 10.1016/j.buildenv.2016.05.007 R. Wookey, A. Bone, C. Carmichael, and A. Crossley, ‘Minimum home temperature thresholds for health in winter–a systematic literature review’, Public Health England, London, 2014. N. A. Al-Tamimi and S. F. S. Fadzil, ‘The Potential of Shading Devices for Temperature Reduction in High-Rise Residential Buildings in the Tropics’, Procedia Engineering, vol. 21, pp. 273–282, 2011, doi: https://doi.org/10.1016/j.proeng.2011.11.2015. 10.1016/j.proeng.2011.11.2015 S. Shahzad, K. Calautit, S. Wei, P. W. Tien, J. Calautit, and B. Hughes, ‘Analysis of the thermal comfort and energy performance of a thermal chair for open plan office’, Journal of Sustainable Development of Energy, Water and Environment Systems, vol. 8, no. 2, pp. 373–395, 2020. S. Shahzad, J. K. Calautit, K. Calautit, B. Hughes, and A. I. Aquino, ‘Advanced personal comfort system (APCS) for the workplace: A review and case study’, Energy and Buildings, vol. 173, pp. 689–709, Aug. 2018, doi: 10.1016/j.enbuild.2018.02.008. 10.1016/j.enbuild.2018.02.008 IES. (2024). ApacheSim calculation methods: Virtual environment 6.3. Integrated Environmental Solutions Limited. [Accessed: 03.12.]; Available from Https://www. iesve.com/downloads/help/Thermal/Reference/ ApacheSimCalculationMethods. pdf. A. D’Amico, G. Ciulla, D. Panno, and S. Ferrari, ‘Building energy demand assessment through heating degree days: The importance of a climatic dataset’, Applied Energy, vol. 242, pp. 1285–1306, May 2019, doi: 10.1016/j.apenergy.2019.03.167. 10.1016/j.apenergy.2019.03.167 United States Department of Energy (DOE), ‘Weather Data’. [Online]. Available: https://energyplus.net/weather The CIBSE Energy Performance Group, ‘Charted Institute of Building Services Engineers, CIBSE. 2012. “Carbon Bites: From the CIBSE Energy Performance Group.”’ [Online]. Available: https://www.cibse.org/getmedia/55cf31bd-d9eb-4ffa-b2e2-e567327ee45f/cb11.pdf.aspx. C. L. Cheng, C. L. Chen, C. P. Chou, and C. Y. Chan, ‘A mini-scale modeling approach to natural daylight utilization in building design’, Building and Environment, vol. 42, no. 1, pp. 372–384, Jan. 2007, doi: 10.1016/j.buildenv.2005.08.004. 10.1016/j.buildenv.2005.08.004 J.-F. Bastin et al., ‘Understanding climate change from a global analysis of city analogues’, PLOS ONE, vol. 14, no. 7, p. e0217592, Jul. 2019, doi: 10.1371/journal.pone.0217592. 10.1371/journal.pone.0217592 Integrated Environmental Solutions Ltd, ‘MacroFlo Opening Types User Guide - Virtual Environment 6.0.’ [Online]. Available: https://www.iesve.com/downloads/help/Ther mal/MacroFloOpeningTypes.pdf Y.-W. Lim, M. Z. Kandar, M. H. Ahmad, D. R. Ossen, and A. M. Abdullah, ‘Building façade design for daylighting quality in typical government office building’, Building and Environment, vol. 57, pp. 194–204, Nov. 2012, doi: 10.1016/j.buildenv.2012.04.015. 10.1016/j.buildenv.2012.04.015 R. S. Briggs, R. G. Lucas, and Z. T. Taylor, ‘Climate classification for building energy codes and standards: Part 1-development process’, ASHRAE Transactions, vol. 109, p. 109, 2003. R. S. Briggs, R. G. Lucas, and Z. T. Taylor, ‘Climate classification for building energy codes and standards: Part 2-zone definitions, maps, and comparisons’, ASHRAE Transactions, vol. 109, p. 122, 2003. A. A. S. Bahdad, S. F. S. Fadzil, H. O. Onubi, and S. A. BenLasod, ‘Sensitivity analysis linked to multi- objective optimization for adjustments of light- shelves design parameters in response to visual comfort and thermal energy performance’, Journal of Building Engineering, vol. 44, p. 102996, Dec. 2021, doi: 10.1016/j.jobe.2021.102996. 10.1016/j.jobe.2021.102996 A. Toutou, M. Fikry, and W. Mohamed, ‘The parametric based optimization framework daylighting and energy performance in residential buildings in hot arid zone’, Alexandria engineering journal, vol. 57, no. 4, pp. 3595–3608, 2018. K. Lakhdari, L. Sriti, and B. Painter, ‘Parametric optimization of daylight, thermal and energy performance of middle school classrooms, case of hot and dry regions’, Building and Environment, vol. 204, p. 108173, Oct. 2021, doi: 10.1016/j.buildenv.2021.108173. 10.1016/j.buildenv.2021.108173 C. Carletti, F. Sciurpi, and L. Pierangioli, ‘The Energy Upgrading of Existing Buildings: Window and Shading Device Typologies for Energy Efficiency Refurbishment’, Sustainability, vol. 6, no. 8, pp. 5354–5377, 2014, doi: 10.3390/su6085354. 10.3390/su6085354 M. J. Crosbie, The passive solar design and construction handbook. John Wiley & Sons, 1998. International Energy Council, ‘IECC International Energy Council Code. 2009. “International Energy Council Code 2009”’. [Online]. Available: https://www.lightingdesignlab.com/sites/defa ult/files/pdf/International%20Energy%20Cons ervation%20Code_IECC_2009.pdf. NOAA, ‘Earth System Research Laboratory: Global Monitoring Division, “Trends in Atmospheric Carbon Dioxide”’. [Online]. Available: https://www.esrl.noaa.gov/gmd/ccgg/trends/g lobal.html KnowledgeMiner Software, ‘Prediction of CO2 Concentration till 2030’. [Online]. Available: http://www.climateprediction.eu/cc/Main/Ent ries/2011/6/27_Prediction_of_CO2_Concentrati on_till_2030.html Statista, ‘Number of passenger cars and commercial vehicles in use worldwide from 2006 to 2015’. [Online]. Available: https://www.statista.com/statistics/281134/n umber-of-vehicles-in-use-worldwide/