Document Type : Original Article
Authors
1 UET PESHAWAR
2 Department of Engineering, University of Palermo, Viale Delle Scienze, Building 9, 90133 Palermo, Italy
Abstract
Net-Zero Energy Buildings (NZEBs) designed for present climatic conditions face a dual mid-century challenge: rising cooling demand increases electricity consumption, while climate-related photovoltaic (PV) losses reduce on-site generation. This study introduces the Net-Zero Divergence Factor (DF), a normalized, additive metric quantifying the combined erosion of net-zero performance over time. The framework is applied to a 511 m² office building in Karachi, Pakistan, from 2025 to 2050 under the HadCM3 A2 scenario. Climate-adjusted weather files are generated using CCWorldWeatherGen, building loads simulated in EnergyPlus v25.2, and PV generation modelled in PVSyst v7.4.7. Mid-century climate drift erodes 5.13% ± 1.50% of baseline annual load, comprising a 10.02% increase in cooling electricity (demand pressure: +2.58%) and a 2.45% reduction in PV generation (supply pressure: +2.55%). At the simulated thermal-loss coefficient (Uc = 20 W/m²K), the annual balance changes from a 3,266 kWh surplus in 2025 to a 778 kWh deficit in 2050 (DF = −0.99% ± 1.50%). Across Uc = 15–20 W/m²K, the mounting-dependent divergence ranges from −0.99% to −4.59%, while a propagated flush-mounted-plus-urban-heat-island case reaches −5.25%. Seasonal DF ranges from −29.60% in summer to +29.93% in winter, and grid-dependent operation increases from four to five months. These seasonal patterns are pronounced, although season-specific uncertainty was not propagated. The study demonstrates that annual balance alone can conceal substantial intra-annual grid dependence and supports incorporating climate-adjusted, seasonal performance indicators into NZEB design and certification. The DF is scenario-agnostic; CMIP6 SSP validation remains a priority for wider application and validation.
Keywords
Main Subjects
[1] UNEP and Global ABC, 2024 Global Status Report for Buildings and Construction, United Nations Environment Programme, Nairobi, 2024. https://www.unep.org/resources/report/global-status-report-buildings-and-construction-20242025
[2] IEA, “Buildings — Energy System,” International Energy Agency, Paris, 2023. https://www.iea.org/energy-system/buildings
[3] C. Maduta, D. D’Agostino, S. Tsemekidi-Tzeinaraki, and L. Castellazzi, “From Nearly Zero-Energy Buildings (NZEBs) to Zero-Emission Buildings (ZEBs): Current status and future perspectives,” Energy and Buildings, vol. 328, pp. 115133, 2025. https://doi.org/10.1016/j.enbuild.2024.115133
[4] G. Ramos Ruiz and A. Olloqui del Olmo, “Climate Change Performance of nZEB Buildings,” Buildings vol. 12 no 10 pp 1755, 2022 https://doi.org/10.3390/buildings12101755
[5] European Commission, “Energy Performance of Buildings Directive (EU) 2024/1275,” Official Journal of the European Union, 8 May 2024. https://energy.ec.europa.eu/topics/energy-efficiency/energy-performance-buildings/energy-performance-buildings-directive_en
[6] S. Chaturvedi and D. Elangovan, “Identification of climate adaptive multivariate optimization methodologies for the design of NZEB in India: a holistic review,” Frontiers in Energy Efficiency, vol. 2, pp. 1430647, 2024. https://doi.org/10.3389/fenef.2024.1430647
[7] F. Ascione, R. F. De Masi, A. Gigante, and G. P. Vanoli, “Resilience to the climate change of nearly zero energy-building designed according to the EPBD Recast,” Energy and Buildings, vol. 256, pp. 111739, 2022. https://doi.org/10.1016/j.enbuild.2022.112004
[8] X. Chen, H. Mao, N. Cheng, L. Ma, Z. Tian, Y. Luo, C. Zhou, H. Li, Q. Wang, W. Kong, and J. Fan, “Climate change impacts on global photovoltaic variability,” Applied Energy, vol. 374(C), 2024. https://doi.org/10.1016/j.apenergy.2024.124087
[9] Wu, H., Kong, Q., Huber, M., Sun, M., & Craig, M. T. (2026). Climate change will increase high-temperature risks, degradation, and costs of rooftop photovoltaics globally. Joule, 10(1), https://doi.org/10.1016/j.joule.2025.102218
[10] M. Bughio, M. S. Khan, W. A. Mahar, and T. Schuetze, “Impact of Passive Energy Efficiency Measures on Cooling Energy Demand in an Architectural Campus Building in Karachi, Pakistan,” Sustainability, vol. 13, no. 13, pp. 7251, 2021. https://doi.org/10.3390/su13137251
[11] S. Summa, L. Tarabelli, G. Ulpiani, and C. Di Perna, “Impact of Climate Change on the Energy and Comfort Performance of nZEB: A Case Study in Italy,” Climate, vol. 8, no. 11,
- 125, 2020. https://doi.org/10.3390/cli8110125
[12] R. F. De Masi and others, “Impact of weather data and climate change projections in the refurbishment design of residential buildings in cooling dominated climate,” Applied Energy, vol. 303, pp. 117591, 2021. https://doi.org/10.1016/j.apenergy.2021.117584
[13] IPCC, Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the IPCC, V. Masson-Delmotte and others, Eds., Cambridge University Press, 2021. https://doi.org/10.1017/9781009157896
[14] IPCC, Climate Change 2023: Synthesis Report, H. Lee and J. Romero, Eds., IPCC, Geneva, 2023. https://doi.org/10.59327/IPCC/AR6-9789291691647
[15] A. M. Khourchid, T. A. Al-Ansari, and S. G. Al-Ghamdi, “Cooling Energy and Climate Change Nexus in Arid Climate and the Role of Energy Transition,” Buildings, vol. 13, no. 4, pp. 836, 2023. https://doi.org/10.3390/buildings13040836
[16] Scoccimarro, E., Cattaneo, O., Gualdi, S. et al., “Country-level energy demand for cooling has increased over the past two decades,” Communications Earth & Environment, vol. 4, pp. 198, 2023. https://doi.org/10.1038/s43247-023-00878-3
[17] E. Ahmadian, C. Bingham, A. Elnokaly, B. Sodagar, and I. Verhaert, “Impact of Climate Change and Technological Innovation on the Energy Performance and Built Form of Future Cities,” Energies, vol. 15, no. 22, pp. 8592, 2022. https://doi.org/10.3390/en15228592
[18] S. E. Belcher, J. N. Hacker, and D. S. Powell, “Constructing design weather data for future climates,” Building Services Engineering Research and Technology, vol. 26, no. 1, pp. 49–61, 2005. https://doi.org/10.1191/0143624405bt112oa
[19] M. F. Jentsch, A. S. Bahaj, and P. A. B. James, “Climate change future proofing of buildings — Generation and assessment of building simulation weather files,” Energy and Buildings, vol. 40, no. 12, pp. 2148–2168, 2008. https://doi.org/10.1016/j.enbuild.2008.06.005
[20] M. Deru, K. Field, D. Studer, K. Benne, B. Griffith, P. Torcellini, and others, U.S. Department of Energy Commercial Reference Building Models of the National Building Stock, National Renewable Energy Laboratory, NREL/TP-5500-46861, 2011. https://www.researchgate.net/publication/262107107_US_Department_of_Energy_Commercial_Reference_Building_Models_of_the_National_Building_Stock
[21] C. Gordon, C. Cooper, C. A. Senior, H. Banks, J. M. Gregory, T. C. Johns, J. F. B. Mitchell, and R. A. Wood, “The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments,” Climate Dynamics, vol. 16, pp. 147–168, 2000. https://doi.org/10.1007/s003820050010
[22] ASHRAE, ANSI/ASHRAE/IESNA Standard 90.1-2004: Energy Standard for Buildings Except Low-Rise Residential Buildings, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, 2004.
[23] M. F. Jentsch, P. A. B. James, L. Bourikas, and A. S. Bahaj, “Transforming existing weather data for worldwide locations to enable energy and building performance simulation under future climates,” Renewable Energy, vol. 55, pp. 514–524, 2013. https://doi.org/10.1016/j.renene.2012.12.049
[24] P. Gonçalves and others, “Effectiveness of CCWorldWeatherGen weather file generation tool,” Ambiente Construído, 2024. https://doi.org/10.1590/s1678-86212024000100771
[25] Mohamed Imam, Yu Chen and Tyrone Marshall, “Integrating Climate Change Projections in Building Performance Simulations: Case Study of 17 North American Cities,” Journal of Architectural Engineering, vol. 29, no. 3, 2023. https://doi.org/10.1061/JAEIED.AEENG-1593
[26] H. van Dijk and others, “The new EN ISO 52000 family of standards to assess the energy performance of buildings put in practice,” REHVA Journal, 2019.
[27] Mashaly, A., Elmadawy, M., Elgohary, M. et al. “Novel and cost-efficient design of stand-alone PV system with simulation using PVsyst and experimental validation,” Scientific Reports, vol. 15, pp. 1–17, 2025. https://doi.org/10.1038/s41598-025-28401-y
[28] S. Bentouba, M. Bourouis, N. Zioui, A. Pirashanthan, and D. Velauthapillai, “Performance assessment of a 20 MW photovoltaic power plant in a hot climate using real data and simulation tools,” Energy Reports, vol. 7, pp. 8087–8099, 2021. https://doi.org/10.1016/j.egyr.2021.10.082
[29] M. W. Anwar, Z. Ali, A. Javed, and others, “Analysis of the effect of passive measures on the energy consumption and zero-energy prospects of residential buildings in Pakistan,” Building Simulation, vol. 14, pp. 1325–1342, 2021. https://doi.org/10.1007/s12273-020-0729-8
[30] X. Hou, M. Wild, D. Folini, S. Kazadzis, and J. Wohland, “Climate change impacts on solar power generation and its spatial variability in Europe based on CMIP6,” Earth System Dynamics, vol. 12, no. 4, pp. 1099–1113, 2021. https://doi.org/10.5194/esd-12-1099-2021
[31] D. Yadav, S. Khatoon, J. Singh, and R. B. Singh, “Experimental analysis of elevated tem-perature and soiling loss on rooftop PV modules performance under composite climatic conditions,” Scientific Reports, vol. 15, pp. 16622, 2025. https://doi.org/10.1038/s41598-025-25846-z
[32] W. S. Ebhota and P. Y. Tabakov, “Influence of photovoltaic cell technologies and elevated temperature on photovoltaic system performance,” Ain Shams Engineering Journal, vol. 14, no. 7, pp. 101984, 2023. https://doi.org/10.1016/j.asej.2022.101984
[33] Zakari Y, Vuille F and Lehning M, “Climate Change Impact Assessment for Future Wind and Solar Energy Installations in India,” Frontiers in Energy Research, vol. 10, pp. 859321, 2022. https://doi.org/10.3389/fenrg.2022.859321
[34] Olusola Bamisile, Caroline Acen, Dongsheng Cai, “The environmental factors affecting solar photovoltaic output,” Renewable and Sustainable Energy Reviews, vol. 204, pp. 114793, 2024. https://doi.org/10.1016/j.rser.2024.115073
[35] A. Mastrucci and others, “Cooling access and energy requirements for adaptation to heat stress in megacities,” Mitigation and Adaptation Strategies for Global Change, vol. 27,
[36] Zhang L, Zhang Q, Rafiq MA. The economic and environmental analysis of solar energy development under climate impacts. Science Progress. 2022;105(3). https://doi.org/10.1177/00368504221124065
[37] M. Khan, M. M. Khan, M. Irfan, and others, “Energy performance enhancement of residential buildings in Pakistan by integrating phase change materials in building envelopes,” Energy Reports, vol. 8, pp. 9290–9307, 2022. https://doi.org/10.1016/j.egyr.2022.07.047
[38] Ahsan Mustafa, Muhammad Anwar, & Talha Irfan Khan. (2024). Energy optimization of an institutional building to reduce the energy and air conditioning demand. Journal of Building Engineering, https://doi.org/10.1016/j.jobe.2024.111309
[39] ISO, ISO 52000-1:2017 — Energy performance of buildings — Overarching EPB assessment — Part 1: General framework and procedures, International Organization for Standardization, 2017. https://www.iso.org/standard/65601.html
[40] B. Aboagye, S. Gyamfi, E. A. Ofosu, and S. Djordjevic, “Degradation analysis of installed solar photovoltaic (PV) modules under outdoor conditions in Ghana,” Energy Reports, vol. 7, pp. 6921–6932, 2021. https://doi.org/10.1016/j.egyr.2021.10.046
[41] Atia, D.M., Hassan, A.A., El-Madany, H.T. et al. Degradation and energy performance evaluation of mono-crystalline photovoltaic modules in Egypt. Sci Rep 13, 13066 (2023).https://doi.org/10.1038/s41598-023-40168-8
)