Energy Conversion and Management 291 (2023) 117301 0196-8904/© 2023 Elsevier Ltd. All rights reserved. Nano-enhanced thermal energy storage coupled to a hybrid renewable system for a high-rise zero emission building Reza Daneshazarian , Umberto Berardi * Toronto Metropolitan University, 350 Victoria St., Toronto M5B 2K3, Ontario, Canada A R T I C L E INFO Keywords: Ground Source Heat Pump Net Zero Emission Polygeneration Renewable Energy ABSTRACT Renewable energy sources suffer from intermittent availability. Adding a latent heat thermal energy storage (TES) is often proposed as an effcient solution to address their stability. In this study, a hybrid renewable energy system consisting of solar photovoltaic panels, evacuated tube collectors, and a ground source heat pump (GSHP) is investigated. The system was coupled with an underground nano-enhanced TES system for improved per- formance to meet the energy demand of a high-rise residential building in Toronto, Canada. The applied energy storage system in this study consists of nano-enhanced phase change material pipes buried vertically under- ground to address the temperature stability of the ground. To investigate the effectiveness of this hybrid renewable energy system, a novel co-simulation methodology is adopted. The effciency of this system is ana- lysed on the component-scale using CFD simulations. The results show that adding nanoparticles increases the thermal storage capacity of the GSHP by 26.4 %. Then the impact of the hybrid renewable energy system with improved storage capacity on the building scale was assessed using TRNSYS. The economic, environmental, and energy consumption impacts of the proposed system was evaluated. Without TES, 296 borehole heat exchangers with a depth of 243 m would be needed to meet the heat and cooling demand; however, considering the modifed ground source heat pump, the number of boreholes were reduced to 197 with a depth of 163 m. The results showed a signifcant impact on the drilling cost reduction, and the life span increase of the geo-exchange system. The coeffcient of performance of the fnal system increases by 27.1 %, while the building energy consumption decreases by 36.7 %. 1. Introduction The building sector represents a major share of Canada’s energy demand, accounting for about a quarter of total fnal energy consump- tion. Particularly, the need to focus on building energy demand within urban areas is critical as urban areas are responsible for the largest share of GHG emissions [1]. The increase in the rate of urbanization directly points to higher demand for energy use in buildings due to population increase and higher living standards. Higher energy demand in buildings then translates to increased GHG emissions [2]. New building con- struction continues to be a strong driver of demand for energy services, however, the large number of existing buildings in urban areas in Can- ada require signifcant attention for deep energy retrofts and upgrade in energy systems [3]. Canada’s climate strongly infuences energy use for needs such as heating and cooling, which together represent around 41.6 % of the sector’s energy consumption [2,4]. Usually, the heating demand is higher than the cooling demand; however, the projections about the energy demand for 2050 show that the cooling demand will increase more prominently [5]. The future climate uncertainty in Can- ada similar to the rest of the world shows the importance of new building systems and energy strategies that can not only respond to the current needs but can also adapt to the future climate variations [5]. The city of Toronto is the largest urban area in Canada with fast urbanization and population growth. The largest share of energy use in Toronto for space heating and cooling belongs to multi-unit and high- rise resdiential buildings and commercial buildings [6]. In addition to this existing building stock, Toronto has the largest share of the new high-rise buildings approved for construction in North America, mainly according to the Ontario Building Code [1,7] and the Toronto Green Standard [8]. Given the nature of recent construction practices and increasing trends of urbanization, and high-density living areas, high- rise residential and commercial buildings are becoming the normal building types. Therefore, reducing GHG emissions due to energy use in such buildings is critical, by frst reducing the demand for energy, and increasing the reliance on renewable energy sources. Studying how to * Corresponding author. E-mail address: uberardi@torontomu.ca (U. Berardi). Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman https://doi.org/10.1016/j.enconman.2023.117301 Received 25 March 2023; Received in revised form 9 June 2023; Accepted 10 June 2023