## 1 Introduction  
Climate change remains a critical and topical issue affecting every aspect of the natural environment. The climate crisis is the biggest single threat to all of humanity, with devastating consequences that have the potential to reverse decades of progress and to thrust people into poverty. It is acknowledged that climate change is the direct result of natural causes, but predominantly attributable to anthropogenic activities, and numerous scientific studies firmly establish that global warming is responsible severely altering the balance in the globe's climate through the release of damaging greenhouse gases (GHGs). Energy expended in buildings alone accounts for an approximate one-third of total energy utilisation while being responsible for 20% of global GHG emissions [1]. The seriousness of the climate change problem caused largely by the extravagant use of fossil fuels creates the impetus to minimise or eliminate their consumption and thereby alleviate this troubling environmental malady. Thus, substitution of fossil fuels with renewable energies such as solar energy, wind energy, biomass and geothermal energy for combined heat and power (CHP) generation has been explored and very well received with increasing popularity in the last two decades. This has followed previous efforts at developing a micro-grid by deploying solar-based and renewable energy systems for building applications. In thermodynamic cycles, the organic Rankine cycle (ORC) has become increasingly deployed in CHP systems. ORC is currently being researched as a promising technology-based power system with a great potential for growth and which would likely compete with fossil fuels, particularly natural gas. Alike to the steam power cycle in which the working fluid (WF) used is vapour water, ORC also employs hydrocarbons (organic constituents) that have extra capacity than water to lower heat source temperatures for the intents of both power and CHP. Since ORC has the advantage of special features including an uncomplicated structure, greater reliability, and simpler repairs over other cycles, it is a convenient system for converting energy from low-temperature heat sources such as solar systems. Moreover, this device enables micro-scale utilisations in buildings [2; 3; 4; 5; 6; 7; 8]. The broad spectrum of potential applications have stimulated and inspired more investigations to derive suitable ORC-based solutions. Researchers and engineers are finding that the ORC system's technical performance is likely influenced by thermodynamic cycle design, expander technology and working fluid assortment. Increasingly, they are also examining positive or volumetric displacement expanders for the purpose of low-temperature and micro-scale ORC. Researchers are continuing to examine various micro-ORCs built for generating power [9; 10; 11; 12]. Thermodynamic cycle design, expander technology and WF choice tend to impact the technical performance of an ORC system in fundamental ways. Similarly, since ORC systems are powered by solar energy, it is crucial to select the appropriate WFs in order to achieve an operation that is both harmless and effective. Apart from thermophysical properties, other indices, especially those of chemical stability and the environmental effect, in addition to the cost factor require further research in order to accomplish desired results. WFs have been carefully considered and selected for solar-powered ORC systems. An ORC system's economics are mainly associated with a WF's thermodynamic requirements. A suitable WF would have certain definite properties, especially medium pressure within heat exchangers, small specific volumes and high efficiency, small ozone depletion potential (ODP), low global warming potential (GWP), and minor toxicity. Modest pricing would naturally be an additional factor for suitability. If the selection is inappropriate, it could result in a costly and ineffectual machine.