## 1 Introduction
\begin{table}
\begin{tabular}{c c} \hline \hline
**Limitation** & **Description** \\ \hline Energy Consumption & HVAC systems are often significant consumers of energy, contributing to high \\  & operational costs and environmental concerns. \\ \hline Installation Cost & The initial cost of purchasing and installing HVAC systems can be high, particularly for \\  & large or sophisticated systems. \\ \hline Maintenance Requirements & Regular maintenance is essential for HVAC systems to operate efficiently, which can \\  & incur additional costs and downtime. \\ \hline Space Requirements & Large HVAC units require considerable space, which can be a limitation in compact or \\  & densely built environments. \\ \hline Noise Levels & HVAC systems, especially older or larger units, can generate noise, potentially causing \\  & disturbance in quiet environments. \\ \hline Refrigerant Environmental Impact & Some HVAC systems use refrigerants that can contribute to ozone depletion and climate \\  & change if leaked. \\ \hline Indoor Air Quality & If not properly maintained, HVAC systems can contribute to poor indoor air quality by \\  & circulating dust, mould, and other contaminants. \\ \hline Temperature Inconsistencies & Achieving consistent temperatures in a building can be challenging, leading to hot or \\  & cold spots. \\ \hline Humidity Control Limitations & Some HVAC systems may struggle to maintain optimal humidity levels, affecting \\  & comfort and indoor air quality. \\ \hline Lifespan & The lifespan of HVAC systems can be limited, necessitating replacement or \\  & significant upgrades. \\ \hline Adaptability & Older HVAC systems might not be easily adaptable to new technologies or changing \\  & environmental regulations. \\ \hline Aesthetic Impact & Large and visible HVAC equipment can have a negative impact on building aesthetics. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The limitations of HVAC systems. To reconcile this dichotomy, scholars and practitioners have explored passive design strategies like natural ventilation, solar heating, and thermal mass, which can significantly reduce energy demand while maintaining or improving thermal comfort [17]. Advanced HVAC technologies are emerging as another solution; for example, Variable Refrigerant Flow (VRF) systems, radiant cooling systems, and chilled beams show significant promise of enhancing energy efficiency without compromising comfort [18]. The literature also increasingly focuses on adaptive and human-centric thermal comfort models, recognising that comfort is not a static, one-size-fits-all phenomenon but varies based on cultural, psychological, and individual physiological factors [19]. Internet of Things (IoT) technologies add another layer of sophistication by allowing for real-time monitoring and the adaptive control of multiple environmental parameters, thus enabling a more dynamic, responsive approach to achieving thermal comfort in green buildings, as shown in Figure 2[20]. Despite these developments, there are still knowledge gaps about effectively combining these varied tactics into a coherent, practical, and scalable strategy for boosting thermal comfort in green buildings. Thermal comfort, essential to the well-being of building occupants, has been widely investigated, demonstrating its dependence on parameters such as air temperature, radiant temperature, humidity, air velocity, and human characteristics, such as clothing and metabolism [21]. While traditional HVAC systems attempt to standardise these factors, they often fall short in energy efficiency and flexibility [22]. Especially in the field of green buildings, where the emphasis is placed on both comfort and environmental sustainability, traditional HVAC systems often fail to satisfy both goals [23]. The energy-intensive nature of current HVAC systems, which contributes to high operating costs and greenhouse gas emissions, is one of the greatest obstacles [21; 22].