## 8 Economic Feasibility and Scalability  
Eco-friendly HVAC technologies, pivotal in sustainable building design, markedly outperform traditional systems in energy efficiency and environmental impact [74]. Geothermal heat pumps, a standout example, are exceptionally efficient, offering an impressive energy efficiency ratio (EER) of about 10-14, compared to 9-10 for conventional systems [75]. They can deliver three to four units of energy for every one unit of electrical energy consumed. Solar-powered HVAC systems, while dependent on geographic and solar conditions, significantly cut down on electricity usage and are often capable of reducing energy bills by 20-40% [76]. Energy recovery ventilators (ERVs) enhance indoor air quality and can decrease HVAC energy consumption by up to 40%, depending on the climate and building design [76]. These systems lower operational costs and drastically reduce carbon emissions, aligning with global sustainability goals. The upfront costs for these technologies are generally higher, but the long-term savings--evidenced by their superior performance figures--are substantial, making them increasingly preferred in modern, eco-conscious construction projects. In a detailed cost analysis of HVAC systems, contrasting traditional with eco-innovative models reveals distinct differences in financial implications and ROI [77]. Conventional HVAC systems, while cheaper to install, incur higher operational and maintenance costs over time due to less efficient energy use and frequent servicing needs. By contrast, eco-innovative HVAC systems, though more expensive initially, offer greater energy efficiency, leading to significantly lower operational costs [77]. The maintenance expenses for these advanced systems are often reduced due to their superior build quality and durability. The ROI for eco-innovative systems is favourable, as substantial long-term energy bills and maintenance savings balance the higher upfront costs. Additionally, many regions offer incentives like tax rebates for green technology adoption, enhancing the financial appeal of these systems. Another critical factor influencing the cost and implementation of HVAC systems is the impact of building codes and regulations, which vary regionally [78]. Stricter energy efficiency standards and sustainability requirements often favour eco-innovative systems, as traditional models may not comply with newer, more stringent regulations. This regulatory environment can significantly affect decision-making, pushing stakeholders towards more sustainable and compliant HVAC solutions. Therefore, while the initial investment in eco-innovative HVAC systems is higher, their long-term economic and environmental benefits and the increasing regulatory push towards sustainability present a compelling case for their adoption in modern building design [78]. When delving into the legal implications and performance of HVAC systems in different climates, a detailed understanding is crucial for sustainable building design. Legally, the implementation of HVAC systems is deeply intertwined with regional building codes and energy efficiency regulations. These laws vary widely, often dictating stringent standards that traditional HVAC systems may struggle to meet. Eco-innovative systems, designed with energy efficiency and sustainability in mind, are more likely to align with these regulations, thereby reducing the risk of legal non-compliance for building owners and developers [79]. Non-compliance can lead to penalties, legal disputes, and additional costs, making regulatory adherence a critical factor in HVAC system selection. Furthermore, these legal frameworks are dynamic and frequently updated to reflect new environmental goals or technological advancements, necessitating HVAC systems that can adapt to evolving standards. Performance in different climates is another critical aspect.