In recent years, renewable energy use has been increasing due to its pivotal role in mitigating the adverse effects of global warming. In particular, the Tokyo Metropolitan Government has begun requiring the installation of photovoltaic (PV) power generation systems in newly constructed houses to reduce greenhouse gas emissions in Tokyo by 50% by 2030, relative to the emissions recorded in 2000. Nonetheless, the intermittent nature of renewable energy sources such as PV power generation can result in discrepancies between electricity supply and demand, especially during consumer load fluctuations. Additionally, the increasing number of hot summer days has led to air conditioning significantly contributing to energy consumption. According to the Agency for Natural Resources and Energy, air conditioning accounts for approximately 57% of summer electricity consumption at 2 p.m. Therefore, energy savings in air conditioning will lead to lower electricity costs and environmental impact. However, considering the potential health risks associated with excessive energy conservation in air conditioning is crucial. To address these concerns, increasing renewable energy use can reduce health risks such as heatstroke. However, regardless of the introduction of PV power generation, electricity prices are rapidly increasing, and there is a growing trend toward lowering electricity consumption. Therefore, this study proposes the introduction of a hydrocarbon refrigerant (GF-08) and conducts a system analysis that considers the thermal environment in a residential setting. GF-08, a mixture of propane and propylene in a 1:1 volume ratio, has been reported to consume 28% less electricity than the conventional refrigerant R410A when used for cooling. The originality of this study is that, in addition to the environmental impact assessment pertaining to the cost of electricity consumption, heatstroke risk and other health hazards are also incorporated as indicators. This was achieved by combining PV power generation, an uncertain energy supply, energy use, and air conditioning while considering the hot thermal environment. Empirical data and computational methods, including computational fluid dynamics (CFD) modeling, were utilized. This study assumed a typical four-person family and evaluated the cost and environmental performances based on the differences in cooling usage methods and equipment throughout sleep. A CFD model estimated the hot and humid environment.