Thermal Energy Storage (TES) is a method of temporarily storing high or low-temperature energy for later use, serving as a bridge between energy requirements and energy utilization. In HVAC and refrigeration applications, water and water ice are commonly used as the primary storage media. Water has the advantage of being universally available and cost-effective. However, if one wishes to utilise its latent heat capacity, it can only be produced using inefficient low-temperature refrigeration units. Moreover, if water is used solely for sensible energy storage, it necessitates large storage tanks due to its lower energy density. To overcome these limitations, Phase Change Materials (PCMs) offer a practical solution. PCMs have a phase transition temperature range between +4°C (39°F) and +90°C (194°F), allowing them to combine both latent and sensible energy storage capacities within a single storage unit. This characteristic opens up new possibilities and practical applications for designers. While conventional solar thermal collectors may not generate enough energy to fully charge a hot water tank during winter, they can generate sufficient low-grade heat, typically around 30 to 35°C (86°F to 95°F), which is more than enough to charge PCM modules with a phase transition temperature of 27°C (81°F) during daytime. As the sun sets, the stored energy in the PCM modules keeps the occupied space warm, while the cold energy from the outside freezes the PCM, preventing it from penetrating into the occupied space. This allows for stable space conditions throughout the 24-hour day and night cycle. Relying solely either on primary solar energy or as top up input not only provides environmentally-friendly heating but also eliminates / reduces the costs associated with gas, fossil fuel, or electricity. This makes it an attractive and economical heating option. However, in colder climates where solar energy alone may not provide 100% free heating, a small ground or air-water heat pump can be utilised. By storing daytime solar energy for evening periods, a PCM system can address the overnight heating requirements. Thus, the PCM system acts as a bridge between energy availability and energy utilization, offering significant environmental and economic benefits for various heating applications. Overall, Thermal Energy Storage systems, particularly those incorporating PCMs, present promising opportunities to optimize energy usage, enhance sustainability, and provide cost-effective heating solutions.