This report investigates the potential use of Phase Change Material (PCM) technology in poorly insulated lightweight homes in the Netherlands. The aim is to develop a cost-effective and easy-to-install PCM product that can decrease energy consumption through passive heating and cooling. The proposed design involves a multi-layer curtain system with small PET macroencapsulations containing salt hydrate attached to a sheer curtain. The system also includes a secondary insulation layer made of polyester with a reflective aluminum lining as a thermal barrier. MATLAB simulations indicate that this system, with 16 liters of PCM, can reduce heating loads by 7-9% when applied to a living room bay window measuring 4.46 m2 within a 28.8 m2 room. However, the insulation layer provides the most significant heat loss reduction. The simulation results also demonstrate a lower average summer temperature when the insulation curtain is not applied, suggesting effectiveness in both summer and winter. The estimated payback period for the system, based on the Dutch gas price cap of
€1.45 per m³, is 5 - 8.5 years. The report concludes that while the proposed PCM system has the potential to reduce energy usage in lightweight homes, further research is necessary to determine its actual effectiveness.