The rapid urban spatial expansion and population growth in recent years has resulted in the development of numerous high-rise condominiums in Kuala Lumpur. Many of these buildings include general relaxation and recreational facilities for the occupants. However, the majority of these spaces are designed to cater for the basic needs of typical residents, with less attention to the expectations of the elderlies. As a result, elderlies residing in such condominiums predominantly prefer to stay in their flats, and this phenomenon can negatively impact their overall health and quality of life. While with an appropriate consideration of shared facilities this occurrence can be solved. In this study, cool colours in fifteen intensities were tested (10 minutes as the test duration for each intensity) on 64 elderly occupants in a 3m×2m test room based on the Quasi-experimental method to evaluate the impacts of cool colours as environmental stimulus in common indoor facilities of condominiums. The participants were the residents of two high-rise condominiums in Kuala Lumpur, and they were all above 60 years old. Their blood pressure, heart beat rate and skin temperature as dependent variables were measured by sphygmomanometer and infrared thermometer as two required instruments and analysed to evaluate their relationship with cool colours and time spent. There are three significant results: Firstly, the lightest intensity of bluegreen and green colours have decreased dependent variables with strongest relationship. Secondly, violet has negative impacts by increasing dependent variables. And thirdly, green colour, in general, has decreased dependent variables with positive impact as environmental stimulus while lightest blue-green colour affects the dependents variable faster than the other intensities. Higher rate of dependent variables associated with arousing feeling, while lower rate of dependent variables associated with calm and relaxation feeling. The study concludes that particular cool colours embrace promising potentials to be taken into consideration during the design of indoor spaces, particularly for the elderlies, by architects and interior designers.