To keep a house cool, it is generally more effective to keep the windows open on the bottom floor rather than the top floor. This strategy takes advantage of the principle of natural convection and helps create a cooling airflow throughout the house.
Here's why opening windows on the bottom floor is more effective:
Natural convection: Warm air rises, and cool air sinks. When you open windows on the bottom floor, cooler outside air can enter the house and displace warmer indoor air. As the warmer air rises, it will find its way out through the windows on the top floor, creating a natural flow of air that helps cool the entire house.
Cross-ventilation: If you have windows on opposite sides of the house, opening windows on the bottom floor will allow for cross-ventilation. This means that as cool air enters from one side, it pushes out warm air through the windows on the other side, enhancing the cooling effect.
Shading effect: Keeping windows on the top floor closed helps to reduce the amount of direct sunlight and heat entering the upper levels of the house. This can significantly lower the indoor temperature and reduce the need for air conditioning.
Safety and security: Opening windows on the top floor may pose safety and security risks, especially if they are easily accessible from the ground. Keeping windows on the bottom floor open is safer and reduces the chances of accidents.
It's important to note that the effectiveness of this strategy depends on the outdoor weather conditions. If the outdoor air is extremely hot or humid, it may not be beneficial to open windows for cooling. In such cases, using shades, curtains, or blinds to block direct sunlight and heat can be a more effective way to keep the house cool.
Additionally, during cooler parts of the day, such as evenings and early mornings, it's best to open all windows and take advantage of natural ventilation to cool down the house. However, as the outdoor temperature rises during the day, you may need to close windows and use fans or air conditioning to maintain a comfortable indoor environment.