There can be several reasons why your house may feel hotter than outside even when the windows are open and there is airflow. Here are a few possibilities to consider:
Sunlight and heat radiation: The sun's rays can enter your house through windows, heating up the interior. Even with open windows and airflow, the heat from sunlight can contribute to a warmer indoor temperature.
Heat transfer from the walls and roof: The walls and roof of your house can absorb heat from the sun and transfer it inside, raising the temperature. This heat transfer can continue even if the windows are open.
Inadequate ventilation: While you mentioned having open windows and airflow, it's possible that the airflow is not sufficient to remove the heat from the house effectively. If there are obstructions blocking the airflow or the ventilation system is not properly designed, the hot air may remain trapped inside, leading to a higher indoor temperature.
Heat sources inside the house: Appliances, lighting, and human activity can generate heat within the house. If there are multiple heat sources operating simultaneously, they can contribute to the overall temperature increase.
Humidity: High humidity levels can make the air feel warmer, even if the actual temperature is not significantly high. If the outside air is more humid than the indoor air, it can make your house feel hotter.
Thermal insulation: The insulation of your house plays a crucial role in maintaining indoor temperatures. If your house has poor insulation, it can allow heat to seep in from outside, making the interior hotter.
It's important to note that each house is unique, and the specific factors affecting the temperature inside can vary. If you are experiencing consistently high temperatures inside your house despite open windows and airflow, you may want to consider consulting an HVAC specialist or a professional energy auditor to assess your house's specific conditions and provide tailored recommendations.