10. Ventilating rooms through windows

Using air conditioning devices for cooling air in rooms could be expensive and polluting. Air conditioning devices use a lot of energy and therefore they indirectly produce CO2 and other pollution (in power plants where electricity is produced). If it is possible try to cool down and ventilate rooms through windows in the evening or in the morning when outside air is cooler and fresh.
Impact: reduce electricity consumption, save money, reduce pollution