Reflecting the sunlight away will reduce the heating you get from the sun. As far as opening a window or not, open if outside is cooler, else close.
If it's pretty windy then it may be worth opening the window if the temperature is similar.
Reflecting the sunlight away will reduce the heating you get from the sun. As far as opening a window or not, open if outside is cooler, else close.
If it's pretty windy then it may be worth opening the window if the temperature is similar.