I use a davis vantage vu weather station, it is very accurate. When outdoor temperature is close to indoor temperature or if there is sun about to strike the east side of my house, then my open windows and doors on that side are closed and wooden insulating plantation shutters are also closed. Ok it is like a cave on that side but I can usually drop the house temperature by 3 degrees if I get up early enough. I never leave windows open downstairs overnight, for obvious reasons
I make sure that there is a good blow through before the sun hits the house. Thermal mass will store heat during higher daytime temperatures and release this heat during the night. It is all about managing solar gain and doing the pro-active stuff before the sun gets to it.
Yes ladymuck is correct, VOCs are volatile gases and they rise, they are easily swept out by having a blow through. Given off by many modern building materials, furniture, carpets, flooring