August is the hottest month of the year in much of the world, so keeping cool is on everyone’s agenda right now. Forget fans and air conditioning, an expert has shared one little-known tip to keep your home cool that doesn’t cost a penny. Simple rule to keep your home coolJohn Small, housebuilder and owner of Ty Eco, said you can keep your home as “cool as a cave” by following one simple rule: If it’s cooler inside than it is outside, you should keep your windows closed. As soon as it gets hot outside, everyone rushes to open all the windows in the house to ‘let the air in’, but you could be m…