The upper levels of homes and cottages are often difficult to keep cool in summer. Hot air rises and stays in upper storey areas, unless you give it a chance to escape. Even central air conditioning can’t always beat the pockets of hot air that get trapped in top-floor bedrooms. This is why so many people have basements made freezing cold by air conditioning, while bedrooms upstairs are way too hot.
The video tutorial below shows the simple but effective way that openable skylights allow hot air to rise from warm areas of a building. This lets cooler, fresher air from open windows and air condition move upwards through lower-floor windows in a way that has to be felt to be believed. It really makes a big difference. I first learned this with some cabins I built, but it applies equally well to full-size homes. Click below to watch a video where I explain the context as part of my online cabin building video course called Cozy Cabin.