A well-placed skylight or roof window can completely transform an interior space. These overhead apertures can flood an otherwise dark room with natural light while the views they open up to the sky, clouds and weather conditions create a sense of connection with the outdoors. Specifying an operable roof window encourages the flow of air, with cross ventilation cooling a building's interior and mitigating the need for air conditioning. Conversely, double glazing reduces the loss of warmth in the colder months.