Skylights are windows that are placed on the roof. They are used to allow natural light to enter, and can also be used to allow air ventilation. There are many details to consider when choosing a skylight including size, placement, energy efficiency, functionality, and type.
When selecting a skylight, size is an important factor because if the skylight it too large then it will bring in too much light and heat. Often, the rule is that a skylight will be able to brighten a room twenty times its size. Just as important is the placement of the skylight. Placing a skylight where there is a lot of sun-exposure can lead to the room getting overheated, especially in warmer climates. Typically, a northern or eastern exposure position is recommended.
Energy-efficient window selection is also important when installing a skylight. Glazing is one way to improve energy savings. Skylight glazing often comes in plastic or glass, but other solar heat-control glazing may also be available. Plastic glazing is often inexpensive, and sturdier than other glazing materials. However, plastic glaze allows ultraviolet (UV) rays inside, which can result in discoloration of objects inside the room. Glass skylight glaze are more expensive, but are also more durable and do not discolor.
Skylights often have one of three functions: allowing natural light in, ventilation, or moisture control. Light-emitting or day lighting skylights use traditional fixed designs, which capture the light and reduce overheating and heat loss. However, this type of skylight does not open to provide ventilation or a view.
Ventilation skylights let out heat that accumulates near the ceiling. These skylights often vent out of a hinged panel, and are often used in small spaces like kitchens or bathrooms to relieve moisture and regulate airflow. Moisture control skylights are also available. These skylights have an interior channel, which catches condensation so that it can evaporate later.