Skylights let natural light stream into your home, bringing warmth and a feeling of spaciousness. When properly selected and used, they can reduce your need for electric lighting and minimize your heating and cooling costs. Skylights can provide up to 30% more natural light than vertical windows while making a small space seem bigger. A skylight is like a window which has been placed in your roof. It has a frame specially designed to withstand rain and prevent leakage from rain and snow. To maximize a skylight's use of natural light to illuminate a room or its passive solar heating potential, you will want to take into consideration how a skylight is positioned.
Facing north, your skylight will provide fairly constant illumination, but will not provide a lot of heat.
Facing east, it will provide the maximum amount of light and solar heat gain in the morning.
Facing west, your skylight provides afternoon sunlight as well as heat gain.
A skylight facing south provides the greatest potential for winter passive solar heat gain than any other location, but will often allow unwanted heat gain in the summer. This heat gain can be minimized installing your south-facing skylight in the shade of deciduous trees or adding a moving window covering. Skylights come in all shapes and sizes. Its size greatly affects the illumination level and temperature of the space below. As a rule of thumb, the size of a skylight should never be more than 5 percent of the floor area in rooms with many windows; and no more than 15 percent of the room's total floor area for spaces with few windows. Dept. of Energy.
Like windows, skylight manufacturers use glazing to improve their energy efficiency. The glazing comes in three different forms.
Plastic glazing - This type of glazing is usually inexpensive and less likely to break than other glazing materials. However, these surfaces scratch easily and can become brittle and discolored.
Glass glazing - This is found in the more expensive skylights. It is more durable than plastic and does not discolor. All glass used for skylights must be made of "safety glazing," a generic term for both tempered and laminated glass. Tempered glass is the most impact resistant. Laminated glass is fabricated with a thin layer of plastic embedded near the center of the glass. Both types keep the glass from breaking into large, sharp pieces. Skylights are often made with a tempered glass on the exterior side and a laminated pane on the interior side. This arrangement gives maximum impact resistance while protecting occupants from falling shards of glass.
Solar heat control glazing - Manufacturers use various glazing methods to reduce the impact of summer solar heat gains and winter time heat losses. These come in the form of heat-absorbing tints, double and tripled pane skylights and low-emissivity coatings.
When your window professional installs your skylight, one of the factors they will take into consideration is the slope. The slope, or tilt of the skylight, affects the amount of solar heat gain. A low slope on your skylight admits more solar heat in the summer and less in the winter, which is the opposite of the effect you are trying to achieve. As a rule of thumb, you want to achieve a slope equal to your geographical latitude plus 5 to 15 degrees. For example, the optimum slope for a south-facing skylight in Columbus, Ohio, at 40º North latitude, is 45º to 55º. Every skylight has a "shaft" which governs how much light is admitted into the room below. If all four sides are flared, then the light is spread over a wide area. If your skylight has a shaft with perpendicular sides, the light is focused straight below. If your skylight's shaft is flared on only one or two sides, then the light is sprayed in the flared direction.
If you wish, you can have a skylight which also provides ventilation as well as light to your room. This allows you to release the hot air which collects at your ceiling. Ventilating skylight can be operated by one of three ways:
Manual skylight controls - These are opened by your use of an extended rod to manually crank the skylight open. These are designed for ceilings of less than 15 feet.
Electronic skylight controls - A simpler model of this type of control is wired to a wall mounted switch which opens and closes the skylight. More complex models are controlled by a special wall console of a wireless remote control.
Automatic operating controls - With this type of control, integrated heat sensors trigger the skylight to open when the interior heat reaches a preset temperature. Exterior sensors automatically close the unit when they sense moisture.
An alternative to the conventional skylight, which looks like a window in your roof, is the tubular skylight. The tubular skylight is a roof-mounted dome which collects natural light and delivers it to the room below. It is less expensive than the conventional skylight because it is designed to fit between roof and ceiling framing, eliminating the need for structural modifications. You will commonly see these used in bathrooms, hallways and closets, but they can be used in any room of your house. The average tubular skylight ranges in size from 10 - 21 inches in diameter, which lights a 100-600 square foot interior space. Skylights of any type transform a room by adding warmth and depth while bringing out the natural beauty of your home and its surroundings. When planning your new home or the remodel of your current one, take some time to consider skylights as a beautiful enhancement that also provide comfort to you and your family while conserving the energy we all share.