What Is Heat Gain in Windows in Your Sarasota, FL Home?

If you sit inside your Sarasota, FL home by a window on a sunny day, you can feel the heat of the sun through the glass. During the winter, this helps heat the interior. In Florida’s sunny climate, heat gain through windows can make the living space uncomfortable and cause your air conditioning system to work harder. There are ways to keep heat outside without tinting glass or blocking views.

Heat Gain Explained

Heat enters buildings in many ways. It travels through walls, penetrates roofing materials and infiltrates the building shell through cracks around windows and doors. Windows are a major source of heat gain and loss, accounting for approximately 25% of the energy used for heating and cooling a home. When the sun’s rays penetrate window glass, the result is the transfer of solar heat energy into the building.

The sun’s energy consists of a broad spectrum of radiation: ultraviolet, visible and near-infrared. Ultraviolet light has the shortest wavelength, which is invisible to humans. Near-infrared radiation, also called short-wavelength infrared energy, is the primary source of heat energy transmitted through glass into a building. Once inside, it heats objects and surfaces. The heat energy radiated by objects is long-wavelength infrared radiation, which is reabsorbed by the glass and emitted to the outside.

Measuring the Transfer of Heat

In cold climates, energy-efficient window coatings are designed to keep heat inside. However, in hot climates, window coatings are designed to prevent heat energy from entering the building and letting long-wavelength heat energy escape.</p p>The amount of solar heat energy transferred through windows is measured using the solar heat gain coefficient, 1 representing maximum heat gain, and 0 the least. If a window’s SHGC is .35, 35% of the available solar heat passes through.

U-factor ratings measure how much interior heat energy escapes through windows. A low number means less heat loss, desirable for cold climates. For warm climates, a higher U-factor is desirable.

If you are considering installing energy-efficient windows and doors in your Sarasota, FL home, call JMI Windows & Doors. Our hurricane-rated, energy-efficient and security windows and doors come from well-established manufacturers, including PGT, in many styles and materials. For more information, call JMI Windows & Doors. We are family-owned and -operated and back our work with a 100% customer satisfaction guarantee.