ENERGY PERFORMANCE RATING
ENERGY PERFORMANCE RATING
THERMAL: U-factor, Solar Heat Gain Coefficient (SHGC), and Visible Transmittance (VT) are all important measures of a window's energy performance.
U-factor: The U-factor measures how well a window can prevent heat from escaping from a building. It is a measure of a window's thermal conductivity, or how easily heat can pass through it. A lower U-factor indicates that a window is better at insulating and keeping heat inside a building during cold weather.
Solar Heat Gain Coefficient (SHGC): The SHGC measures how much solar radiation is allowed to pass through a window. It is a measure of the ability of a window to transmit solar energy into a building, and it is expressed as a number between 0 and 1. A higher SHGC indicates that a window is better at letting in solar heat during the winter months, but it can also lead to more heat gain during the summer.
Visible Transmittance (VT): The VT measures the amount of visible light that can pass through a window. It is a measure of a window's ability to allow natural light into a building. A higher VT indicates that a window is better at transmitting visible light, which can help reduce the need for artificial lighting.
A Passive Low-E coating, also known as a low-emissivity coating, is a type of coating applied to glass surfaces to improve the energy efficiency of windows. The coating is designed to reduce the amount of heat that is transferred through the glass, by reflecting some of the infrared radiation that is emitted from warm objects.
Passive Low-E coatings work by reflecting long-wave infrared radiation back into a room, while allowing visible light to pass through the glass. This means that in the winter, the coating can help keep heat inside a building, reducing heating costs. In the summer, the coating can reduce the amount of heat that enters a building, reducing cooling costs.
Passive low-e coatings are different from active low-e coatings, which use electricity to control the amount of heat that is transmitted through the glass. Passive low-e coatings are also different from traditional coatings, which are designed to simply block UV rays and visible light, without affecting the transfer of heat.
Examples: Cardinal LoE-366; Guardian ClimaGuard Premium2; Pilkington K Glass; AGC Planibel G; Saint-Gobain SGG Planitherm Total
Solar Control Low-E (low emissivity) coating is a type of coating applied to glass surfaces that provides both low emissivity and solar control properties. This type of coating is designed to reflect a high amount of the sun's energy (in the form of solar radiation) away from the glass, while also reducing the amount of heat that is transferred through the glass.
Solar control low-e coatings are particularly useful in hot climates or areas where there is a lot of direct sunlight, as they can significantly reduce the amount of solar heat gain that enters a building through the windows. By reflecting away a high percentage of the sun's energy, the coating can help to reduce the amount of energy needed to cool a building, thereby reducing cooling costs and improving energy efficiency.
Additionally, the low emissivity properties of the coating also help to improve insulation, by reflecting the infrared radiation emitted by objects inside the building back into the room, helping to keep the interior temperature stable and reducing heating costs in colder climates.
Examples: PPG Solarban 60; Guardian SunGuard SuperNeutral 68; Vitro Solarban 70XL: AGC Stopray Ultra; Saint-Gobain Cool-Lite SKN 174
Hard coat low-e coatings are thicker, more durable, and can be used in high-traffic areas, while soft coat low-e coatings are thinner, more efficient at reflecting heat, but require additional protection to prevent damage or degradation.