What is the SHGC of a window?
Solar heat gain coefficient (SHGC) is the fraction of solar radiation admitted through a window, door, or skylight — either transmitted directly and/or absorbed, and subsequently released as heat inside a home. The lower the SHGC, the less solar heat it transmits and the greater its shading ability.
What is a good SHGC?
When it comes to an optimal SHGC rating, again you will want to look for a rating of 0.25 or less for efficient energy performance and lower A/C costs. Although for people that like their home on the warmer side should choose a SHGC rating between 0.35-0.60 to allow natural solar heat in.
What is SHGC and U value?
U value is the measure of the insulating capacity of the glass. This represents how quickly heat from hot air (not direct sunlight) will pass through the glass. Solar Heat Gain Co-efficient (SHGC) is the amount of heat from direct sunlight that passes through the glass.
What does Vt mean for windows?
Visible transmittance
Visible transmittance (VT – expressed as a number from 0 to 1) also known as Visible light transmission (VLT – expressed as a percentage %) is a measurement of the amount of light in the visible portion of the spectrum that passes through glass.
How do I read SHGC?
SHGC is best described as a ratio where 1 equals the maximum amount of solar heat allowed through a window, and 0 equals the least amount possible allowed through. An SHGC rating of 0.30 means that 30% of the available solar heat can pass through the window.
What is a window U-value?
The U-Factor measures how well the window in- sulates. While the U-Factor can take any value, in general for windows it ranges from 0.20 to 1.20. The lower the U-Factor, the better the window insulates. The SHGC measures how much of the sun’s heat comes through the window. It can range in value from 0 to 1.
Do you want low SHGC?
Solar Heat Gain Coefficient and Climates You’ll want to, generally, choose windows with a low SHGC rating if you live in a warm climate. For windows that are west-facing and south-facing, you might consider low SHGC rated windows to help with that hot afternoon sun.
How can I reduce my SHGC?
SHGC and U-factor can be reduced in the glass portion of a window assembly in a number of ways: Low-emissivity (low-e) coatings reduce the ultraviolet and infrared light that passes through the glass, limiting heat gain while preserving visible light transmission.
What is a good VT for a window?
between 0.30 and 0.70
Most double- and triple-glazed windows have VT values between 0.30 and 0.70. Higher VT is desirable, but lower VT values are often delivered along with lower U-factors. If you get a really high-performing window, beware of VT values less than 0.40. Below that point, your view may start to have a grayish cast.
What is the U value of a window?
0.20 to 1.20
The U-Factor measures how well the window in- sulates. While the U-Factor can take any value, in general for windows it ranges from 0.20 to 1.20. The lower the U-Factor, the better the window insulates. The SHGC measures how much of the sun’s heat comes through the window.
How is window U-value calculated?
Calculation of U-value of windows. Heat loss = U x A x dT where U = U-value (W/m2K)Thermal transmittance A = Area of surface (m2) dT = Temperature difference inside to outside ( K ) Units of heat loss = Watts.