GLOSSARY-H

Header

The upper horizontal member of the main frame of a door, or a window frame.

Heat absorbing glass

(Tinted glass) - Window or door glass containing chemicals (with gray, bronze, blue or green tint) which absorb light and heat radiation, and reduce glare and brightness. Shading coefficient of this glass varies from about 50% to 70%.

Heat transfer coefficient

(U-value) - A value indicating the rate of heat flow through a building construction, expressed in units of Btuh per square foot of surface per degree F. difference between indoor and outdoor air temperature. This is numerically equal to the inverse of the sum of R-values for the construction.

Hinge

A movable joint enabling a window or a door to swing open.

Horizontal sliding window

(Horizontal slider) Windows which slide horizontally.

Hung window

Window with one or more hanging sashes.

Hygroscopic

The ability to 'give off' and 'take on' moisture, as in wood exposed to changes in relative humidity of air.