Spacing between layers of glass

Interior · Windows, Skylights and Solariums · printed page 363 (PDF page 364)

Book index entries

Glass – Spacing in Windows Spacing between Layers of Glass and Windows Skylight – Window and Solarium from the Inside and Window and Skylight from the Inside Skylight and Solarium from the Inside

Text in the illustration

spacing too small - conductive heat loss
spacing too large - creation of convective loops
spacing correct - about 5/8"
heat loss
outside glass
inside glass
less heat loss
metal spacers have greater thermal conductivity than rubber spacers (let more heat escape)
more heat loss
more heat is lost around the edge of a window (through the sash) than in the middle of the window - this is called edge effect
cross section

Generated explanation

The illustration shows a cross section of a double-glazed window with enlarged details comparing spacing between the glass layers. A narrow gap is marked incorrect because of conductive heat loss, while an overly wide gap is marked incorrect because it creates convective loops. A gap of about 5/8 inch is marked correct. An enlarged edge detail shows greater heat loss through the sash and glazing edge than through the middle of the glass, identified as the edge effect. An annotation explains that metal spacers conduct more heat than rubber spacers.