Glass

Clear advantages

Single-glazed standard 4mm float glass, commonly found in older homes without replacement windows or double glazing, exhibits inadequate thermal insulation properties. Specifically, it allows the transmission of heat energy at a rate of around 5.8 Wm-2K. In contrast, current Building Regulations mandate a minimum standard of 1.4 Wm-2K, which translates to being nearly five times less efficient in retaining heat. Early models of double glazing, introduced in the 1980s and 1990s, offered modest improvements with a heat transmission rate of 2.8 Wm-2K, although they still fell short of modern double and triple glazing standards.

Standard float glass often displays a faint green tint, which is a result of iron impurities in the sand used to manufacture the glass. These iron ions absorb light across the red and infrared spectrum, as well as the blue and ultraviolet spectrum, causing the glass to appear green. Despite this characteristic green hue, standard 4mm float glass manages to transmit approximately 90% of available light through it.