Glassary - E

EN 357 classification for integrity, fire resistant glass.

Pilkington Eclipse™ is our brand name for a range of hard coated, solar control glasses. See Product Data Sheet Pilkington Eclipse™.

Edge clearance:
the distance between the edge of the pane and the frame in which it is glazed. The clearance is required to allow for tolerances, avoid contact between the glass and it's framing and, in the case of drained glazing, to give sufficient room for water to drain away.

Edge cover:
the amount of glass within the rebate, i.e. covered by glazing bead. This is required to ensure the pane is effectively secured (i.e. a mechanical requirement) and also to ensure the edge seal of an insulating glass unit is protected from the weather.

Edge seal:
the hermetic seal around the edge of an insulating glass unit, designed to limit the rate at which water vapour penetrates into the cavity. The better performing edge seals are usually dual seal systems. These are used in Pilkington Insulight™ Units.

Edge Work:
any extra work carried out to the edge of a piece of glass. This can be arrissed edge, a flat ground edge or a polished edge. It may be used to refer to bevelling the edge of the glass.

Effective U value:
sometimes called the energy balance value, a measure of the performance of glass as an energy saving wall construction when its ability to let in useful solar heat gains is combined with its capability for thermal insulation as described by the U value. There is further information on this in Technical Bulletin Glass and Energy Management Thermal Insulation.

EN 357 classification for Insulation, fire resistant glass.

EKO Plus:
hard coated, Low Emissivity Glass produced by St Gobain. Pilkington K Glass™ should be offered as a substitute.

Electromagnetic attenuation:
see electromagnetic shielding.

Electromagnetic radiation:
a technical expression for all the wavelengths of electrical or magnetic activity. The full spectrum from cosmic and gamma rays with very short wavelength, through X-rays, UV light (generally described as 280 to 380 nanometre (nm) wavelength), visible spectrum (generally described as 380 to 780) and infra-red, to radio waves with very long wavelength. There is further information in Product Data Sheet Pilkington Datastop™.

Electromagnetic shielding:
the use of a Faraday Cage to reduce or prevent the passage of the longer wavelengths of electromagnetic radiation, usually at the frequencies of radar and radio waves. The electromagnetic attenuation give by the Faraday Cage is measured in decibels. There is further information in Product Data Sheet Pilkington Datastop™.

the ability of a surface to absorb or emit electromagnetic radiation. In terms of glass, emissivity is only important with respect to long wavelength radiation (in the range 5000 to 5000nm) produced as radiated heat by objects at around room temperature. Glass naturally has a high emissivity. However, when made into low emissivity (Low E Glass), the glass surface does not absorb the radiated heat, but reflects it back into the room, enhancing the U value of the glazing. Pilkington K Glass™ and Pilkington Optitherm™ are examples of Low Emissivity Glass.

European standard #. These are being adopted as British standards and so become BS EN#. A list of these appears amongst the British Standards at the back of this guide. Enamel:
a glassy material, which is melted into the surface of the base glass at high temperatures to form a ceramic coating.

Enamelled glass:
glass with enamel applied. Used in Pilkington Spandrel Glass, see spandrel panel. See Product Data Sheet Pilkington Spandrel Glass for more information.

End Cap:
wooden boxes held onto the ends of a pack of glass with metal banding. One of the standard methods of delivery for larger quantities of glass.

Energy Balance Value:
also known as the effective U value.

Environmental control:
a term used to describe a glass or glazing product which is used for particular effect on the environment inside a building. Often used as a euphemism for solar control it could also refer to sound insulation, thermal insulation, and the control of lighting levels or a combination of all of these.

Pilkington Everglade™ is the brand name for one of the Pilkington Texture Glass™ range (see consumer leaflet Pilkington Texture Glass™ of patterned glass. Pilkington Everglade™ has an obscuration level of 5.

EN 357 classification for partial insulation or reduced heat radiation, fire resistant glass.

Explosion resistance:
see blast resistance.

Ext. AA:
see reaction to fire.

External AA:
see ext. AA.

External applications:
applications where glass or glazing products are used in positions exposed to natural weather.

External condensation:
condensation forming on the external face (surface 1) of glazing with very low U values. The effect requires particular combinations of high external humidity, average temperatures and exposure of the glass to clear night sky. There is more information in Technical Bulletin Glass and Energy Management Thermal Insulation.