www.bulit-glass.bg>Products and Services> Insulating Glass

Insulating Glass

What is an insulating glass unit:

Insulating Glass Units (IGUs) are hermetically sealed combinations of two or more panes of glass separated by a dry airspace. IGUs improve the thermal performance of windows, thus significantly reducing heating and air-conditioning costs. IGUs also reduce interior condensation in cold climates, and increase comfort near windows, thus maximizing usable interor space.

Insulating Glass Units


In order to ensure best quality and warranty of our products, we need to use precise and automated equippment. In late 2005 we opened up a new state of the art facility for insulating glass units production. We equipped it with a fully automated assembly line and a sealing robot, both manufactured by the leading name in the field Lisec, Austria. Thus we are able to fulfil our customers" high quality demands in short period of time.

Insulating Glass Units

When choosing an insulating glass unit:

There exists a big variety of glass types to choose from, which could be misleading for the unprepared shopper. In order to make the right decision it is very important to first analyse the environment where the IGU will be installed. The more important criteria is:

  • The purpose of the building
  • Climate conditions near the bulding
  • The position of the facades in respect to the sun and the surrounding wind flows
  • The owner"s/investor"s stand point about future heating and air conditioning costs
  • Material resources which can be spent as initial investment

Light, thermal and noise properties:

Light properties:

  • LT (light transmission) - the percentage of light that goes through the glass.
  • LR (light reflection) - the percentage of light that gets reflected by the outer glass pane and does not get let into the room.
  • UVT (ultraviolet transmission) - percentage of ultra-violet radiation transmitted.

Energy properties:

  • EA (energy absorption) - percentage of solar energy absorbed by the glass sheet or sheets.
  • ER (energy reflection) - percentage of solar energy flux reflected by the glass.
  • SF (solar factor) - ratio of total solar energy flux entering through the glass to the incident solar energy. The total energy is the sum of the incoming solar energy by direct transmission (DET), and the energy reradiated by the glass to the inside atmosphere after being absorbed by the glass (EA).
  • U [W/m2.K] - U-value (Europe) Heat-transfer coefficient The heat-transfer coefficient (or U-value) is the amount of heat in watts transmitted per hour through 1 m2 of wall (glass) with a difference of 1 Kelvin Degrees between the inside and the outside (W/m2.oK).

Noise reduction:

  • Rw dB - noise reduction in decibels.
    It varies around 25 for conventional single glass glazing, 30 for convention insulating glass units with glass thickness of min. 200mm., 35 for insulating glass units with thicker glass, 40-45 for tripple glazed insulating glass units and above 50 for unconventional structures.
  • Noise suppression in % - additional parameter regarding noise reduction qualities.

© 2023 www.bulit-glass.bg