Glass Windows and Doors

U-value and SHGC

Glass is characterized based on two figures:

U-value — amount of heat loss per degree temperature difference between inside and outside per square meter. It is main figure when it comes to energy efficiency. The less the U-value is the better thermal performance glass has.

SHGC — Solar Heat Gain Coefficient — this is amount of solar radiation that passes through the window. The lower it is the better it is in summer. However, in winter we need solar heat radiation to bring some warmth into the house through the window.

There are other values like UV — percentage of UV-rays that get through the window, transparency etc., but they are usually secondary.

Rw is another noise factor measured in Db and we are explaining everything about glass and noise here.

Single, double or triple glazed?

It is not a secret that single glazing is a term of the past. But let’s see why double glazing makes such a difference and compare whether jump to triple glazing will bring worthy effects.

Let’s have a look at basic 4 mm glass in single, double and triple glazing option with 12 mm gap used.

We will further show how we can achieve more efficient ways in double glazing that supersede triple glazed units in cost and efficiency.

 

 Glazing Single glazed clear Double glazed clear Triple glazed clear
 

 

Glass composition

  

 

4 mm

  

 

4 mm / 12 argon / 4 mm

  

 

4 mm / 12 argon / 4 mm / 12 argon / 4 mm
 

 

U-value

  

 

5.8

  

 

2.7

  

 

1.8

Calculations were done using Pilkington Spectrum Software spectrum.pilkington.com.

Safety glass – toughened and laminated

Safety glass usually relates to glass products that are safe for human impact if broken. There are two options for safety glass — toughened and laminated.

 

 

 

 

 

 

 

 

Toughened glass — glass that has been tempered. After this procedure glass becomes stronger and if broken would collapse in a lot of little pieces. This process does not change any other properties of glass performance.

Laminated glass — this glass consists of two layers of glass with film in the middle. Film can be transparent of in different colour (for translucent glass options). When broken small glass pieces stay connected to the film and therefore glass does not collapse and is therefore safe. Laminated glass has further benefits to it:

Enhanced security

even if the glass is broken it is still hard to walk through such glass. Therefore house stays secure even if glass panel has collapsed

Additional noise performance

film that is used in laminated glass works as a noise barrier and therefore laminated glass will work better with noise than float glass of corresponding thickness

UV protection

layer of film in laminated glass reduces amount of UV rays for up to 99% what is a great benefit if you would like to protect your floors and curtains from fading

Low-Energy Glass

Low-energy glass is a special glass product designed to further increase energy efficiency.

Low-E is a special coating applied to the surface of the glass that works like infrared mirror reflecting the heat or cold back to the street.