Home Old double glazing vs new

Side-by-side comparison of old double glazing vs new

On this page, you will find a side-by-side comparison table of old double-glazing vs new double-glazed units.

Our comparison focuses on glazing rather than the whole windows, as glazing is the most crucial window feature to compare when it comes to energy efficiency and heat loss. Double glazing also contributes to the window’s energy rating and insulation efficiency.

Our company specializes in double-glazing existing sash windows. We know a great deal about a wide range of insulated glazing and which glazing solution is suitable for retrofitting Listed and non-listed properties.

Which double glazing should we consider old?

Double-glazing first started appearing on UK properties in the 1970s, revolutionising how energy was conserved in homes.

The insulation created by a double-glazed window prevents heat from escaping, meaning that the household can maintain internal warmth without the need to crank up central heating.

Any double-glazing installed between 1970 and 2005-2010 is considered ‘old’, as it will be significantly less efficient than newer glazing, which has been designed to meet modern energy ratings.

What is the main difference between old and new double-glazing units?

The first principal difference between old and new double-glazing units is insulation, which fills the cavity between two glass panes.

The second difference is the warm spacer bar, perimeter seal, and secondary sealant. Almost all modern double-glazing units are gas-insulated, and manufacturers work hard to keep the gas in to extend their service life.

The third difference is in the glass panes. New double-glazing panes can be laminated during manufacturing, blocking UV and improving solar control.

Unless the insulated glazing is triple glazing or has acoustic glass, the window’s glazing has similar sound insulation properties to old double glazing blocking external noise.

difference between old and new double-glazing units

To compare window glazing options, please select the type of glazing you want to compare.

You can compare up to three glazing options simultaneously on desktop and up to two on mobile devices.

Old double glazing vs New

Suppose you are considering replacing your windows, secondary glazing, or retrofitting single glazing to reduce heating bills. It can be difficult to understand which glazing option would work best for your project.

To help make the decision easier, here is some key comparison information that might be useful.

Suitable for retrofitting

Warranty & Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

15+

Estimated Lifespan

Warranty

20+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

15+

Estimated Lifespan

Warranty

20+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

25+

Estimated Lifespan

Warranty

15+

Estimated Lifespan

Warranty

20+

Estimated Lifespan

Warranty

Energy efficiency

0.7

U-Value W/m2.k

5.8

U-Value W/m2.k

0.69

U-Value W/m2.k

1.1

U-Value W/m2.k

0.48

U-Value W/m2.k

1.9

U-Value W/m2.k

1.2

U-Value W/m2.k

2.6

U-Value W/m2.k

0.7

U-Value W/m2.k

5.8

U-Value W/m2.k

0.69

U-Value W/m2.k

1.1

U-Value W/m2.k

0.48

U-Value W/m2.k

1.9

U-Value W/m2.k

1.2

U-Value W/m2.k

2.6

U-Value W/m2.k

0.7

U-Value W/m2.k

5.8

U-Value W/m2.k

0.69

U-Value W/m2.k

1.1

U-Value W/m2.k

0.48

U-Value W/m2.k

1.9

U-Value W/m2.k

1.2

U-Value W/m2.k

2.6

U-Value W/m2.k

Vacuum port / Plugs

Getters

Yes, along unit edge

Yes, circle in corner

Yes, along unit edge

Yes, circle in corner

Yes, along unit edge

Yes, circle in corner

Microspacers

At 20mm centres

At 70mm centres

At 20mm centres

At 70mm centres

At 20mm centres

At 70mm centres

Thickness

7.7 mm

Thickness

3-5 mm

Thickness

6.2 mm

Thickness

8.3 mm

Thickness

12 mm

Thickness

24 mm

Thickness

7.7 mm

Thickness

3-5 mm

Thickness

6.2 mm

Thickness

8.3 mm

Thickness

12 mm

Thickness

24 mm

Thickness

7.7 mm

Thickness

3-5 mm

Thickness

6.2 mm

Thickness

8.3 mm

Thickness

12 mm

Thickness

24 mm

Thickness

Unit Make Up

4 – 0.7 – 3

4 -12 – 4 -12 – 4

3 – 0.2 – 3

4 – 0.3 – 4

4 – 4 – 4

4 -16 – 4

4 – 0.7 – 3

4 -12 – 4 -12 – 4

3 – 0.2 – 3

4 – 0.3 – 4

4 – 4 – 4

4 -16 – 4

4 – 0.7 – 3

4 -12 – 4 -12 – 4

3 – 0.2 – 3

4 – 0.3 – 4

4 – 4 – 4

4 -16 – 4

Cavity thickness

0.7 mm

24 mm

0.2 mm

0.3 mm

4 mm

16 mm

0.7 mm

24 mm

0.2 mm

0.3 mm

4 mm

16 mm

0.7 mm

24 mm

0.2 mm

0.3 mm

4 mm

16 mm

Insulation

Vacuuum

Argon gas

Vacuuum

Krypton gas

Argon gas

Air

Vacuuum

Argon gas

Vacuuum

Krypton gas

Argon gas

Air

Vacuuum

Argon gas

Vacuuum

Krypton gas

Argon gas

Air

Visible Light Transmittance

79%

64%

78%

79-85%

81%

81%

79%

64%

78%

79-85%

81%

81%

79%

64%

78%

79-85%

81%

81%

Manufacture Location

Belgium 🇧🇪

UK 🇬🇧

Japan 🇯🇵

China 🇨🇳

UK 🇬🇧

Belgium 🇧🇪

UK 🇬🇧

Japan 🇯🇵

China 🇨🇳

UK 🇬🇧

Belgium 🇧🇪

UK 🇬🇧

Japan 🇯🇵

China 🇨🇳

UK 🇬🇧

Lead-timed

6-8 weeks

4-6 weeks

16 weeks

10 weeks

2-4 weeks

6-8 weeks

4-6 weeks

16 weeks

10 weeks

2-4 weeks

6-8 weeks

4-6 weeks

16 weeks

10 weeks

2-4 weeks