Is Low-E Glass Worth The Money?

What is Low-E Glass?

It is a normal glass that has an extremely thin, transparent coating applied. (Single glazed low-E glass is peculiar to Australia)

The coating reflects part of the ultraviolet, and infrared light, while allowing most of the visible light through.

In Australia the main advantage is that it helps cut down the amount of summer direct sunlight coming through the windows and overheating rooms.

A secondary benefit is it will reflect some of the  heat back into a room in winter reducing the radiant heat loss through the glass.

A disadvantage is that the coating may be damaged by cleaning.

Suitable For All Orientations?

A Low-E Glass reduces solar gain in winter as well as summer.

North Facing

I definitely wouldn’t recommended Low-E glass or Reflective Films for sun control for windows where you expect to get the advantage of heat from the sun in Winter. That is North facing windows . . . proper shading will be a better solution.

East or West Facing

Low-E glass will be a better performer for East and West Windows although I would be going for a highly reflective film myself.

South Facing

Some practical issues are; is difficult to clean, can spontaneous fracture from thermal shock, and its performance won’t be close to double glazing.

Typical Performance

Total Solar Energy Rejected 49%
(Higher % = less heat in summer)

Glare Reduction 22%
(Higher % = less glare)

Ultraviolet Rejection 99%
(Higher % = less harmful UV rays)

Visible Light Transmittance 70%
(Higher % = more light shining through)

Visible Light Reflectance (Interior) 4%
(Lower % = less reflective/clearer view)

To compare with plain glass windows check this link Energy Through The Windows


I am not convinced that the benefits of Low E Glass are worth the additional cost when other solutions are available such as:

Overall I feel Low E glass is more appropriate at complementing double glazing rather than replacing it.