Subject: Re: Double low-e glass with inert gas filling

From: [email-masked] (Duncan Noble)
Date: Fri, 10 May 1996 16:42:39 -0400

In article <[email-masked]>, Mother Jones <[email-masked]> wrote:

> We are about to replace a bunch of single pane windows with double pane 
> window units. We want noise reduction, and in at least some of the windows 
> we want UV filtration because we have fading. These windows are on the south 
> side of the house where the sun is quite bright, and that part of the house 
> gets quite hot in summer. (However, we live in coastal Southern California, 
> so extreme heat and cold are not really a major issue, compared to other 
> climates.)
> 
> We know that dual-glazing will give us noise reduction, along with 
> temperature insulation, and we like that. For the fading and heat problem we 
> were planning to get dual-low e glass also, but we've heard that the low-e 
> coatings that have been around for a while are now showing that they don't 
> actually last. Does anyone have any info about this? Should we go for low-e? 
> Why or why not?
> 
> We'd also like to know about the argon and other inert gas fillings that are 
> often used in dual low-e. How worthwhile is this feature? Is dual low-e 
> worthwhile without inert gas filling?

You may want to read some of the information published by the DOE on this
topic at:

http://www.nrel.gov/documents/erec_fact_sheets/erec.html

Keep in mind that the low-e is meant to block heat radiation ("southern"
low-e blocks heat radiation from entering your house; "northern" low-e
blocks heat radiation from leaving your house.)

Argon is the only cost-effective inert gas for most applications (as far
as I know). Argon increases the insulation value of your window, against
heat loss or gain by conduction.

To answer your question properly, you would have to consider how much
energy/$ you spend annually heating and/or cooling your house. If the
amount is small, you  won't be saving much in the way of $, but you may
make your house more comfortable. Dual low-e may be overkill, but single
low-e with with argon fill will only add about 5-8% to the cost of a good
quality window, not counting installation costs.

> 
> For the windows that are not exposed to direct sun, is there any reason to 
> have low-e panes -- with or without inert gas?

I'm not sure about that for Southern California. Up here in the north, the
answer would be yes, since the low-e and argon fill block heat loss from
the house, which is more an issue on the north side of the house. 
> 
> Gila Jones     -----     [email-masked]

-- 
Duncan Noble, Noble Consulting
Ottawa, Ontario, Canada