Real data on the magic of Low E coatings for cold climates?

I bet most of you are familiar with the claims of the window industry marketing a Low-E coating as a Cure-All for any house, any climate and any window, no matter what direction it faces. 

You have likely seen the heat lamp test that make people think that their products have some serious insulating properties. 

While I am not doubting on the effectiveness of Low E coating for cooling-dominating climates (installed on the windows that the Sun shines through) I have real doubts on how effective it is for cold climates.

There is a claim that a HUGE portion of the heat that escapes through a window does so in the form of radiant heat and Low E coating reduces it. 

I am sure Low E is very effective for reducing radiant heat loss. I am very skeptical on the size of the portion of the escaping heat being radiant.

And then I am also thinking that all the rejected solar gain in the winter must be greater than the amount of heat we trapped inside. (just because Sun's surface is about 10 000F vs 68F for the surface of the objects inside a home)

I bet many of us would benefit from reputable data on the portion of the heat that escapes through a window in the form of radiation.

Opinions, thoughts and facts appreciated.

Views: 245

Reply to This

Replies to This Discussion

Low E helps in summer when the sun is at a different angle.  The UV rays reflect differently then the winter, when the sun is lower.  Heat is better reflected in summer versus winter due to the angle of the sun during the seasons.  The solar gain in winter comes from the sun's angle allowing more UV/Heat in this way as well, since it is not reflected by the Low E as easily.  As far as Low E helping during cold months, the radiant heat form interior lighting gets a slight gain in heat by reflecting heat from the windows into the home.  Not in dangerous amounts, just enough to help a little in comparison to non Low E coated windows.  Interesting stuff.    There is a lot of information, sometimes too much for the consumer.  It is always best to do research from homeowner testimonials as well.  Great post by the way

-TONY

Denver Window Replacement

So much of this depends on the size and orientation of the window.  North-facing picture windows are more common than one would suspect, and with our high altitude dark nights, you can really feel the "suck" from the night sky.

New Mexico has adapted the IECC to be more "passive solar friendly."

http://www.emnrd.state.nm.us/ECMD/FORMS/SolarWorksheet.xlt makes it relatively simple for a building official sign off on a design.

RSS

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Kurt Shafer replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Reading the Invisco description you will find that it is designed to be surrounded by cellulose to…"
16 hours ago
Glen Gallo replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Kurt, I think cost of operation is always a factor but I am not sure I would leave it just cfm.…"
17 hours ago

Paul DelVaglio just added their location.
(via Member Map)

18 hours ago
Paul DelVaglio posted a photo
19 hours ago
reflintorm replied to Jamie Kaye's discussion Flickering LED lights
"I think, Better to replace the dimmer switch if it is not recovered then once go through the…"
22 hours ago
Kurt Shafer replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Glen,  You are the first person who has ever told me they prefer lower CFM. What you left out…"
yesterday
Glen Gallo replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Tamarack has lower CFM than typical fans and has a insulated lid that automatically closes when fan…"
yesterday
Tom Conlon's discussion was featured

Whole House Fans - Love 'Em or Not?

I just searched this forum for "Whole House Fan", but I didn't find much about them (except …See More
yesterday
Tom White shared Brandon Walton's blog post on Twitter
yesterday
Brandon Walton's blog post was featured

12 Things Every Home Performance Contractor Should Have on Their Work Truck

Every home is unique and differs from the last. It would be a perfect world (from a project…See More
yesterday
Griffin Hagle replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
yesterday
Griffin Hagle replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Kurt, Whoops, looks like I got my links mixed up. Thanks for pointing that out. Here's the…"
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service