radiant barrier on block homes, attic fans, pink panther, Arizona Public Service, Salt River Project


Home Online Store   Contact

Sweater Effect

Hot roof beaming infrared heat into the insulation.  Image captured in Phoenix AZ at 9am

Copyright 1994 Horizon Energy Systems Inc.
Twenty years of building science and designing effective Climate Specifictm products was the result of documenting how heat moves into and out of buildings using an infrared camera. 

Homes built in sunny climates need different methods of controlling infrared heat vs convective heat losses which need addressing in cold climates.  Basic laws of thermodynamics dictate "heat always moves from a higher temperature to a lower temperature".  But how the heat moves is critical to understand when designing new or retrofitting existing structures.  First question: "Is heat loss or heat gain the main design criteria?". 

If it's sub zero weather and high winds you need to protect against then an exterior air barrier like Tyvek, sufficient insulation to resist convective losses and a tight building should be high on your list of means and methods to keep energy consumption in check.  However, if the building is baking under the sun all day and has a hot roof which is radiating infrared heat down into the ceiling then a different plan should be considered using different products.  A plan of reflecting the unwanted infrared heat with a proven radiant barrier and then a means to exhaust the waste heat using natural or powered venting.  Since natural venting sometimes falls short of adequate ventilation we've found installing a quality fan with sealed ball bearings and an accurate thermostat an effective method to achive this. 

I call using insulation in a hot climate the "Sweater Effect" which would be akin to putting on a sweater to increase comfort before going outside to do yard work in the sun.  Doesn't sound too logical does it?  One must ask why our national building codes demand we do exactly this in homes in hot climates.  We have homes being built in all types of climates: humid tropical, desert and the frozen Midwest and North yet the national building code requires the same products in all buildings regardless of what environment they are being built in.  This had to change. 

Here's a recent article on my discoveries of the "Sweater Effect" click here.

Related links and stories: 
ABC Channel 15 News story 11/05/2009: 
Click here
Republic Newspaper article 3/11/2012:      Click here
Maricopa County Home Show radio blog:  Click here


The term "Sweater Effect" is a trademark of Horizon Energy Systems and is not to be used for reproduction without permission.


Web page design and maintained by B Rad Design Group
Copyright 1997-2017 all images, text and HTML copyrighted by Horizon Energy Systems.
All rights reserved and violators will be prosecuted.

Information in this document is subject to change without notice.

Other products and companies referred to herein are trademarks or registered
of their respective companies or mark holders.