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Editor's Notepad

Editor's Notepad

Major Thermal Bypasses: Energy-Wasting Holes in Your House

comments (4) January 29th, 2013 in Blogs
Why worry about the tiny cracks around your windows when there are huge holes in your attic floor?Click To Enlarge

Why worry about the tiny cracks around your windows when there are huge holes in your attic floor?

"Major thermal bypasses" is building-geek speak for holes in your house - holes through which you are losing an abnormal amount of heat. More formally, they are areas in standard construction where flaws in the building enclosure allow air to escape, bypassing the thermal control layer.

Thermal bypasses: the what and where

The building envelope includes those elements of the building (the floor, walls, and roofs) which separate the comfortable interior from the potentially uncomfortable exterior.

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A huge part of an energy audit is inspecting the building envelope for problems. And thankfully, as builders have standardized their building practices, they've been considerate enough to standardize how and where they make giant holes in the building envelope. Thanks, guys!

Thermal bypasses and the home buyer's dilemma

As I mentioned, thermal bypasses are inadvertent holes in the building envelope. If one were to conceive of a perfectly insulated and airtight house (with an appropriate level of fresh ventilation air … no suffocating), it would be very simple. Make it like a box.

Wait, you want to get inside?! OK, we'll add a door. And you want to see the ocean view you paid an extra $100K for? Well, they have a really lousy R-value compared to walls, but I suppose we can add a few windows. And a cathedral ceiling and recessed lights and a hot tub and a finished room over the garage and a zero-clearance fireplace and a giant hole in the wall for fresh air. (Wait a minute...)

You see where this is heading. Home buyers have wants and needs, and they are most often at cross purposes with the aim of having an easily defined building envelope. And the harder the building envelope is to define, the harder it is to keep the uncomfortable outside away from the comfy interior.

List of thermal bypass locations

When developing their housing certifications, Energy Star put together their list of common thermal bypasses. Thankfully, the good folks at the Department of Energy have collected this info in one place: the Energy Star thermal bypass list:

And the hits just keep on coming. Check out Energy Star's list of thermal bypasses and take a look around your house. Fixing one of these issues can be a real heat saver and money saver.

Erik North, the owner of Free Energy Maine, is an energy auditor and home performance specialist in Westbrook, Maine. He is also the author of the Energy Auditing Blog.

posted in: Blogs, energy efficiency, weatherizing
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Comments (4)

Edward1234 Edward1234 writes: Guys, you might be interested in checking out fine luxury homes by Brejnik Fine Homes ( They build fine luxury houses. Brejnik team consists of qualified and trusted: Architects, Interior Designers, Appraisers / Lenders, Trades & Suppliers, Geo-technical engineers, Structural Engineers, Arborists, Landscape Architects, Pool & Water Feature Specialists.
Posted: 2:37 pm on May 14th

AdCherry AdCherry writes: In Australia we put warm cartons of beer in these voids during winter and cold cartons during summer. The statistical data is not over whelming and you do need an extended line of credit at the bottle shop but in this modern age of many global beers the practice does help to determine which beer tastes better at which temperature.
Thermal Performance Assessor
Perth Western Australia.
Posted: 12:37 am on February 9th

jiment jiment writes: Thermal bypass yes... but more importantly a fire hazard as all chimneys should be fireblocked at every floor level...:)
Posted: 9:26 am on February 4th

bill117 bill117 writes: Get the cat out of the hole. ;)
Posted: 8:08 am on February 4th

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