Big Green: Insulating Exterior Masonry Chimneys

[Dean Sherwin]

David
Interesting question, but first let me be a doubting Thomas, and ask, 
how would insulating a chimney improve building efficiency since the 
heat is all headed out?  It's true that keeping flue gases warm all 
the way up may improve draw somewhat.  It's also true that a warm 
flue makes lighting a fire without it smoking easier;  but this is if 
fires are lit and allowed to go out daily.  after a day or so your 
chimney will have cooled down anyway.
Typically a main reason for the faster deterioration of pointing etc 
on brick chimneys is because of the acids that come out of the flue 
top and are washed back down by rain.  So detailing the top of a 
(traditional brick) chimney is important, and the design of the cowl 
or chimney pot helps draw out the smoke.  For the reason of having 
less condensation of acids, the insulation could be 
beneficial.  Whatever method you choose, I suggest a good stainless 
steel cover  that covers the top of the insulation system (as well of 
course the chimney top and is flashed to the cowl) and extends 
slightly beyond with a drip edge.


At 04:18 PM 6/11/2009, sagefarm at comcast.net wrote:

>Dear Colleagues:
>
>Does anyone have any experience either recommending, or evaluating, 
>the insulating of exterior masonry chimneys.
>
>In theory, this should make the structure significantly more energy 
>efficient, as well as a lot easier to get a fire started in,
>
>but does anyone have any experience in this area?
>
>Sincerely,
>
>David W. Bearg, PE, CIH
>
>Life Energy Associates
>www.LifeEnergyAssoc.com
>20 Darton Street
>Concord, MA 01742
>978-369-5680
>
>----- Original Message -----
>From: "Mark Piepkorn" <mark at buildinggreen.com>
>To: biggreen at lists.biggreen.org
>Sent: Friday, June 5, 2009 5:35:16 PM GMT -05:00 US/Canada Eastern
>Subject: Big Green: Natural (en)Light(en)ing
>
>In response to a recent Environmental Building News feature story
>about the inefficiencies of building-integrated wind turbines comes
>this subtly hilarious examination of the efficiencies of
>building-integrated prayer wheels.
>
>http://www.buildinggreen.com/live/index.cfm/2009/6/4/BuildingIntegrated-Prayer-Wheels
>
>(This post is only off-topic if you don't follow the links back to
>the original article.)
>
>
>Mark
>
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Dean Sherwin CPE
Certified Professional Estimator
LEED Accredited Professional
CONSTRUCTION COST MANAGEMENT
3, Cherry Street
PO Box 11
Media, PA 19063-0011
(610)892 8860
fax (610) 892 7862
costman at verizon.net  
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