[Greenbuilding] windows better than walls (was Vacuum insulation panels...)

JOHN SALMEN terrain at shaw.ca
Fri Nov 4 13:41:36 PDT 2011


I keep thinking of a great comment from William Morris on the advent of
large rolled glass windows. Something to the effect that if you want to feel
like you are outside you should go outside.

-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of
stephen at thermotechfiberglass.com
Sent: November-04-11 1:25 PM
To: jfstraube at gmail.com; Green Building
Subject: Re: [Greenbuilding] windows better than walls (was Vacuum
insulation panels...)


To be clear, I agree w/ John's inference that just because you can buy 
a heating climate window that is more energy efficient than the wall 
around it, does not mean that should build a whole wall of them.

It is in fact a rather silly idea - for all of the reasons John 
suggests. I would also like to add cost to his list.

In a heating climate, i think you need net gain windows to build a net 
zero house.

What you don't need is a wall full of them.

Stephen


On Thu, 3 Nov 2011 16:48:20 +0000, John Straube wrote:
> On Robs interesting comment on windows.
>
> As part of our Decathalon project 2 yrs ago, we designed an all glass
> wall (cause the architects wanted this) and tried to get it to use
> less than a super insulated wall.
> After much hourly modeling for the Toronto climate we found that
> 1. Solar gain through high percentage of high performance windows
> will cook the interior of homes, dangerously so. Thus exterior 
> shading
> is critical. If someone is not home all the time, a sunny day in 
> March
> can melt plastic without so automatic shading or venting.
> 2. With automatic shading on the exterior, a window area of 100
> percent requires an R10 window to equal the performance of an
> insulated wall. If the window area is less, the window R-value
> required is less.
> We built the best we could: wood frame, fiberglass clips, quad glazed
> Krypton filled units 10' tall and 4' wide. This got us to a bit over
> R8 with edge losses and frame losses! My MASc student could not 
> figure
> out how to get to R10.
>
> Sent wirelessly from my BlackBerry device on the Bell network.
>
> -----Original Message-----
> From: RT <archilogic at yahoo.ca>
> Sender: greenbuilding-bounces at lists.bioenergylists.org
> Date: Thu, 03 Nov 2011 12:29:09
> To: Green Building<greenbuilding at lists.bioenergylists.org>
> Reply-To: archilogic at chaffyahoo.ca,
> 	Green Building <greenbuilding at lists.bioenergylists.org>
> Subject: Re: [Greenbuilding] Vacuum insulation panels...
>
> On Wed, 02 Nov 2011 10:40:37 -0400, Gordon Howell -- Howell Mayhew
> Engineering <ghowell at hme.ca> wrote:
>
>> a Korean company that is now offering
>> vacuum insulation panels (VIPs)
>
>> a VIP encapsulated in a thin layer of EPS
>
> Notwithstanding the issues of longevity and ability to accommodate 
> people
> with sharp and pointy objects, I did wonder how much of an 
> improvement the
> vaccuum (ie not including the EPS skins) provided over a simple 
> reflective
> still air space (or couple of), also sandwiched between layers of
> insulation ?
>
> My *guess* is "Not enough to justify the incremental 3x cost and
> questionable longevity of the vaccuum seal."
>
> I would also venture that if a VIP is an absolute "must-have" on a
> shopping list of nifty building envelope items, then superwindows 
> might be
> a better way to go since some would have the capacity to be net 
> energy
> gainers, even when placed on a non-equator-facing orientation.
>
> Unlike the Korean VIPs, Super-IGUs would provide the homeowners with 
> the
> ability to visually assess the integrity of the vaccuum seal and 
> allow for
> reasonably easy replacement of the failed units and subsequent re-use 
> of
> the "panel" materials.
>
> Seeing Stephen Thwaites here amongst us again reminded me of the 
> novelty
> superwindow his company made sometime in the last millennium just for 
> fun,
> claimed to outperform a conventional 2x6 stud wall.
>
> Although I know nothing about that window, my guess is that it was 
> well
> under 150 mm thick (through the glazing), probably thinner than an
> equivalent R-value Korean VIP.
>
> As my brother's high school pool room buddies used to say after 
> pulling
> off a pretty good shot "Not tea bag ! Eh ?"
>
> --
> === * ===
> Rob Tom
> Kanata, Ontario, Canada
>
> < A r c h i L o g i c  at  Y a h o o  dot  c a  >
> (manually winnow the chaff from my edress if you hit "reply")
>
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