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

[stephen at thermotechfiberglass.com]

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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