[Greenbuilding] windows - flush vs recessed

[John O'Brien]

On Mon, Jan 30, 2012 at 8:47 AM, John Straube <jfstraube at gmail.com> wrote:
> Hiya George. Of course I know it is per unit length, as I quoted the units
> of W/mK
> So if I have a 5' by 4' window (1.5 x 1.2m) the additional heat loss of 0.01
> W/mK is 0.054 W/mK or in 0 F weather, 2 Watts. Lets say we allow us 0.03
> W/mK difference between the ideal location and the location preferred by the
> owner, or builder, or the window durability.  Now we are up to 6
> Watts/window. In a house with 12 windows, this is 72 Watts, at DESIGN
> CONDITIONS for Zone 5, and we have 2000 W flowing through the windows
> themselves.  The prescence of absence of overhangs and neighboring buildings
> will likely have this much ipact on heat loss.
> The real reason to worry about this stuff are the examples of when it is
> done horribly, and you have a 0.2 W/mK (which works out to 41W/window or
> 500W for 12 windows at design) detail and you start to risk condensation on
> the window edge.
>

http://passivehouse.us/passiveHouse/2010_Passive_House_Conference_Presentations,_November_5_files/2010%20Conference-Windows%20Roundtable-Bronwyn%20Barry.pdf

Where most of the 'window should be in the middle' has been coming
from. Anyone want to take a stab at her numbers?

She claims "By moving the windows to the center of the wall the Annual Heat
Demand was reduced by 22%."

Seems somewhat not insignificant.

J