[Greenbuilding] Passive House Overheating

[Corwyn]

On 8/16/2012 12:17 PM, jfstraube1 at bell.blackberry.net wrote:
> This whole thread started by mean pointing out that an obsession with hitting an arbitrary heating number can result in overheating and high SHGC are part of the problem.
> Without asking people to make many changes in their comfort and their lifestyle superinsulated homes can make very large reductions (eg 3 to 5 times less energy that code built) in their energy use.
> Yes one may be able to get to 5.5 times less energy by asking people to accept higher temperatures, operate shades or pay 10K for automatic shades.
> My argument is that there are small benefits to some of these approaches and high social or economic costs.
> Low SHGC windows, tighter comfort, giving up the arbitrary 15 kwh/m2 heating limit while still accepting the 120 kWh primary energy number hardly seems like that flawed of a way forward.

I did not say:
1) People should accept higher temperatures
2) Operate Shades
3) Pay 10k for automatic shades
4) Make ANY changes in their comfort level

I am not sure what you are arguing against.

My points:

1) Low SHGC windows in the house under discussion would *increase* total 
energy usage, at the *same* comfort level.  I never recommend 
compromising comfort levels; I often recommend improving them.

If he replaced his high SGHC windows with ones with s SHGC of 0.23 or 
lower, the windows would no longer be energy positive, and he would be 
better off with a wall instead (which would do nothing to cause 
overheating).  In general, from a heating/cooling standpoint, having 
windows which aren't energy positive is counter-productive, especially 
if we expect that people can't be bothered to open them.  (There are, of 
course, other valid reasons for having windows.)

2) The status quo is not sustainable.  Attaining something sustainable 
might require a live style realignment.  Not attaining something 
sustainable will definitely require a new life style.

3)(new) I agree that the arbitrary heating limit might not be ideal. 
For a builder like Chris Corson, it really isn't, when he is renovating, 
and hitting the limit is impossible, he gets as close as he can.  When 
he is building new, he sees how far *past* it he can go.  For other 
builders, having that goal actually gets them to go out of their way to 
improve heating efficiency; without the goal they would not have any 
incentive.  For yet others, it might be a spot where they say 'eh, good 
enough', when without it, they would have gone further.  My guess would 
be that most builders around here fall into category 2, YMMV.

A total energy limit does not accomplish quite the same thing, in that 
it is so dependent on changeable occupant choices.


Thank You Kindly,

Corwyn
Topher Belknap

-- 
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
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topher at greenfret.com
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