[Greenbuilding] please rant: thar she blows

[Corwyn]

On Apr 10, 2007, at 10:28, Nick Pine wrote:

>>>> I would love to see the analysis that came up with that number.
>
> A low-mass (eg SIP) house with 4 rooms with doors and insulated
> interior walls might have a 75% savings, if only one room at a time
> is heated... What's the savings in this case (viewed in a fixed font)?

Significantly less than 75%.  First, all those other rooms can't be 
outside temperature or 1) your pipes will freeze, and 2) they won't 
heat up fast enough when you enter them.  Second, the interior walls 
will need to be insulated to the same level as outside walls (including 
whatever vapor issues you have).  Third, low mass is not no mass.  
everything in the room is going to heat up and then cool down again, 
and since it is in a room isolated from all the others it will be 
losing most of that heat to the outside rather than the other rooms of 
the house.

I stick by my finding of a maximum of 37% savings, BEFORE heating the 
individuals. (at least for my climate).  You also need to consider the 
embodied energy in the additional insulation, the power used by the 
control system, etc.

Thank You Kindly,

Corwyn
-- 
Corwyn
Kermit didn't know the half of it...
http://www.greenfret.com/
corwyn at greenfret.com