[Greenbuilding] Building performance modelling/evaluation/tweaking at the design stage (was Re: HVAC COPs)

[RT]

On Fri, 06 Feb 2009 06:45:22 -0500, noci <nochi at gmx.net> wrote:

> I think when you're not in a design/build position, you'll be (i.e. as  
> an architect) trying to spread out the work and responsibility, as your  
> profit margins (esp. for small-ish projects) are low enough already so  
> that you don't want the added headache (and liability) of promising  
> stuff you can neither guarantee nor ultimately have the time to do.


That may have been a valid argument years ago before the days when  
computers were an integral part of a practise but these days, not so much.

> I don't know about the US, but that's the way many folks operate here  
> over the pond (Germany=). I guess Bob is spot on in his diagnosis of how  
> i.e. big property developers work.

Here in Ottawa, one notes that the three largest home/condo  
builders/developers offer all or one of LEED, Energy Star or R-2000  
certified units in their product lines. Once one of them does it, it  
creates an incentive for everyone else in the same market get into the  
game or else they risk ending up becoming spectators.


> Speaking of tweaking, can anyone recommend good, practical and basic  
> literature on building energy performance & influence factors and how to  
> set up a calculation scheme?

I think that most literature (and software programs too for that matter)  
on the subject ultimately refers back to the ASHRAE Handbook of  
Fundamentals so that would probably be the best place to start if an  
understanding of what it is that one is doing and why one is doing it is  
desired.

There are no doubt, a plethora of books out there that have  
"re-interpretted" portions of it as a means of providing shortcuts of  
sorts but it always comes back to understanding the fundamentals, after  
which you can decide for yourself which shortcuts you want to take.

The value of any modelling/simulation exercise for the purposes of  
evaluating a proposed design is only going to be as accurate in predicting  
Real World performance as the accuracy of the input data.

That's not as daunting as it may sound.

ie Instead of inputs like "R-40" for "Walls", better accuracy would be a  
matter of identifying
major different "wall" areas (ie through cavity, through framing, ribbon  
joists, lintels etc)

or instead of "R-20" for "Foundation" identify above and below grade  
portions, middle portions of floor slabs/ 1 metre wide perimeter strips  
and their respective unique design temperature differences.

... and account for required ventilation air changes (something that is  
notably absent from the stuff Nick Pine often presents here.)

etc.





-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at  ChaffY a h o o  dot  C a >
(manually winnow the chaff from my edress in your reply)
__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com