[Greenbuilding] future of framing

[John Salmen]

Alans comment about quality of spf got me thinking about how I keep slowly
changing my framing designs and where that might be leading - spf lumber
truly sucks right now and so do the forests. I was a reluctant convert to
engineered wood (19.2" floor assemblies) and now even sheathing. I am now
thinking of becoming a total convert with framing designs now for eng. studs
and wonder what comments people might have about using them. I've used them
for 20' high shear walls but that is about it.

Embodied energy seems equivalent, potentially better with less wastage.
Better quality/stength on 24" framing (stiffer envelope as well, less
movement allowing for better seals) and potential of reducing to 2x4 (even
for 2 story). 

Is cost really an issue?

-----Original Message-----
From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of John Salmen
Sent: July-23-13 8:51 AM
To: 'Green Building'
Subject: Re: [Greenbuilding] CF analysis of tearing down a house vs.
renovation?

Thanks for the article. 
What was interesting was the ranking of strategies.  High efficiency hvac
and insulation being the most effective for energy savings with air control
about 60% of those. What was also interesting is the comparison of pre-use
(construction) energy of the standard house versus a energy efficient house.
Standard being 6.1% of total energy and EE being 16%. Bad math would them
imply about a 6% increase in the carbon footprint of the new EE construction
(penalty of not utilizing existing energy expenditure??)

My answer from a design/build knee jerk perspective would be that renovation
is preferable for simple reasons. If the basic footprint and layout is
modest in size and has no huge design flaws any existing structure can be
insulated, made air tight and have a new energy system. Most significant
renovations take a building back to structure and the largest items in a
building in terms of embodied energy are typically structure (foundation
primarily). 

-----Original Message-----
From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of John Straube
Sent: July-23-13 5:42 AM
To: Green Building
Subject: Re: [Greenbuilding] CF analysis of tearing down a house vs.
renovation?

Love to hear the answer.  The difference in before to after energy use will
be a major determinant of the answer.  
Attached is a 1998 LCA of a house in Michigan.  They found 93% of the ENERGY
use over 50 years was due to operation, not embodied.  So materials and
energy during construction is not that important in normal houses.  The
question is, can you renovate to the same level of low energy performance?
If that performance is quite low, embodied energy will be quote a large
proportion.  If the building has a lifecycle of 75 or 100 years, then
operation becomes more important.
Complex question, but a worthy one!


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