[Greenbuilding] CF analysis of tearing down a house vs. renovation?

Matt Dirksen dirksengreen at gmail.com
Tue Jul 23 11:21:02 MDT 2013

And as far as I can tell, I've never seen an old house get torn down to be
replaced by the same size house. Usually, the builder tries to make the new
house as large as zoning will allow - likely tripling the original home

I just wonder if anyone has thought of a good analogy to describe the
embodied energy difference between renovation vs. new. For example, I have
some projects where we added a full second stories to houses, typically
ramblers. Given the efficiency improvements that were completed along the
way, I am very curious on their performance now.  But to compare that to
tearing down/building a new house of the same (new) size seems hard to
measurably quantify.
(fwiw, I just sent an email off to one of them asking about their past
year's gas/electric bills)

On Tue, Jul 23, 2013 at 11:51 AM, John Salmen <terrain at shaw.ca> wrote:

> 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
> 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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