Friday, December 11, 2009

So Much Confusion, So Little Time

Since the press release last week, publically announcing Redhook Green, there has been so many questions, comments, criticisms and confusion regarding the project that I thought I would devote a few posts to clearing up some of them.

There seems to be a general lack of clarity on the relationship between “Zero-Energy Building (ZEB)”, “Carbon-Neutral”, and “Sustainable” when it comes to construction as a whole and specifically as it relates to this project.  Each of these very important strategies are tools in helping the way we live fit more cohesively with the needs of others and our planet in general, but practicality needs to play a role as the various objectives are weighed and implemented.  For me they include feasibility, environmental impact, upfront cost, long term cost, availability and reliability.

There are three primary concerns relating to the energy consumption of Architecture:
1.  Energy to construct
2.  Energy to heat and maintain
3.  The total of both over the lifespan of the structure

From my simpleminded perspective, a net zero energy building is a great place to start.  It seemed to me if we could design a home that based on the nature of it’s construction, could consume significantly less electricity heating and cooling and then generate the power we needed using the sun and trade the rest for times we can’t, we would have to be a great start.  I like the fact that it’s reasonably easy to measure success here, if I sell ConEd as many kilowatts of electricity as I buy, then I am net zero energy.  Cool.  Right?

Next if you do a search on the web for a definition of “carbon-neutral”, in many cases it defaults to the ZEB definition and discusses renewable sources.   As I understand it, a building that is carbon-neutral uses no fossil fuels in its operation, creates no direct greenhouse gases, and, as a result, does not contribute to global warming. Also power drawn from the utility grid but it must be “clean,” produced by wind turbines, photovoltaic, or other renewable energy system. So, a building that is both Carbon Neutral and Net Zero Energy produces at least as much renewable energy as it uses each year.   But (big BUT) most definition neglects to discuss a very important use of energy that must be taken into consideration for a true carbon neutral structure.  That is embodied energy or as I mention above the energy to construct.



The Wikipedia defines “embodied energy (or emergy) is defined as the available energy that was used in the work of making a product. Embodied energy is an accounting methodology which aims to find the sum total of the energy necessary for an entire product lifecycle. This lifecycle includes raw material extraction, transport, manufacture, assembly, installation, disassembly, deconstruction and/or decomposition. “   Basically all the materials used in the house consume energy during manufacturing, delivery and installation on site.  Would you imagine that aluminum requires more energy than steel to be manufactured?  Or that recycled aluminum and steel use half of the energy to fabricate (just a few fun facts from a discussion with Jim)?  There is embodied energy in any processed product, from a drinking cup to a car. In embodied energy terms, buildings represent a huge, relatively long-duration energy investment.


Material

Unit

Energy Coefficient 
Mj per unit

Timber, rough

m3

848

Timber, air-dry, treated

m3

1,200

Timber Glulam

m3

4,500

Timber, kiln-dry, treated

m3

4,692

Timber, form work

m3

283

Plywood

m3

9,440

Building paper

m2

7.5

Gypsum board

m3

5,000

Glass

kg

31.5

Structural steel

kg

59

Aluminum

kg

145

Fiberglass

kg

150

Asphalt, strip shingle

m2

280


It seems to me that as the operating energy required for buildings declines, the embodied energy they represent becomes a more significant percentage of the total energy buildings use. In coming years more efforts will probably be directed toward measuring and reducing the amount of embodied energy in buildings.

So as you can see, this all gets very difficult to measure accurately. Measuring embodied energy is still in an early phase, but is very important.  But from my perspective for this project (right now) while I think that it is an important objective to build carbon-neutral buildings,  it might be less practical to get 100% there.  Remember ability to execute is everything!  So we move forward to reach our net zero goal while keeping our carbon footprint to a minimum via the materials we choose and construction methods employed (modular really helps).

If you want to learn more about what you can do, or how much embodied energy is used in different popular products visit, WattzOn.  It is an early stage online tool to quantify, track, compare and understand the total amount of energy needed to support all of the facets of your lifestyle with the goal of helping you find ways to reduce your personal power consumption.

More to come, including my thoughts on sustainability.

1 comment:

greenedoug@yahoo.com said...

Jay, great discussion. Your project is helping pull all of us along with your practical insights and honest reporting. Thanks for diving into all of this.