THE GREEN STANDARD
by Dan Powell
To see a video of green construction click here!
The word has finally gotten out, green is in, green is hot, green is profitable and green is necessary!
So what is Green Construction Really? There are a lot of builders that are jumping on the band wagon proclaiming their conversions to "Green" that are using the same products they used when "not green". It reminds me of when so many food producers were claiming their products to be organic when the only organic product used was the diesel to power their tractors.
The Experts all agree that the GREEN standard includes three basic qualifications.
It is important to understand that energy efficiency alone DOES NOT qualify as green construction. Like the growing national deficit, high embodied energy and or unsustainability can not be repaid by low energy use, as the saying goes "you can't make up for loss with volume".
Products like brick, concrete, steel, and engineered lumber have a huge embodied energy and unless used sparingly bring the embodied energy so high that the deficit can never be repaid.
Another huge consideration is the reusability of a product at the end of its' lifespan. Steel has a very good reuse, as well as a recycle-ability but concrete does not. How about polystyrene? NOT, I suppose you can grind it up and mix it with cement, that is what Rastra is. then you can reinforce it with 3 or 4 tons of steel rebar then core it with 10 or 15 yds of concrete. all on a concrete slab and some with a concrete roof. all steel reinforced. NOT GREEN
I even have my doubts about strawbale, considering the cement stucco and concrete required for construction, By the way, straw has a pretty high embodied energy not to mention the damage to the land caused by removing it and not plowing it back into the soil. considering the bailing and the transportation then the use of membranes to keep it dry. It doesn't have any more lifespan than frame construction and there is a high use of timber frame or engineered lumber because straw bales are not load bearing. But it is energy efficient for a time and cheap. (it is my opinion that strawbale construction is NOT GREEN despite what many websites are claiming. It is true that strawbale construction can be green with the afore mentioned problems addressed however the sustainability is still in question because of the marginal lifespan of the structure.)
Papercrete? The utilization of reused newspaper with a minor amount of Portland and sand along with non-mortared stacking and vermin resistance make papercrete a viable alternative for the owner builder as a Green home. This a fairly labor intensive method although not as intensive as Adobe or Rammed Earth or used tire construction.
Used Tires? I included this method to underscore the importance of the owner-builder's contribution to the pantheon of Green construction practices. With the inclusion of Rammed Earth and or CEB interior walls and solar orientation and the exclusion of a concrete slab and foundation this is a wonderful system that has the potential of lasting hundreds of years, what better way to use a product that has performed its' lifespan as designed. This is a very labor intensive system though and not practical for the construction industry for that very reason. Remember: Labor intensive equates to very low end or very high end .
Logs. This is tough, most logs are processed to make them hollow or easier to fit. they burn real well but they have a fairly long lifespan, If people didn't build them in forests where they have easy access to big fires log homes would make more sense. Also if the designs utilized less ceiling height and less glass they may actually be energy efficient. There is also a reasonable argument for the un sustainability of Timber intensive homes so by this criteria NOT GREEN.
Adobe, anything more than 12" walls and preferably 14" or more can and with some design constraints should be GREEN. This is not always the case as the cost of adobe construction as well as the demands by designers are increasingly requiring the use of timber or lumber frame as well as MUCH engineered lumber and a high use of concrete. Again the embodied energy issue raises it's ugly head making a potentially good but high end (the reason for the problem) a problem instead of a solution.
Compressed Earth Block, Tougher than adobe, could last much longer and there are adobe buildings over 500 years old,
Pretty Green wouldn't you agree?
Dan L. Powell
Soils and Machine Education,
Earth Block Systems Design and Construction.