Saving Concrete

Peter Amerongen is fond of saying "concrete is one of the most energy intensive things we do".  Or something to that effect.  By "we", he means humanity, and he's right:

Cement is the principal ingredient in concrete[, and] cement manufacturing accounts for approximately 7% to 8% of CO2 globally, and approximately 1.8% of CO2 emissions in Canada" (source).

The concrete used in the  Millcreek NetZero Home (MCNZH) will be composed of about 50% fly ash (a waste material from coal-fired power plants) to minimize the use of cement. We're still using too much concrete, but since my family is spending its life savings on this house, we weren't willing to experiment when deciding how to add mass to the home to store solar heat.

Still, reducing our use of concrete is a priority, and were doing it in a couple of ways:

  • We're not building a garage. Since we're car free, and since our building site already has a (very old) garage on it, we decided to not build a new one in order to save materials, energy, and money.
  • We're seeking non-concrete options for sidewalks, pathways, and other landscaping.
  • We're reusing concrete blocks and the broken up sidewalks that will result from the demolition of the existing home to build paths and sidewalks.

Old sidewalk blocks have been removed and stored so they don't get broken during demolition and excavation

The old garage on the site - we like it and we're keeping it!

The greening of concrete is an area that needs desperate attention - it's a brilliant building material that is used in almost every building we put up. However, it's an environmental nightmare. That's why concrete houses are not at all green (contrary to claims made by the likes of Con Boland), and we should strive to reduce its use as much as possible.

In our next house (ha ha), maybe we'll figure out a better way to store solar heat than in concrete floors. There's a guy who's building in the Garneau neighbourhood who's storing it in pop bottles filled with water. Now that's a benign source of solar mass.

In the meantime, we'll do our best to minimize our use, even if it just means reusing old concrete blocks and not tearing down the second building on our building site.


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How about using the rocks from farmers field who would really like to get rid of them to use as mass heat storage under floors in basement, as dry wells, as fill around basements for drainage to weeping tiles. How about considering hollowcore concrete slabs for floors to add mass to all floors, the hollows for running electrical, communication and piping or just air flow from a hot area to cold areas, adds structural strength, etc. How about earth/rock berms on the north side. Just a few thoughts for you. I come from Finland where they have been using 4-pane windows for decades, smaller windows and shared hot water systems for adjoining homes and using time-of-day metering for electrical use for heating about 5000litre tanks by electricity or wood which ever is most economical (this up near the Arctic Circle in northern Finland. In Tampere they recycling the power plants hot water through homes through pipes in channels under the sidewalks (also cables for electricity, communications etc) which also help clear the sidewalks of snow (which they get a lot of). Better stop now and get to work. One more thought I've converted a lot of my windows to 4 pane by using recycle windows/glass and approaching the same heat loss as the walls. Now I'm done, bye. Veikko

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