concrete floors

Concrete Floor Finish

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The best way that I can think of to add a large amount (20+ tonnes) of thermal mass to a solar home is by adding concrete floors. By doing this, one can get two uses, thermal storage and a finished floor,  out of the same investment. Furthermore, since the mass of a concrete floor is so spread out around the home, thereby giving it a large surface area with which to absorb and release heat, it really is the ideal thermal storage medium for a house with large solar gains.

So we added a 2.5 inch topcoat of concrete over the subfloor. In order to support the extra weight we had to add (recycled!) beams that run the length of the house (north to south).  After it was poured, the concrete was simply trowelled as a preliminary finish.

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pouring concrete floors over a regular subfloors (the walls had to be made 2.5 inches higher to compensate for the depth of the floors)

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a freshly trowelled concrete floor

For the final finish, we were partial to an acid-stain because we've seen some gorgeous stained finishes. Peter Amerongen convinced us to go for a water-based dye for environmental reasons. Man those green types can get in the way sometimes!

A talented man named Skip from Desco Coatings did the final finish. Peter describes the finish as such:
”We sealed the concrete with lithium silicate, then dyed it with water-based dye. The final coat was an epoxy coating, 2-part , 100% solids (so no offgassing because the soldis do not evaporate)."

The finished product is wonderful – a bit different at first, with an organic, charactery type of feel to it (yes, I just made up the word charactery).

The floor has been growing on me by the day.

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we love the saw cuts in this floor  read more... »

Observations (Part 01)

Mill Creek NetZero Home - living room

Mill Creek NetZero Home Living Room - finally some autumn sunshine!

Have you ever noticed that as soon as you move in to a solar house the sun stops shining? It’s been overcast since the beginning of October here in Edmonton – since just after we moved into the Mill Creek NetZero Home – and the fact that Edmonton has as many hours of sunshine as Miami has seemed hard to believe at times. Finally we have the return of sunny days, and the house is great to be in right now.

So what have we learned so far?

  • the transition to living on concrete floors has been painless for us. They are much warmer than I thought they would be, and since we were already in the habit of wearing Crocs around the house, I really haven’t noticed the different floor surface. We have been encouraging guests to put on a pair of Crocs from the box in the front entrance.
  • the house makes us much more in tune with the solar cycle. The above picture was taken at around 1 o’clock. I enjoyed sitting in the sun for a while before lunch, but now that I’m using the computer the sunny areas of the house aren’t appropriate anymore. Solar houses should have non-sunny areas, and the occupants must be willing to flex with what is going on outside.

Mill Creek NetZero Home - second floor library

the library area on the second floor is bathed in sunlight on a sunny day – luxurious at times, and to be avoided at others  read more... »

Passive Solar Design

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(MCNZH concrete floor being bathed by sun through a 9’x6’ window)

The most important design considerations for cold climate building are insulation, building envelope, and passive solar design. Given our lofty goals for the Mill Creek NetZero Home (MCNZH), we pushed hard to maximize our return on every one of these fronts.

The MCNZH collects 54% of its annual space heat through passive solar design – that’s 8747 kWh or 31.5 Gigajoules. It does so by:

  1. having huge south windows that are specially manufactured to maximize solar heat gain
  2. containing a large amount of thermal mass to absorb the solar heat when the sun shines
  3. having movable solar awnings that allow 100% of the sunlight to hit the windows during the heating season (the awnings are strictly speaking not a passive part of the solution).

I’ll discuss the first two bullets on this list, given that I’ve already described the movable awnings at length.  read more... »