Mill Creek NetZero Home, December 15, 2009, 14:00.

As we approach the winter solstice and the three-month anniversary of our moving in, we continue to learn about our new house. These observations are mostly qualitative, because we don’t have the rest of our solar modules up, and we haven’t set up monitoring equipment yet. We are tentatively planning to remove the door of our wood stove on July 1st, 2010  and then monitor the house’s energy use for a year.  read more... »

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.

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)

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.

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

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.

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... »

Editor’s Note: I’ve written about Rob Dumont in the past. He is one of the fathers of the green building movement, and I’m very pleased to have permission to reprint one of his columns here.

By Rob Dumont

Have there been any recent advances in the area of passive solar heating for residences?

Passive solar heating has been known since the time of Socrates. However, it is only slowly catching on in Canada. Improved windows have made the recent advances possible.

In the 1970s there developed two schools of thought regarding how best to reduce space heating bills in residences using passive means. One school was called the “mass and glass” school. With this approach, large south facing windows would be used along with concrete slabs and heavy construction such as adobe. This school had a lot of proponents coming out of the south-western United States. New Mexico was a hotbed. New Mexico has an especially favourable solar energy climate and relatively mild outdoor temperatures compared with most of Canada. A photo of the David Wright Home in Santa Fe, New Mexico, is shown in Figure 1. In Figure 2 a cross section of the house is shown.

Figure 1. South exposure of the David Wright House in Santa Fe, New Mexico

(Photo Credit: Design for a Limited Planet, Skurka and Naar, 1976)

Figure 2. Cross Section of the David Wright Mass and Glass House

( Credit: Design for a Limited Planet, Skurka and Naar, 1976)  read more... »

(Pouring concrete, main floor, MCNZH)

A lot has been achieved in the three months since my last progress report.  read more... »

(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... »

MCZNH Solar Awnings (summer and winter positions)

The Mill Creek NetZero Home (MCNZH) will have a ground-breaking solar awning installed on its south face (introduced in Solar Awning Part 1). Essentially, it's a movable awning made out of photovoltaic (PV) modules. It will serve two functions: to shade the south windows in the summer and fall, and to tilt the modules so that they are always at an optimum angle to the sun. An analysis of the solar awning's net energy benefit follows.  read more... »

James Howard Kunstler says that we need to start building spaces that are worth caring about and living in. When we put up cheap, ugly buildings, as we so often do in Edmonton, we make our communities and homes less worth respecting and cherishing. Reinforcing this idea is Susan Susanka, author of the much acclaimed book The Not So Big House, who says that "a house that favors quality of design over quantity of space satisfies people far more than...those characteristics in  reverse."  read more... »

I've thought about the heating system for the Mill Creek NetZero Home (MCNZH) for months now. The home will need a very tiny amount of heat because it's so superinsulated, super sealed, and passize solarized. The computer model that simulates the energy performance of the house (using HOT2000) has the MCNZH using 2500 kWh. That's roughly 6% of the heat that my renovated (with new insulation and windows) 1950s bungalow uses.  read more... »

Constructing a net zero energy home in Edmonton, Alberta is extremely challenging because this is a cold place. Thankfully, it's also a sunny place. Still, in order to achieve the net zero standard, factors such as energy efficiency, insulating values and solar energy collection need to be maximized.

Peter the builder and I came up with the idea of an adjustable solar awning system that will increase by about 10% the amount of energy that the Mill Creek NetZero Home (MCNZH) produces annually.

I just wrote a proposal to help fund the prototype solar awning that we will put on the MCNZH. Here are some excerpts. Sorry for the formal tone, and warning: the following may be for eco-nerds only.

Passive Solar Energy

The MCNZH is designed to passively collect a large amount of solar heat through its south-facing windows. In fact, the 3642 kWh of solar heat that will be captured through the windows represent 46% of the annual space heating required by the MCNZH. With such a large area of south-facing windows, though, there is considerable risk of the home overheating.

In a home as well-insulated as the MCNZH will be, there are “…severe restrictions in the amount of south windows that can be used without excessive overheating” (CMHC, 2005, p.53). “Increasing the window overhang[, however,] allows for additional south glazing” (CMHC, 2005, p.54). In order to remain comfortable for its occupants, then, the south windows must be shaded by overhangs.

The installation of overhangs presents a compromise between maximum solar energy capture and occupant comfort. HOT2000 simulations show that the MCNZH will capture 314 kWh less annually if equipped with overhangs (HOT2000 is a residential building performance evaluation software distributed by Natural Resources Canada (Natural Resources Canada, n.d.)).  read more... »