green building

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:  read more... »

Scrap Metal (Part 1)

Metals are easier to recycle than many other substances. They can usually be melted down, and the quality of the end product is very high. This contrasts sharply with plastics, which always degrade to a substantailly lower-valued product when recycled.

Recycling metal is much more energy-efficient than mining it from scratch, so "mining" it from a house that's going to landfill is the right thing to do.

I've spent the past two workdays ripping metallic things out of the house that the Mill Creek NetZero Home will replace.  It's dirty work that pays very little.  read more... »

Geothermal Heating

The proper term is "ground source heat pump" (GSHP). I often get questions about this technology, and I think that there are some misconceptions out there, so here goes.

How It Works

The way I think of it, there is a magical black box that can take heat at low temperatures and "pump" it up to higher ones. In Edmonton, the ground a few feet below the surface remains at about six degrees Celsius all year round. This is seasonally-stored solar energy - it accumulates in summer and doesn't cool very much during the winter because there's just so much dirt.

So, a contractor comes and drills long holes (150 - 200 feet, I think) in the back of your yard, and runs tubing down the holes. Then, when heat is needed, the heat pump runs a fluid through the tubes in the earth, and pulls solar heat from it. The exact same effect happens in reverse.

With a GSHP, you can pull 3 - 3.5 units of heat from the earth for every unit of electricity that the heat pump uses.

The Hype - Imported From Elsewhere

Using a GSHP is a brilliant idea in Manitoba or Quebec or Vancouver Island - somewhere where no natural gas is available. The thing is, if your only choice is heating with electricity, a GSHP is in effect 350% more efficient than regular electric heating. That is, with regular electric heating (like from a resistance heating baseboard heater), you get one unit of heat for every one unit of electricity invested. As stated above, the GSHP will give you up to 3.5 units of heat for every one. That's pretty good.

The brilliance of the GSHP in other locations, though, doesn't necessarily translate to Alberta. Here, natural gas is available ubiquitously. AND our electricity is mostly derived from burning coal - the enemy of the human race.

So in Alberta, the only fair comparison for a GSHP is a super-efficient natural gas furnace.

Electricity vs. Natural Gas

Most of Edmonton's electricity is generated by burning coal near Wabamun lake. The generators burn the coal, and convert about 30% of the energy in the coal into electricity. Then, it gets sent down the power line to our great city (some of it gets lost along the way, but we'll ignore that for now). If we use the electricity in a GSHP that is 350% efficient, we get 3.5 units of heat back for every 1 put in. The thing is, we're using electricity that contains only 30% of the coal's original energy value. 30% * 3.5 = 105%. A coal-fired GSHP is 105% efficient, then, when considering the energy that was initially in the fossil fuel.  read more... »

Give It Away

The Edmonton Earthcycle network is an unheralded success story. It's been around for years now, as a way to give and get free, unwanted things. With over 12,000 members and 200-250 messages (either offerings or request), it diverts an amazing amount of stuff from the landfill. And just imagine all of the great karma that it helps create!  read more... »