Kermit the Frog always said it was so hard to be green...he was wrong! Ground source heat pumps can make your home NetZero without doing much to the home. When combined with other renewable technologies such as wind, solar, building a more energy efficient building and selecting efficient appliances, it's not even that hard to get off the grid completely...
Our home was built in 1966 and it was built to the standards of the day. It’s not super-insulated and there are no solar panels generating electricity on the roof. We did install triple pane windows about 20 years ago, so it’s a pretty normal home. We live in the cold Canadian prairies where it drops to -20°C every winter, -30°C most winters and -40°C occasionally.
My home is also Net Zero. The ground under my home produces about 21,400 kWh of thermal energy that heats and cools my home and heats about 50% of my hot water. It actually produces more energy than I purchase from my electric utility…so actually, my home is NetZero Plus.
I purchase about 18,500 kWh of electrical energy from my electric utility…about 13,100 kWh to run our appliances, TV, hot tub and lights, and another 5,400 kWh to power our ground source heat pump and circulation pumps. The ground produces about 2,900 more kWh of energy than I need! Not bad for a 50 year old home.
The worst part about it is that there’s really not much to see. The odd person might notice there’s no chimney or gas furnace vent…but it looks like a pretty normal home. If you had X-ray vision you might notice about a dozen pairs of plastic pipe stuck into the ground to about 60’ deep. Nothing to advertise that it’s really pretty energy efficient and doesn’t produce any greenhouse gases. A few might notice there’s no noisy air conditioning compressor making noise in the side yard, but in our long, cold winters it’s not something most would notice.
The ground source heat pump was installed in 1993. For 23 years now we haven’t burned fossil fuels. The gas meter’s gone. I upgraded the heat pump about a year ago. Removed the old heat pump and connected the new, more efficient model to the same pipes in the front yard.
I’m not the only one in Canada with a NetZero home. There’s about 120-130,000 homes with similar systems…and most of them are also NetZero. In fact the ground under a typical home produces about twice as much energy as the home owner purchases. A typical Canadian home, according to the Office of Energy Efficiency, consumes 30,500 kWh of energy for heating, cooling, heating water and running appliances and lights. That energy use is broken down in the following drawings. The image on the left illustrates total energy consumption in a typical home. About 4,900 kWh are used by appliances and lights, an additional 25,600 kWh of energy are used to heat and cool the home and produce hot water. In a typical home that energy is purchased from electric and gas utilities.
In a home with a ground source heat pump, 4,900 kWh are purchased to run appliances and lights. About 7,800 kWh are purchased to run the ground source heat pump…for a total of 12,700 kWh of purchased energy. The rest of the energy used to heat and cool the home and produce hot water is delivered to the home directly from the ground around the home. The ground produces more than double the energy than needs to be purchased.
That has some pretty interesting implications. The home is already NetZero…more than twice as much energy is produced from the ground than needs to be purchased…and that energy is renewable! If the homeowner wanted to completely disconnect from the utility, it’s suddenly become much easier. Solar cells that produce 12,700 kWh provide all the energy needed to run the appliances and lights as well as completely heat and cool the home and produce all the hot water.
CO2 emissions in the home with the ground source heat pump are reduced by about 5 tonnes compared to a home with a gas furnace, depending on how your electricity is generated. If it’s hydro-electric, it’s reduced to virtually no emissions.
There are even bigger implications for electric utilities. Electric utilities have to generate enough electricity to meet the requirements on the hottest or coldest day…the peak loads. If they are building a new dam, every kW of energy requires a capital investment of about $8,000 or $9,000. That’s about enough to run a toaster! Even the cheapest generating station…a natural gas turbine…costs about $1,800 capital investment to produce 1 kW.
There are a lot of Canadians that use electricity to heat their homes…electric baseboards or electric furnaces. The typical home needs about 9 or 10 kW on the coldest day. The same home with a ground source heat pump only needs less than 3 kW...about 7 kW less. That’s power the utility doesn’t have to supply to that home…and eliminates the need to spend at least $12,600 to build a new gas generator…or about $60,000 to build a new hydro-electric dam, and who knows how much for a nuclear plant.
The cost to install a ground source heat pump in a typical home is about $20,000. That’s a lot less than spending $60,000 for a new dam to produce the same amount of power. The energy freed up by the homes also addresses the greater electrical demands electric vehicles will put on generating stations and distribution power lines in the coming years.
Taking the next step
That’s for a typical home. Let’s go a step farther. Say the homeowner built a home with better insulation and windows and selected more efficient appliances and lights. Now, instead of 4,900 kWh to run the lights and appliances, they might only need 3,000 kWh. And because the home is better insulated, a smaller heat pump could be used…say it only needed 12,000 kWh to heat and cool it. If a more efficient heat pump was selected, it might only need 3,000 kWh per year to power it. Solar panels that generate 6,000 kWh could take that home completely off the grid when combined with the renewable energy the ground produces.
That makes the home completely carbon free! The combination of a ground source heat pump, solar panels, a more efficient building and appliances eliminates the homeowner’s energy cost.
So you can see, it’s not that tough being green! Even if you own a typical home. If you’re building a new home, combining energy efficient construction and selecting efficient appliances, and combining that with a ground source heat pump and solar panels can take you completely off the grid!
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.