SENSATIONAL

INNOVATE2 solar thermalan average domestic solar thermal system provides about 15 per centof a home’s space heating and 70 per cent of its hot water.Who should consider solar thermal? Leigh Bond, president of ThresholdEnergies Corp., an alternative energy design/build contractor and anadviser to the NAIT program, suggests people who are building newhomes consider both solar thermal and geothermal, but acknowledgesthe decision comes down to what people can afford. Because ageothermal system relies on electricity to operate the heat pump,installing solar thermal can be a great way to offset electricity costs(which are greater with geothermal). For people retrofitting their homes,solar thermal (along with solar PV) is Bond’s recommended alternativeenergy technology.Pros• It can be easily installed when retrofitting a home.• It’s relatively inexpensive.• It contributes a significant amount of domestic water heating.Cons• Average systems provide only a small percentage of space heatingneeds.• Storage. “In one day, we get enough energy shining on the earthto last us the whole year,” Bond says. “The problem is, how do youstore that energy?”• A south-facing exposure is optimal.What people don’t understand about solar thermal: Albertans thinkthey can heat their homes with solar thermal, but that’s not the case.Cost: $9,800 for a family of four (Source: Bond)Return on investment: 15 years (Source: Bond)3 geothermal(also known as geoexchange, geothermalheat pump, a ground source heat pump orearth energy)electricity excluded, the average domestic geothermal system canmeet 82 per cent of your home’s energy needs, covering space heating,cooling and hot water (see chart below). This free low-grade energystored within the Earth’s crust is actually stored solar energy.Who should consider geothermal? “Every new home for sure and everynew commercial building,” Bond says. Geothermal is also being installedat the subdivision level in some new developments, which means thehomeowner doesn’t pay upfront for the piping in the ground (which isabout half the capital cost of geothermal), but is charged a monthly feeto access it. (And in this scenario, the capital cost is about $5,000 morefor geothermal compared to natural gas, Bond says). It’s also possibleto retrofit an existing home with geothermal, but even with the $4,375grant from the federal ecoENERGY Retrofit – Homes program, it’s acostly undertaking (remember, on a retrofit, you’ve got to dig up youryard and add the cost of re-landscaping to the job – and most peoplehave more than $4,500 in landscaping, Bond says).Pros• Energy stored in the earth is available at all times.• In Alberta, geothermal is 11 per cent more greenhouse gas friendlythan natural gas.• The pipes in the ground are a permanent asset expected to haveresale value, Bond says.Cons• It is expensive to install.• It increases the overall electricity consumption of your home.What people don’t understand about geothermal: People think thetemperature of the ground needs to be room temperature otherwiseit won’t work, Bond says. It doesn’t work like that. It works at coolerground temperatures.Cost: $50,000 (about half the cost is for the piping in the ground).Regarding the high upfront costs, Bond emphasizes that, apart fromelectricity, “Geothermal addresses 82 per cent of your annual energyneeds in one technology” – an amount he considers to be in line with theprice of installation.Return on investment: Eight to 11 years (Source: Bond)Residential energy useSpace heating 63 per centWater heating 17 per centAppliances 14 per centLighting 4 per centSpace cooling 2 per centTotal 100 per centSource: Natural Resources Canada’s Office of Energy Efficiency30 techlifemag.ca