Earth wind & fire

Tag : Heat Exchange System

The system, which cost $3,300, consists of two two-metre byone-metre solar panels mounted on the southwest side of his home.When the sun strikes the panels, a solar-powered fan draws air frominside the house into the panels. As the air rises through a seriesof corrugated metal tunnels, its temperature rises by as much as 22degrees Celsius before re-
entering the house through a vent at the top of the panel. Athermostat controls the self-sufficient system.
"On a sunny winter day, it will hold the temperature in the wholehouse at 19 or 20 degrees Celsius. The only thing I would say isit's a little noisy, like a bathroom fan, when it's running,especially at the peak time in the afternoon," says McKenzie.
He says he'll be happy if the system pays for itself within 10years. After that, it will be money in the bank. Unfortunately,unlike solar hot water heaters and other systems, there are nogovernment rebates for solar hot air systems.
"It's one of my frustrations," he says. "There are so many barriersto doing this sort of thing."
The solar heat system is just one weapon in the war that McKenzie,his wife Keely Davison and their two young children are waging onthe evil empire of runaway energy consumption.
Isolara has just installed a solar hot water system that shouldmeet about 60 per cent of the family's annual hot water needs, asubstantial amount considering that a conventional hot water heateraccounts for 25 to 30 per cent of household energy consumption.Payback, according to the experts, is usually seven to eight years.
Solar hot water heating systems work by collecting the sun's energythrough solar panels or evacuated tubes, generally mounted on aroof.
A small pump circulates glycol, a liquid used to make antifreeze,in a closed loop to the roof, where it is heated by the panels ortubes and then returned to a heat exchanger in the basement. Thatexchanger heats household water, which is stored in a tank and thenfed to a hot water heater, reducing the amount of energy neededfrom the heater.
In the case of the McKenzie-Davison family, the system has beendeliberately oversized so that any energy not needed for hot watergoes to a radiant floor heating system in their basement and twobathrooms.
When the solar hot water system is not generating enough heat --say, during a run of cloudy days -- an on-demand tankless Polomahot water system kicks in for both household water needs and theradiant heat system. Because it heats water only when it's needed,the tankless system saves the energy that a conventional heateruses to keep water hot all the time.
With federal EcoENERGY and various provincial government rebates,the solar hot water and tankless setup cost the family about$12,000.
To further slash their energy use, the couple has unplugged thefreezer, limited their use of the clothes dryer, and switched fromincandescent to CFL and LED lightbulbs. They also put thetelevision and other appliances on power bars that they switch offto stop the small amount of "phantom" electricity that flows toelectronics when not in use.
"We kind of went on a kick," says McKenzie. "My wife even took thelightbulb out of the refrigerator."
The result? A staggering 45-per-cent reduction in their electricityconsumption over the past six months. The family also switched toBullfrog Power of Toronto which generates electricity usingnon-polluting sources, like wind and feeds it into the provincialgrid, reducing the province's reliance on "dirty" energy sources,like coal. It costs about $350 a year extra for Bullfrog power.
Talk to most wind and solar-generation advocates and they'll tellyou that it takes a big investment to live off the grid. In fact, afull-scale solar system for electricity would cost $50,000 or more.
As to the carrot of selling excess power to Ontario PowerGeneration, well, you have to produce a heck of a lot just to meetyour own needs.
The Minto EcoHome in Manotick, a demonstration house built inconjunction with Canada Mortgage and Housing Corp., useselectricity-generating photovoltaic panels along with a host ofother energy-saving technologies, including solar water heating.
The electricity-generating system alone is worth $85,000. The houseis designed to sell energy to the provincial grid, buying back onlywhat it needs, making it a net zero energy home.
Elsewhere in Ottawa, Nancy Ross and her family are enjoyingenvironmentally friendly air conditioning, thanks to their recentlyinstalled geothermal system, the same system that will keep themtoasty warm come winter.
The system cost $21,000 after government rebates, but it will payfor itself within 10 to 15 years and provide low-cost heat and airconditioning thereafter.
Also known as a ground source heat pump, the Ross system consistsof a closed loop sunk 85 metres into the bedrock. An electric pumpin the basement pushes a mixture of ethanol and water down the loopin the summer, drawing heat from the house and expelling it intothe earth.
In the winter, the system draws the ground's heat into a heatexchanger, which concentrates the energy and releases it into thehouse as cosy heat via a forced air system.
Geothermal can also be used for radiant floor heating. A couple ofheating elements in the furnace-sized pump unit kick in tosupplement the earth-based heat when the coldest winter days exceedthe geothermal system's warming capacity.
Nancy and Larry Ross opted for geothermal when they were faced withreplacing the old forced air furnace in the house they bought lastOctober.
"We asked ourselves, do we go with high-efficiency gas orgeothermal?, and this seemed the right thing to do," says Nancy."We built a new house five years ago and kicked ourselves for nothaving done this then. Now it doesn't matter what oil or gas pricesdo and we have the bonus of air conditioning without the noise orguilt."
The NextEnergy system, installed by RickMénard Heating and Cooling Ltd. of Ottawa, cost about $20,000after government rebates. Subtract the roughly $10,000 it wouldhave cost the Ross family for a new furnace and air conditioninganyway, and the extra cost for geothermal shrinks to $10,000.
Even with the roughly $750 a year it costs to run the pump, thefamily will come out ahead quickly. Payback on geothermal istypically 10 to 12 years.
Critics point out that some of the electricity used to power thesystem comes from Ontario's polluting coal plants, but if theprovince meets its commitment to closing those plants by 2014, theargument is moot. In any case, there are zero emissions from thehouse.
There are variations on geothermal, including a horizontal system-- depending on where you live. Prices vary accordingly, rangingfrom $20,000 to $40,000.
"Every case has to be assessed individually," says Derek Langdon,the technical sales consultant at Rick Ménard Heating and CoolingLtd.
He underscores the environmental benefits of the system. "Everysummer, 50 per cent of the sun's energy is absorbed by the earth. Ageothermal system draws on that mass all winter long, and then thenext summer, the whole thing happens all over again."
And while interest in geothermal energy is heating up rapidlythanks to soaring oil and natural gas prices, the hefty initialinvestment is still a deterrent.
"People don't tend to look at the big picture. If you look 15 to 20years out, these systems make a lot of sense."
For Nancy Ross, the choice is simple. "We don't think too muchabout spending $35,000 on a car, and that has no payback."