By Patrick Langston, Ottawa Citizen
Goutam Shaw and Geeta Chowdhury really need to stop feeling guilty.
Despite having designed and built a remarkable eco-friendly home in Cumberland, Ont., the couple are still troubled by cutting down a corner of poplars and maples on their heavily treed property of four hectares.
"You can’t build a house without cutting some trees, right?" asks Shaw, sounding a tad defensive. "I’d like to plant some evergreens there," adds his wife, while pointing to their backyard that is also crowded with aspen and oak trees.
For a moment the pair seem to have forgotten about the recent story in SAB Homes, Sustainable Architecture & Building in Canada that details the eco features of their home, located just east of Ottawa. The magazine took pains to point out that the couple cut down trees that would have sucked 3,000 kilograms of carbon dioxide a year out of the atmosphere.
Yet their 4,000-square-foot home, which also includes a 3,200-square-foot basement, has zero emissions, meaning it is a good eco citizen. You only have to consider that heating a conventional house of the same size with natural gas would produce 13,000 kilograms of carbon dioxide a year.
It’s time to jettison the guilt. You can see the article, Build it Right, at sabmagazine.com. The detailed calculations scored their home a deep shade of green.
The couple’s design flair added a Mediterranean theme over the impressive technologies. It was Shaw, a technology entrepreneur who trained as an engineer, but knew nothing about homes besides paying the mortgage, who carefully mapped out the underpinnings of the house. From 2003 to 2007, he spent about three hours a night at the computer researching everything from construction methods to heating and cooling systems. "I investigated the life cycle of every material that’s in this house," he says. "I knew the house had to be eco-friendly and energy-efficient. That was the bottom line."
Together, the couple (Chowdhury is a patent examiner with the federal government) took architectural ideas from magazines, the Internet, wherever something caught their attention. Their design was so precise they didn’t have to make a single change during construction. Not that changes would have produced a designer-builder battle as sometimes happens: the couple acted as the general contractor.
The home’s airtight envelope employs ICF (insulated concrete form) technology with a twist. Because the production of regular concrete consumes large amounts of energy, Shaw used specialty concrete blocks from Durisol (www.durisolbuild.com) in Hamilton. The blocks are 80 per cent recycled wood chips and 20 per cent concrete with integrated rock wool insulation, and boasts an R-value of 21 below grade and 28 above.
Concrete has extraordinary thermal mass properties, meaning it holds heat for long periods in the winter. As a result, says Shaw, the blocks have an effective above-grade R-value of 36 when the thermal mass is added.
As well, unlike conventional stick frame construction where studs interrupt the insulation, there is no thermal bridging in concrete. That helps the material, when it is "charged" with heat, to hold the indoor temperature at about 20 C for extended periods. Heat is also distributed evenly through concrete’s thermal mass, virtually eliminating the islands of hot and cold that often plague conventionally constructed homes. As a bonus, in the summer the concrete will remain relatively cool, minimizing the need for air conditioning.
High-efficiency windows and doors round out the envelope. Even the fibreglass garage doors have an R-value of 16, more than the walls of many homes.
A geothermal system heats and cools the home, distributing warmed or cooled air through a radiant floor system. Fifteen temperature monitors throughout the home provide constant feedback to the system, keeping the indoor temperature remarkably constant.
Firing up his laptop, from which he can control the house’s heating and cooling system from anywhere in the world, Shaw projects his home’s energy performance on a big screen television. There, in a series of graphs and diagrams, is a real time and historical summary of temperature, energy use and more.
He frowns as he notices that the electrically powered auxiliary heater kicked in between 4 a.m. and 7 a.m. when the geothermal system alone wasn’t enough in the -25 C weather. That little problem should be resolved when he tacks on a supplementary solar heating system in the near future.
Shaw calculates that it will cost $1,900 a year in electricity to power his geothermal system. "We were spending $2,600 on natural gas for our (previous home). That house was only 15 years old and it was 2,800 square feet (with the basement)."
Seven hundred dollars less a year to heat and cool a place that’s almost three times larger — not a bad deal. He figures that even with the $60,000 cost of the geothermal system, including engineering and monitoring devices, he’ll recoup the cost in 10 years.
Shaw is no eco-saint.
He gets as big a bang out of engineering his energy-efficient home and helping to save the planet. He admits to driving an SUV, although his wife has a Prius. "Next time, I’ll look at something else, maybe an electric car."
Sinner or not, he’s built a slew of eco-friendly features into the cleanly designed, clutter-free family home.
The biofilter septic system produces 99 per cent pure residual wastewater. South-facing windows mean solar gain in the winter, heat which is soaked up by the concrete walls and handsome, tan-stained concrete floor. The generous kitchen (Chowdhury loves to entertain) features cabinetry custom made from reclaimed pine from an old barn and fast-growing bamboo.
Stairs to the second level are also bamboo, the absence of any dust on them evidence of the home’s high indoor air quality, rather than obsessive house-cleaning.
For the most part, materials in the home came from a 500-mile radius, reducing pollution associated with long-range transportation. As well, the vast majority of construction waste was recycled by the manufacturer or waste management company.
"We wanted something we were proud of," says Chowdhury of their home-building process. "It’s a good feeling that you’re doing something for the future."
All this cost the couple about $250 a square foot, including site preparation. That’s roughly 10 to 15 per cent more than conventional construction costs, Shaw says. He figures that, between energy savings and a growing environmental awareness, it’s a model that can be replicated in either single family homes or small apartment blocks, an opportunity he’s actively exploring.
If it all seems like a lot of work and effort for a place, albeit a handsome one, to hang your hat, maybe, like Shaw and Chowdhury, we need to start putting our decisions into a long-term context.
"I’ll be dead and buried by the time climate change gets bad," says Shaw. "I tell my daughter, ’It’s your generation and the one after that will be in trouble if we don’t change.’"
Ottawa Citizen
© Copyright (c)
http://www.daytondavis.com/
No comments:
Post a Comment