Published by City Farmer, Canada's Office of Urban Agriculture


Tiny bubbles to make your garden grow

As first appeared in the The Ottawa Citizen, June 22, 2002

by Erin Scullion

(Pictures of the solar greenhouse described below are found at: solar greenhouse)

How much fuel energy does it take to grow tomatoes in a Lanark County greenhouse in January when it's, like, -10 C outside? Well, if you're Kathryn and Ross Elliott of "Lively Up" Winter Harvest, less than $6 a month worth, or about $70 a year. That's instead of an estimated $3,000 a year to run a comparably sized greenhouse heated with propane or natural gas.

"Think of having a 100 watt light bulb on all the time," Mr. Elliott says. "That's about what it's going to cost us to heat and cool this greenhouse," he says, barely keeping his exuberance in check.

But how could you possibly do that for a 108 sq. meter (1,200 sq. feet) greenhouse built in McDonald's Corners, about an hour's drive west of Ottawa?

Well, first dig a one-meter by one-meter deep moat that can hold about 20,000 liters of water. Put up two layers of greenhouse plastic--one on either side of the moat--over a standard aluminum greenhouse frame.

Add five solar collectors, two foam generators (the kind the fire department uses), and an electric water pump. Then pour some plain old-fashioned dish detergent into the mix.

Flip a switch and the pump pushes the soap solution through the foam generator, spewing out millions of soap bubbles trapped between the two layers of plastic. This bubbling layer of insulation provides shading in the summer and heating in the winter.

Mr. Elliott is a certified energy advisor for EnerGuide for Houses, a federal government program overseen by Natural Resources Canada. He also operates Homestead Building Consultants, his own energy consulting business.

He estimates that the bubbles provide an insulation value equal to R-30.

"As far as we know, this is the first operational green house of its kind in the world," Mr. Elliott says, giving credit to Richard Nelson of Montreal, QC for developing the technology (visit for more information.)

The Elliotts are currently seeking additional funding from an outside source to help track, monitor and record the greenhouse operations. They're interested in launching a larger scale project in the future.

For Mrs. Elliott, the greenhouse is a dream come true.

"I just love to grow things. I've always loved to grow things," she says.

Besides earning a horticulture diploma from Algonquin College, Mrs. Elliott has worked in rural outreach programs in Japan, Jamaica and Papua, New Guinea.

It shows. The greenhouse is overflowing with carrots, parsnips, sweet peas, green peppers, lettuce, tomatoes, herbs, edible flowers and more. And she's one step away from being certified by the Organic Crop Producers and Processors.

Mrs. Elliott currently sells her organic produce to a bistro in the Byward Market and to friends and family. She'll soon be a regular at the Saturday organic farmers' market in Maberly and other local fairs. And she'd like to sell boxes of greens by special order throughout the winter.

But the couple's push for this greenhouse, innovative by any alternative energy standard, was to practice a sustain development system.

"The most important thing about this project in not the technology," says Mr. Elliott.

"Exactly" Mrs. Elliott interjects. "This is about being self-reliant and providing locally grown food for our community."

"Think of what it would be like if we converted half the greenhouses in the world to this system: climate change would slowed, fossil fuels would be reduced, and we'd have cheaper, better food, and healthier, more self-sufficient communities," Mr. Elliott adds.

You can contact the Elliotts at

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Revised Monday, September 16, 2002

Published by City Farmer
Canada's Office of Urban Agriculture