54. The amazing earth tube

Tags: Energy Efficiency, Geothermal

Published November 8, 2013

Blog: Save money with a pipe in the ground - The story of the earth tube

Geothermal energy isn’t just about Iceland, volcanoes, lava and journeys to the centre of the earth. The vast majority of geothermal projects aren’t about tapping the fiery, red-hot core of the earth, but taking advantage of the relatively constant temperature of the ground below the frost line. The ground beneath our feet is as constant as death or taxes; it’s almost always between four to six degrees Celsius.

It isn’t sexy, but it’s effective. And while the majority of the geothermal projects today are geo-exchange ground source heat pumps, today we’re talking about the amazing earth tube.

What the heck is an earth tube?

Also called an earth to air heat exchanger it’s a set of plastic or concrete pipes that are buried underground and draw air into the building. The air flows through the earth tube and it is warmed or cooled by the ground’s constant temperature of about six degrees. The longer the earth tube the more energy transfer you get.

Six degrees doesn’t sound like a lot, but when you’re sweating through your shirt on a plus 30-degree day it makes a big difference.

According to Chorna when plus 30-degree air runs through the earth tube it is cooled by the earth to 23 or 24 degrees saving tons of energy on air conditioning. More…

Podcast: Earth Tubes: How a simple pipe in the ground could save you up half of your ventilation heating costs

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The earth tube is a humble, simple invention. It pre-heats or pre-cools the air coming into a building by running it through an underground pipe. If you go a meter or two underground the earth is a constant 4-6 degrees. By taking advantage of that free heat you can can save a ton of money. We explore a couple earth tube projects in this episode of Green Energy Futures. 



These resources relate to this episode. They may be helpful in many ways, but we list them only for your information. This is not an endorsement of any of these programs, services or organizations and we make no guarantees about the products or services these companies or organizations may offer.

Earth Tube Ventilation Systems — Applicability in the Canadian Climate

A literature review on earth tubes from the Canadian Mortage and Housing Corporation. GO >

Tags: Energy Efficiency

Energy Efficiency in a Cold Climate - The Epcor Tower

Epcor Tower is a 29-storey office tower located in Edmonton, Alberta, Canada. It is locatedat 53.3° latitude. The design temperature is -34°C in winter and 28°C DB/19°C WB insummer (annual 62°C delta). Various measures are applied to create an energy efficientbuilding in this climate. A high performance envelope is used to minimize the effects of largetemperature swings. Energy efficiency is also achieved by providing an outdoor air systemwith geothermal pre-heating and pre-cooling via earth tubes. Additional energy savingmeasures include exhaust air heat recovery, winter free cooling, and boiler stack condenserheat recovery. Using the energy saving measures presented, the building is expected toachieve a 41.4% energy use reduction. GO >

Tags: Energy Efficiency


Energy Efficiency in a Cold Climate, The Epcor Tower - White Paper

Earth tubes, rain water and the street: what do you think of the Epcor Tower? - Edmonton Journal 

Epcor Tower - Sustainable Measures

University of Alberta Eco-House - Details

Earth Tubes and Recycled Waste Heat - Tang and de Ridder