ABSTRACT OUTLINE: VERSION 1.0

Abstract Outline:

As the planet warms, solutions to the growing crisis of climate change are evolving at a dizzying pace. Many of the solutions being proposed are mechanical in nature and may end up being part of the problems of the future. As is often the case with new and untested technologies, these new systems have been found to be just as harmful if not more harmful than their predecessors. Such is the case with regards to HFC’s (hydro fluorocarbons) when they replaced CFC’s in air conditioning units.  The United Nations Environment Program (UNEP) later found that HFC’s were up to ten thousand times more harmful.  In order to avoid these future problems, it has become important to research systems that are passive in nature, meaning they have few if any moving parts, and require no chemicals. An example of a passive building, The Eastgate Building in Harare, South Africa, uses biomimicry for its cooling system. The cooling system is modelled from a termite mound. The results of this passive system are astounding. The building uses only 10% of the energy that a conventional building of similar size would use, lessening the costs of construction, and contributing to a reduction in operating costs and even the costs of rent. This shows that often the simplest solution to a problem is the best solution.

How does an earth tube system perform with respect to the passive cooling of residential buildings in Kamloops, BC?

The Air Tube Concept:

Earth air tube systems were developed during the 1970’s and 1980’s as a method of providing natural cooling and air circulation to a home. The system is passive in nature and uses air circulation or more specifically air convection to power the air flow. In other words, there are no moving parts. The system is described as follows; One end of the pipe acts as an inlet for the ambient outdoor air. The other end of the pipe brings the air to the interior of the building. As the ambient air travels through the pipe it absorbs the cooler temperature through conduction and the cooled air enters the building. The system can be completely passive; however, a small fan can be used to augment the airflow. The warm air is then forced out of the building via a small air vent. The system remains working due to the convection of the warm air and cold air thus ensuring a steady supply of cooled air being brought into the house.

According to F. Al-Ajmi, in his research paper titled “The cooling potential of earth-air heat exchangers for domestic buildings in a desert climate”, earth tube systems can reduce cooling demands by up to 30% or by as much as 1693 kWh for the duration of the summer months.

Building simulation:

Research will be performed on a system of earth tube in Barnhartvale, where a small cabin will be constructed, and several earth tube runs shall be constructed. There will be two primary types of earth tube systems; the first two sets shall be buried under the ground at 8’-0” and 6’-0” in depth. The air intake for the 6’-0” depth system shall be placed in the shade where the air is always cooler, while the other intake shall be placed in full sun. A third run shall be placed under water. Several measurements shall be taken. The ambient outdoor air temperature shall be measured at the inlet of each tube, and the temperature of the air coming into the building from the individual tubes shall be measured. The difference of temperatures shall be plotted on a graph to determine the efficiency of the system.

Conclusion:

Air tubes alone cannot replace a mechanical air conditioner; however, in conjunction with smart passive designs, a well designed building envelope with good insulation, modern windows, and night-time venting, a passive system may be able to maintain indoor thermal comfort during the warm summer months. Thus a passive system is attainable.

References Cited:

F. Al-Ajmi, D.L. Loveday, V.I. Hanby (2006) The cooling potential of earth-air heat exchangers for domestic buildings in a desert climate. Building and Environment, volume 41 pages 235-244

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F. Al-Ajmi, D.L. Loveday and V.I. Hanby. The cooling potential of earth–air heat exchangers for domestic buildings in a desert climate. Building and Environment, Volume 41. Issue 3 March 2006, pages 235-244.

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