WHY EARTH TUBES?

Why Earth Tubes? When I first stumbled upon earth tubes, I was searching for a natural and passive means of air conditioning for homes. I remember seeing a photo of such a system in an arabic country in one of the many green architecture books I have read. I couldn't find that system, but was very pleased with what I had found. Earth tubes are a method to precondition the air for your home or building. The system is very simple, .tubes are buried under the ground where the temperature stays relativelly constant. There is an inlet for the ambient air to enter the system. As it travels through the tubes, it is conditioned by the temperature under ground. In the winter the air is warmed, in the summer it is cooled. The air then enters your building by an outlet using a small fan to keep the air flowing. Thus your air is pre conditioned.



Who am I? My name is Chris Carrier. I am a husband, a father, a student at Thompson Rivers University, an employee with the city of Kamloops, and have been a number of different things at different times and stages of my life. I am not a typical student, since I am in my early forties. I have been interested in green buildings and architecture since my days as a tree house dweller in Uclulet, BC. I am also a budding writer. My published works include "Dragon Problem's" by Hur publishing and an article entitled "Of Kids and Hobbits" published in Kamloops Momma, a local parenting magazine.



What is the goal of the research? The main goal of my research is to determine if earth tubes are a viable option for Kamloops, BC. In addition to this, I would like to find low impact technologies that could be used in the construction industry that could be used to lessen the environmental impacts of the way we do things in the construction industry. As the planet continues to warm, a leaner, meaner, way of constructing homes and buildings can be achieved, today. The technology exists to change course. I have taken my LEED Green Associate course and hope to incorporate some of the technologies into my research.



As part of my research, I have been building a small cabin on a relatives property. I have built an earth tube system and have been testing it throughout the summer. The cabin will become a sort of testing ground for different systems I am interested in. The cabin has been built old school, using a hand saw, a cordless drill, and a hammer and nails. I have been posting pictures on the blog to keep people updated with my project.

Monday, April 4, 2011

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
Givoni, B. (1994). Passive and low energy cooling of buildings . New York: Van Nostrand Reinhold.
Pita, E. G. (2002). Air conditioning principles and systems (4th ed.). Upper Saddle River, N.J.: Prentice Hall.
Galloway, T. (2004). Solar house a guide for the solar designer. Amsterdam: Architectural Press.
Vaitheeswaran, V. V. (2003). Power to the people: how the coming energy revolution will transform an industry, change our lives, and maybe even save the planet. New York: Farrar, Straus and
Giroux.Hastings, S. R., & Wall, M. (2009). Sustainable Solar Housing, 2: Exemplary Buildings and Technologies.. London: Earthscan.
Leyla Ozgener, Onder Ozgener ,An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling.   Renewable Energy, Volume 35, Issue 12, December 2010, Pages 2804-2811
Carmody, J., & Sterling, R. (1985). Earth sheltered housing design (2nd ed.). New York: Van Nostrand Reinhold.
Stein, B. (2006). Mechanical and electrical equipment for buildings (10th ed.). Hoboken, N.J.: Wiley.
John Hait, Umbrella homes, Popular Science, pg 64-66, Aug 1986
G. Mihalakakou, M. Santamouris and D. Asimakopoulos, Modelling the thermal performance of earth-to-air heat exchangers, Solar Energy, Issue 3, pages 301-305, September 1994
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.
Chiras, D. D. (2002). The solar house: passive heating and cooling. White River Junction, VT: Chelsea Green Pub.
Amjad Almusaed (2010).  Biophilic and Bioclimatic Architecture . London: Springer-Verlag.
Lechner, N. (2001). Heating, cooling, lighting design methods for architects (2nd ed.). New York: J. Wiley.
Dennis J. Hall, Nina M. Giglio,(2010) Architectural Graphic Standards for Residential Construction By American Institute of Architects. Hoboken, N.J.: Wiley.

1 comment:

  1. Would the earth tube be connected to the fresh air intake of the HVAC system? If so, this could be used any time of year to precondition the air, similar to the way an HRV works.
    In your test case will the air be drawn in by convection or by a fan? Will there be any mechanical HVAC in the cabin? Perhaps electric baseboards could be used to bump up the temperature in the winter.
    More citations could be added that support the research that you have completed this semester.
    How, specifically will you be measuring the temperatures? Will this be automated? If, so this could save a lot of time.

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