This type of system is extremely useful when it is either really hot outside (like its been that last few summers) or really cold outside (like we have had in the past). What this system does is uses the consistent temp. of the ground to either cool down (summer) or heat up (winter) the air before it enters the building. This make the building heating/cooling systems use less energy trying to condition the air for the building thus making it run more sustainable. The system uses zero energy it is just a series of tubes in the ground. The same fans and pumps pull the air out of the tube just like it would from outside. A building has to have a percentage of fresh air replaced hourly so that the building does not build up carbon monoxide from people breathing in and out.
This system can also be used to help naturally ventilate your building as well. Creating a "stack ventilation" system will draw hot air out of the building thus pulling cooler air into the building thru the tubes all without the need for electrical devices. In our area this system will only work during certain times of the year. But the time it is working a building this size will be saving thousands of dollars in energy bills.
When it is cold outside the "stack ventilation" vents can be closed to help keep the warmer air within the building and Heating systems are only needed to heat small degree changes in outside air coming in from the tubes.
Here is a photo of a series of earth tubes being installed. The size of the tubes as well as the number depend on the size building you are trying to heat/cool. At the far end you can see a tube sticking straight up, that is where the air comes in. This can be positioned anywhere in the system, Ideally it is far from the building are vehicular traffic so it is pulling in clean air.
How do you calculate how far the 'run' of the ducts need to be to maximize the temperature change of the air in the ducts?
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My name is Andrew Stevens and I am a Graduate Student at the University of Oklahoma School of Architecture. This blog is for me to share with you my thought process and design images for a Net-Zero Velodrome in the Oklahoma City, OK area.