Save Precious Water With Geothermal Heating and Cooling

Geothermal-Sourced Chillers Save
Billions of Gallons of Fresh Water

Think about the types of building materials that have endured. For example, cement, concrete block, gypsum, and good old fashioned wood/lumber. These have all endured as building materials favored by many. Water has certainly endured as a medium for heating and cooling. Commercial buildings pump the lifeblood of cooling and heating systems through a building in the form of chilled or heated water, depending on the needs of the building. 

Geothermal heating and cooling (HVAC) completes this wonderful cycle by coupling buildings with the shallow Earth, just like a tree’s root system. Closed loop piping filled with life-giving water circulates, transferring the heat to and from the Earth, similar to the way tree roots transfer the essentials of life from the Earth through their branches and leaves. This is perfect symbiotic sharing of energy with the Earth, and is as close to nature as one can get in the process of heating and cooling of building.

Like a Tree's Root System, Geothermal Couples a
Building with the Shallow Earth to Transfer Energy

With respect to refrigerants, water is called "R–718". It has impressive thermal properties, and can be engineered through the established fluid flow practices to efficiently transfer heat to and from a building, using far less energy than forced air systems, and significantly less energy than is needed for refrigerant flow based systems. I mentioned refrigerant flow, because there seems to be a fad of sorts involving equipment with multiple evaporators in homes and commercial buildings. Whether these variable refrigerant systems with multiple evaporators are geothermal sourced or not, the fact remains that pumping refrigerant through building uses more energy, is not natural, and you might wonder what the long-term effects are, as well as the energy efficiency aspects.

Fact is that recent studies prove unequivocally that refrigerant flow takes more energy per BTU than just pumping water. Commonly use refrigerants (other than R-718, water) must be pumped at high velocity to keep the compressor oil en-trained within the stream running through the refrigerant piping. This high velocity pumping wastes significant power when compared with hydronic (water based) heating and cooling systems.

Greg Cunniff, co writer of the book, "Modern Geothermal HVAC Engineering and Control Applications McGraw-Hill 2013”, has done significant research on the subject, some of which can be seen in results from comparisons at the headquarters of ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) in Atlanta.

Water seems limitless, especially when looking at the oceans, which cover about 2/3 of the planet.  Fresh water is not as abundant.  Most of it is in our aquifers, and it’s important that we conserve this resource. Used for drinking water is OK, but using water for things like cooling a building might be a little reckless. 

Commercial buildings, hotels, airports, factories, schools, shopping centers, high rises and power plants use cooling towers to cool down their air-conditioning, refrigeration, and process loads in their facilities. Cooling towers use evaporative cooling principles to decrease equipment size and increase energy efficiency.

Cooling Tower Consumption of Fresh Water is
Eliminated By Geothermal-Exchange

These commercial facilities have a many needs for fresh water that include sanitary, irrigation, and cooling tower.  According to the EPA, about 25% of the water used in office buildings is for the cooling load.  In process cooling applications like laboratories and manufacturing, the consumption for cooling towers is more than 50% of the total consumption of fresh water.

To put this into terms of gallons of water, a typical 50,000 square foot high school will use about 30,000 gallons of water per day; enough to fill two basic swimming pools.   Indianapolis International Airport can use a million gallons of fresh water just for cooling on a summer day.

Geo Saves Fresh Water and Increase Longevity and Resiliency

The US had between 71 and 81 Billion square feet of commercial space in 2010, served by 2 to 3 billion tons of cooling capacity.   [based on floor space estimates from DOE report] This represents between 1 Billion and 3 Billion gallons of fresh water consumption each day.

In our efforts to conserve Earth’s water resources, geothermal sourced heating and cooling will save billions of gallons of fresh water. Some locations can use surface water, others will use ground coupled exchangers, and many will use aquifer thermal exchange

Summary:

Hydronic (water-based) geothermal heating and cooling systems are the most energy efficient HVAC systems in the world today. Less is more; simple is better.

More information on Geo? Just use #GeoDay2015 for social media, and checkout the Geothermal Day Website , IGSHPA and the Geothermal Exchange Organization. 

Jay Egg is a geothermal consultant, writer, and the owner of EggGeothermal. He has co-authored two textbooks on geothermal HVAC systems published by McGraw-Hill Professional. He can be reached at jayegg.geo@gmail.com .