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Investing in Efficiency:

Geothermal Heat Pumps in Indiana Schools

 

 

 

 

 

 

“There is an enormous opportunity for more money in education if we spend the dollar better.­­­­­­”

 

 

—Indiana Governor Mitch Daniels

Speech to the Indianapolis Rotary Club January 6, 2009

 

 

 

 

 

 

  

 

Michael Lutz and Taylor Cantril

DePauw University

March 16, 2009

 

I. Summary

 

A growing number of schools in Indiana and across the nation are turning to geothermal heat pumps (GHPs) to reduce their heating and cooling expenses. Although GHPs are initially more expensive to install, they offer immediate energy savings, cutting utility costs by 20% or more. After a payback period that is typically between 2 and 8 years, GHPs save money for the remainder of their 20+ year life. Furthermore, they reduce maintenance costs and provide superior classroom comfort. Unfortunately, their higher initial cost discourages some school districts from installing GHPs. The Indiana General Assembly has the power to solve this problem through a loan program. 

 

II. Introduction

 

Geothermal heat pumps (also known as ground source heat pumps or GeoExchange systems) have reliably heated and cooled large buildings since the 1940s, yielding consistent savings from the beginning (“Geothermal Heat Pumps”). A Washington State University researcher who surveyed some of the oldest systems in the U.S. concluded, “Based on over 50 years of operating experience, it is safe to say that earlier concerns over long-term reliability, operation, and maintenance costs were, to a large extent, unfounded” (Bloomquist 9).

 

This time-tested technology has a surprisingly simple basis. Below the frost line, the ground remains a constant 50-60° F year-round (“Schools”). Thus, it is a free heat source in the winter and heat sink in the summer. GHP systems tap this free heating and cooling potential by circulating fluid through underground pipes called “ground loops” (see the diagram below from EERE website; “Types”). Upon returning from the ground loop, the fluid enters the heat pump. This device further concentrates heat through the same process that air conditioning units and refrigerators employ. In the winter the heat pump draws warmth from the ground, heating the building. In the summer it runs in reverse, dissipating heat into the ground and cooling the building.

 

GHPs are highly efficient because they take advantage of the free heating and cooling potential of the earth. Instead of producing heat, they move it. Thus, they can “deliver between 2.5 and 4.5 units of heat for every unit of electricity consumed” (Oschner xiii). This reduces electricity usage “up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment” (“Benefits”). In recognition of this fact, the U.S. EPA has endorsed GHPs as “the most energy-efficient, environmentally clean and cost-effective systems for temperature control” (“Schools”).

 

 

III. Why the Indiana General Assembly Should Act

 

GHPs are especially suited for Indiana. While GHPs are not as flashy as wind turbines and solar panels, they have a far greater potential to cut energy use and utility costs (Jacobi). In lieu of other, less effective technologies, the Indiana General Assembly should consider focusing on one of the best energy efficiency technologies available: GHPs.

 

Furthermore, geothermal is one of the preeminent means of reducing spending on heating and cooling. The less money schools spend from their general and capital projects funds to cover ballooning utility costs, the more they can spend on teaching positions and classroom materials. Every new school built without a GHP system will be a burden to the school and to taxpayers for decades. Every school built with a GHP system is an investment in Indiana’s future.

 

IV. Benefits of Geothermal Systems

 

A. Energy Savings

 

The additional cost of a GHP is moderate, but the utility savings are significant. Mr. Mike Lindsey, Director of Maintenance for Southwest Allen County Schools, notes that “we expected the geo-thermal installations to cost 10-15% more than the traditional systems, but we also expected to save 20-30% on utilities (which we are seeing for the most part)” (“Additional Follow-Up”). Some schools can save even more. For example, Haverhill Elementary’s geothermal system is on track to reduce utility costs by 40% (Lindsey “Energy Conservation Report”).

 

After the energy savings have paid off the additional cost of the GHP, the system saves money for the rest of its life. Mr. John Gross, the maintenance official in charge of the Mount Vernon Community School Corporation’s three geothermal systems notes that the ground loops typically have a 30-50 year warranty, while the heat pumps last from 15-20 years.

 

B. Maintenance Savings

 

GHPs substantially reduce maintenance expenses. The ground loops are protected from the elements, and therefore are not subject to the damage and corrosion that plague conventional systems. Tom Perry, an engineer with 27 years of experience notes: “Because you don’t have a boiler or a chiller involved [in a GHP system], there is less equipment. It’s proven that the maintenance costs for ground source heat pumps are less than conventional systems, which improves savings and the bottom line for schools” (qtd. in Perry).

 

Furthermore, GHPS eliminate the need to replace chiller towers and other outdoor equipment used in conventional systems.  Jay Wise, the Facilities and Project Manager for Clark-Pleasant CSC, estimates that these avoided replacement costs can be as high as $400,000 over the 50-year life of the geothermal ground loops (“Testimony to House Committee”).

 

Mr. Gross explains another benefit of geothermal systems: when traditional HVAC systems fail, a whole wing of the school is left without heating or cooling. In contrast, with a geothermal system each classroom has its own GHP. This not only minimizes the disruption for students and teachers when the HVAC system fails, it also reduces the cost of maintenance in any given year. It is better to have a series of small repair jobs than one catastrophic blow to the maintenance budget.

 

C. Improved Heating and Cooling

 

GHPs offer benefits that cannot be measured in monetary terms. For example, they give teachers more power to keep their classrooms comfortable. Mr. Gross explains that with GHPs, each room can be heated or cooled individually. Other systems affect an entire wing of the school, making it harder for teachers to maintain optimal conditions. According to Mr. Lindsey: “We have also experienced an improved learning environment through better control of temperature and humidity [with GHPs]” (“Additional Follow-Up”).

 

V. Case Studies

 

A. Geothermal "Twin" Saves Energy and Money

 

It is very difficult to establish a baseline HVAC system price and energy use rate to determine exactly how much money GHPs save. Luckily, a remarkable pair of schools in Murfreesboro, Tennessee helps solve this problem. According to Gary Anderson, the Finance and Administrative Services Director of Murfreesboro City Schools, “The two schools compared in this study are the same square footage, about the same number of students, designed by the same architect, built by the same construction company located in the same city and built just two years apart from each other” (“Geothermal Research”). The only notable difference is that one school uses a GHP system, while the other uses a conventional system. 

 

Because the schools are so evenly matched in all other variables, it is reasonable to attribute the reduced energy costs of the geothermal school to its GHP system. The GHP resulted in marginally increased construction cost, but also remarkable energy savings. Mr. Anderson explains: “It cost us right at $400,000 more to build the geothermal system than the traditional 4-pipe system. We anticipated a pay back to be about 6-7 years. As you can see from our actual usage, we will pay it back in less than two years and then every year after that save a tremendous amount of money for the district” (“Geothermal Research”). The table below is a simplified summary of the information in “Murfreesboro City Schools Utility Usage Comparison.” Except for Average Cost / Ft ² / Month, figures are rounded to the nearest dollar.

 

 

Electricity, Water, and Natural Gas Expenses August 2007-July 2008	Scales Elementary: Four Pipe HVAC Plan	John Pittard Elementary: Geothermal Plan	Savings
Total Utility Costs	$423,845	$183,426	$240,419
Average Cost / Month	$35,320	$15,286	$20,035
Average Cost / Ft 2 / Month	$0.267	$0.116	$0.151

 

Since July 2008, the geothermal system at John Pittard Elementary has continued to save money. According to Gary Anderson, Pittard spent $78,500 on total utilities for the five-month period between August 1 and December 31, 2008. Scales spent $199,150 for the same period (“Geothermal Update”). The geothermal system uses only 39% as much energy as the conventional system.

 

B. Savings in Two Pendleton Schools after Geothermal Retrofits

 

Two schools in Pendleton, Indiana offer another example of geothermal’s money-saving potential. While the Murfreesboro schools show savings between two otherwise identical schools over the same period of time, the Pendleton schools show how a GHP retrofit reduces utility costs in comparison to an old system. By installing GHPs, the schools saved $58,622 and $43,853 per year (“Energy Cost Comparisons”).

 

Other factors may hide the full extent of the savings. In addition to installing GHPs, the renovations increased ventilation rates (which raise heating and cooling costs) and increased electricity use from lighting and computers (“Energy Cost Comparisons”). Additionally, the figures listed below do not account for decreased maintenance costs: “By eliminating boilers, chillers, cooling towers, open system water treatment, and support equipment, we eliminate the maintenance service contracts and replacement costs of these items” (“Energy Cost Comparisons”). Thus, the savings are likely to be far higher than approximately $40,000 to $60,000 per year. 

 

Pendleton Elementary Utility Costs	2004	2007
Gas	$79,636	$4,424
Electricity	$84,060	$100,650
Total Costs	$163,696	$105,074
Savings		$58,622

 

 

East Elementary Utility Costs	2004	2007
Gas[*]	NA	NA
Electricity	$159,934	$116,081
Savings		$43,853

   

Works Cited

 

Anderson, Gary. “Geothermal Research.” Email to Michael Lutz. 12 Dec. 2008.

Anderson, Gary. “Geothermal Research Follow-Up.” Email to Michael Lutz. 12 Dec. 2008.

Anderson, Gary. “Geothermal Update.” Email to Michael Lutz. 16 Jan. 2009.

Anderson, Gary. “Murfreesboro City Schools Utility Usage Comparison: Twelve Month Study Results from August 2007-July 2008.” Murfreesboro City Schools. Microsoft Excel spreadsheet sent by Gary Anderson to Michael Lutz via email. 12 Dec. 2008.

“Benefits of Geothermal Heat Pump Systems.” U.S. Department of Energy: Energy Efficiency and Renewable Energy (EERE). 12 Sept. 2005. U.S. Department of Energy. 26 Dec. 2008. <http://apps1.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12660>.

Bloomquist, Gordon. “Commercial Geothermal Heat Pumps.” Washington Sate University Energy Program. 1999. Washington State University. <http://www.enerssgy.wsu.edu/documents/renewables/geo_heat_pumps.pdf>. 15 Dec. 2008.

Campbell, Lonnie. Phone interview with Michael Lutz. 19 Nov. 2008.

Daniels, Mitch. “Budget Address.” Indianapolis Rotary Club. 6 Jan. 2009. <http://www.indystar.com/article/20090106/NEWS05/90106049>.

“Energy Cost Comparisons at Pendleton and East Elementary.” South Madison Community School Corporation. Microsoft Word document sent by Randy Stair to Michael Lutz via email. 16 Sept. 2008.

 “Geothermal Heat Pumps.” U.S. Department of Energy: Energy Efficiency and Renewable Energy (EERE). 1 May 2008. U.S. Department of Energy. 15 Dec. 2008. <http://apps1.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12640>.

Glentzer, William. Phone interview with Michael Lutz. 20 Nov. 2008.

Gross, John. Phone interview with Michael Lutz. 12 Dec. 2008.

Jacobi, Sara E. “For Energy, Noble and Greenough Goes Geothermal.” The Boston Globe 2 Sept. 2007. 15 Dec. 2008. <http://www.boston.com/news/local/articles/2007/09/02/for_energy_noble_and_greenough_goes_geothermal/>.

Lindsey, Mike. “Geothermal Information.” Email to Taylor Cantril. 9 Dec. 2008.

Lindsey, Mike. “Geothermal Information Follow-Up.” Email to Taylor Cantril 11 Dec. 2008.

Lindsey, Mike. “Geothermal Information Additional Follow-Up.” Email to Taylor Cantril. 11 Dec. 2008.

Lindsey, Mike. “Energy Conservation Report for June 2007-May 2008.” Southwest Allen County Schools Maintenance Service. Microsoft Word document sent by Mike Lindsey to Taylor Cantril via email. 9 Dec. 2008.

Ochsner, Karl. Geothermal Heat Pumps: A Guide for Planning and Installing. London: Earthscan, 2008.”Test

Perry, Amy. “Geothermal: Engineer Says Systems can Lower Costs.” School Construction News. 11 Nov. 2007. 15 Dec. 2008. <http://www.schoolconstructionnews.com/ME2/Audiences/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=3B6A2F3DB63E4DC292A7F04FBC171746>.

“Schools Look to Reduce Carbon Footprint by Using Natural Energy Resources.” Indiana Department of Education Spotlight on Renewable Resources. April 2008. Indiana Department of Education. 15 Dec. 2008. <http://www.doe.in.gov/edmatters/ed_matters_apr08/pdf/Success%20Story%20apr08.pdf>.

Stair, Randy. “South Madison Data.” Email to Michael Lutz. 15 Dec. 2008.

“Types of Geothermal Heat Pump Systems.” U.S. Department of Energy: Energy Efficiency and Renewable Energy (EERE). 12 Sept. 2005. U.S. Department of Energy. 15 Dec. 2008. <http://apps1.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12650>.

Wise, Jay. “Testimony to House Commerce, Energy, Technology, and Utilities Committee.” Indiana State Capitol Building. 22 Jan. 2009.