GeoExchange Systems Fact vs Myths David Petroy NTS Energy Consulting

GeoExchange Systems Fact vs Myths How it works Installation Benefits COP/Efficiency CO 2

What’s in a name? GeoExchange Ground Source Heat Pumps Geothermal Heating and Cooling GreenHeat Earth Energy Systems

If the earth is 50 degrees year around how can it heat my house to 72 degrees?

A series of pipes are buried in the ground either in trenches or sealed wells. Water is circulated in the pipes at a typical rate of 15 gallons per minute absorbing heat from the ground. The warm water comes up into a ground source heat pump unit that is similar in size to a furnace or a boiler. Heat Moving & Concentrating Machine

Heat Moving & Concentrating Machine We are not moving temperature we are moving heat Btu’s 15 gallons per minute of water lowering water temperature ~5 degrees btu/minute. Heat is “concentrated” into a refrigerant heating it up and then some additional heat energy is added in the compressor by compressing the refrigerant to make it hot enough (roughly 140) to heat you house. For cooling system just reverses.

How they work heating diagram

Will it work in the cold mountains of Colorado? Yes, it will work anywhere in Colorado. Ground temperature of 50 – water into geo unit at 50 out at 45 Ground temperature of 40 – water into geo unit at 40 out at 35 Same amount if heat energy heat pump just has to work harder lower COP.

I live in the mountains on rock can you drill there? Yes. It will be more expensive ( %) for the loop field However “hard” rocks have good conductivity so loop might be 10-20% smaller.

A bigger loop is always better because it is more efficient? Yes and No. Always more efficient yes. Better trade off between first cost and operating cost. There is a point of diminishing return. Over design can kill a good project. 40% more up front cost to increase efficiency 5%. There is an optimal design range which is a balanced trade-off between up front and on-going costs.

I have a small lot in the city how can you install geo there? Vertical loops Drill rigs with very small footprint.

It will contaminate the ground water No. Closed loop system with only one joint. Pressure tested twice. Grouted.

Horizontal loops are much cheaper than vertical loops Maybe so maybe no. “Much” cheaper, not in most cases in Colorado. Horizontal cost very dependent upon near surface geology and moisture content during dry times. If there is any doubt have provider quote both include landscaping costs.

I heard you can’t retrofit existing homes with geo Furnace and duct system - Yes. In-floor radiant heating – Yes (hybrid) Radiant baseboard – Yes with new distribution system Electric baseboard – Yes with new distribution system.

This is a new unproven technology Production systems since late 1970’s Thousands installed and working in Colorado Millions in the US. Ten’s of millions worldwide

Geothermal Heating and Cooling System Benefits Cuts energy use for heating by 60-85%, for cooling by 25-75% Very comfortable heating and cooling. Easy to implement the best IAQ systems. Low maintenance. Checks only every 2-3 years Can eliminate gas from your home if desired One unit for heating and cooling, no outdoor AC noise. Also can provide a good portion (25-50%) of your domestic hot water heating. 30% Federal Tax Credit Cuts annual heating and cooling bills by 65 – 80% vs propane or electric. Cuts annual bills by 25 – 65% vs natural gas. (insurance)

Energy Efficiency Terms COP – Coefficient of performance Furnace/Boiler -.8 to.96 Geo Air – 3 to 5 Geo Water – 2 to 4 EER + 3 ~= SEER GEO EER - 15 to 35

Facts and Myths Is it 2 or is it 5? Will the real COP please stand up! The unit. Incoming water temperature. Loop design, time of year.. Flow rate Output conditions (especially water to water units)

ARI (American Refrigeration Institute Ratings) Standard Conditions – Input loop water temperature 32 degrees full load Rating does include estimated loop pump energy For two stage geo systems ARI also has ratings for part load - Input loop water temperature 41 degrees Comparing units.

Actual Measured Vertical Loop Temperatures

Comparison Model COP over a year btu/hr design temp 0 degrees.

Total Electricity = kwh/year

Total Gas = 1525 therm/yr = 1525 * 29.3 = Fan electricity = 1211 kwh/yr Total electricity equivalent = kwh/yr

Geo = 10,735 kwh/yr Furnace = 45,803 kwh/yr COP - ~4.25 Geo/Furnace energy ratio =.24

Natural Gas vs Geo Annual COP Air Systems New Gas Furnace – best case COP =.95, worst case COP =.85 GEO – best case COP = 4.5, worst case COP = 3.0 Best COP ratio for gas = (3.0/.95) geo 3.2 times more efficient Best COP ratio for geo = (4.5/.85) geo 5.3 times more efficient.

COP for Geo Systems for Radiant Heating An efficiency distribution system that can work at low water temperatures is paramount for an efficient geo based radiant system. Output temperature 100 degrees – COP 2.8 – 3.5 Output temperature 120 degree – COP 2.3 – 2.8 (~25% less efficent)

COP in the field May studies in Europe, Canada, and U.S We have done field measurements in winter and loops typically run between 35 and 45 degrees Time of year affects measurement. Is system functioning well. It is impossible to design a loop that has a unrealistically low COP and still functions throughout the winter.

What about cooling Single stage geo vs 15 SEER AC uses about 25% less energy over summer Two stage geo vs 15 SEER AC uses about 50% less energy over summer.

Geo and CO2

Old Natural Gas Burning System – 75% to 85% energy efficiency –1.25 kwh energy input - 1 kwh heat output New Natural Gas Burning System – 85% to 95% energy efficiency –1.11 kwh energy input – 1 kwh heat output Old Propane Burning System – 75% to 85% energy efficiency –1.25 kwh energy input - 1 kwh heat output New Propane Burning System – 85% to 95% energy efficiency –1.11 kwh energy input – 1 kwh heat output All Electric Heating System – 100% energy efficiency –1 kwh energy input - 1 kwh heat output Ground Source Heat Pump Air System - 375% to 425% energy efficiency –0.25 kwh energy input – 1 kwh heat output Heating Systems Energy Efficiency At The Point of Use Note: 1 therm = 29.3 kwh, 1 gallon propane =.91 therms = 26.7 kwh

Heating Systems Carbon Footprint Propane – 12.7 lbs carbon/gallon,.476 lbs/kwh, EIA Natural Gas – lbs carbon/therm,.412 lbs/kwh EIA Electricity – 1.65 lbs per kwh, Xcel Colorado 2003 Old Natural Gas Burning System –1.25 kwh energy input (.52 lbs carbon) - 1 kwh heat output New Natural Gas Burning System –1.11 kwh energy input (.46 lbs carbon) – 1 kwh heat output Old Propane Burning System –1.25 kwh energy input (.60 lbs carbon) - 1 kwh heat output New Propane Burning System –1.11 kwh energy input (.53 lbs carbon) – 1 kwh heat output All Electric Heating System –1 kwh energy input (1.65 lbs carbon) - 1 kwh heat output Ground Source Heat Pump Air System –0.25 kwh energy input (.41 lbs carbon) – 1 kwh heat output

Heating Systems Carbon Footprint

Geo Economics Cost $20K - $35. Before Fed tax credit. Cost $14K - $25 After Fed tax credit Uses 60 to 80% less energy. 65 to 85% $ savings vs propane. 25 to 45% $ savings vs gas

Geo Economics Payback Three great assumptions: future price of natural gas/propane, future price of electricity, subsidies. Electricity: 2-5% annual increase Propane: 8-10% annual increase With current price of propane, 30% tax credit and inflation assumptions above years simple payback.

GeoExchange Systems Fact vs Myths David Petroy NTS Energy Consulting