BETTER BUILDINGS BY DESIGN Sheraton Conference Center Burlington, Vermont. February 8, 2012

Transcription

1 BETTER BUILDINGS BY DESIGN Sheraton Conference Center Burlington, Vermont February 8, 2012

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4 What is a geothermal System? Technically, it is a water source heat pump (WSHP) system that uses the renewable energy stored in the earth as a heat source, as well as a heat sink.

5 The British Thermal Unit (BTU) is the unit of energy used by the heating and cooling industry. 1 BTU = The amount of heat required to raise one (1) pound of water, one (1) degree Fahrenheit.

6 geothermal Systems EPA found that on a source fuel basis, geothermal systems are more efficient than competing fuel technologies. They are an average of 48% more efficient than the best gas furnaces, and over 75% more efficient than oil furnaces. In fact, today's best geothermal systems outperform the best gas technology, gas heat pumps, by an average of 36% in heating mode and 43% in cooling mode!

7 Residential applications usually consist of one or more WSHPs that all will typically be heating or cooling at the same time. Commercial applications are multiple WSHPs that when designed, will allow units to heat in parts of the building and cool in other parts of the building. This allows them to share their extracted or rejected energy.

8 Refrigeration Circuit Overview Air Coil Expansion Device Coax Reversing Valve Suction Compressor Discharge To Loop Source

9 Water has better heat transfer than air Improved low temp heating capacity Lower peak demand Outdoor ambient conditions, damage, and vandalism Noisy and unsightly outdoor unit Better dehumidification Higher efficiencies

10 COOLING 15.2 kbtu/hr water 12.0 kbtu/hr refrig work air 0.95 kw=3.2 kbtu/hr EER = 12.0/0.95 = 12.6

11 HEATING 11.6 kbtu/hr 15.3 kbtu/hr refrig water WORK air 1.08 kw=3.680 kbtu/hr COP = 15.3/3.68 = 4.15

12 38 F 44 F 50 F 50 F

13 Refrigeration Circuit Overview 53 F Cooling Mode (GS036) 80 F Air 60 F Coil Expansion Device Coax 60 F 76 psi Reversing Valve Suction Compressor Discharge 62 F 92 F 9gpm 90 F 100 F To Cooling Tower 155 F 218 psi a) Lvg air coil temp is lower than ent air coil temp is due to pressure drop through air coil. b) Suction temp at compressor is higher than lvg air coil temp because vapor

14 Refrigeration Circuit Overview 168 F Heating Mode (GS036) 70 F Air 107 F Coil 62 F 66 F 86 psi Reversing Valve Suction Compressor Expansion Device Coax Discharge 96 F 59 F 9gpm 168 F 248 psi 70 F To Boiler 62 F

15 Far exceeds ASHRAE 90.1 and qualifies for additional LEED points

16 Benefits Lower maintenance No water requirements Hurdles Requires land space First cost

17 3/4 pipe Six or Eight inch vertical bore. Systems based on Three (3) GPM flow per ton. Many areas require Bentonite (thermal conductive) grouting. Bore per ton Cold climates 150 ft per ton Warm climates 230 ft per ton

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19 Limited tonnage due to land area Backhoe or trench excavation. In areas with any rock typically backhoe only. Three 3 GPM flow per ton w/ 3/4 pipe Pipe per ton Cold Climates to 1000 ft Warm Climates to 1800 ft

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22 As the name implies, water is sourced from a well, river, or lake and after it goes through the geothermal equipment it is expelled back into the well, river, lake, or other drainage area.

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26 Geothermal System circa 1998 Complete exterior loop, mechanical room, interior PE piping, flushing and unit startup, heat pumps, duct work, exhausts, MUA system, timeclock-based controls $128,700 ($2,574 per ton) VAV System circa 1987 air-cooled condenser, VAV air handler, boiler, VAV boxes with reheat coils, economizer, electronic controls $100,000 ($2000 per ton) costs per building owner do not include structural or architectural

27 Garrett Office Buildings Edmond, Oklahoma

28 Geothermal Building Roof View

29 VAV Building Roof View

30 Geothermal Mechanical Room

31 Floor 1 Heat Pump Piping

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33 CWS Backflow Preventor Pressure Reducer/Relief Heat Pump Return Heat Pump Supply Expansion 3/4 Air Vent 2 PE typical Air Separator Bypass 3 Copper Pumps Primary/Standby Charging 2 PE typical Ground Loop Supply Ground Loop Return

34 Garrett Office Buildings 2000 Energy Consumption Profile

35 Garrett Office Buildings 2000 Energy Consumption VAV 15,000 ft^2 Geothermal 20,000 ft^2 Month Gas Mcf Elec kwh Gas Mcf Elec kwh Jan , ,920 Feb , ,880 Mar , ,960 Apr , ,120 May , ,600 Jun , ,400 Jul , ,120 Aug , ,480 Sep , ,120 Oct , ,840 Nov , ,360 Dec , ,600 Total , ,400 $ Cost $ 1,882 $ 17,899 $ $ 10,992 $/ft^

36 Comparative Analysis of Life- Cycle Costs of Heat Pumps Lincoln, NE school district compared leading systems for 3 new schools: System 150 Tons $/sq. ft. Geothermal WLHP $1,021,257 $14.66 Air Cooled Recip Chiller/VAV $1,129,286 $16.21 Water Cooled Cent Chiller/VAV $1,164,268 $16.71 Note: Air Cooled Chiller is 1kw/ton. Water Cooled Chiller is 0.6kw/ton. Vertical Bore Loop Field cost is $2.50 included in the Geo WLHP cost.

37 Antifreeze Piping Heat Pumps Bore Holes Installation Maintenance Financial Incentives

38 Methanol - least expensive and good heat transfer Ethanol - More expensive and best heat transfer Propylene glycol - non-toxic and expensive, but low heat transfer coefficient Blue Lightening #25 - Ethanol with inhibitors

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40 High Density polyethylene (HDPE )pipe developed for natural gas distribution industry Socket or Butt heat fusion joints are stronger than the pipe wall itself 3/4, 1, 1-1/4, 1-1/2, and 2 sizes common Coils and straight lengths Many fittings available in tee s, elbow s, and couplings

41 Polyethylene Pipe U-Bend

42 Goal: Design a product using EarthPure HFC-410A refrigerant and the most advanced components to create the highest efficiency WSHP on the market.

43 006, 009, 012, 015, 018, 024, 030, 036, 042, 048, 060, 070 Configurations Vertical Upflow Vertical Downflow Horizontal Extended Range 20 to 120 ºF EWT TXV metering device Geothermal (GLHP) or Boiler/Tower (WLHP) operation

44 Lower fan Watts during high speed operation Even lower fan Watts during part load compressor operation Extremely low Watts for fan only -- typically Watts Helps increase EER/COP, but also decreases annual operating costs due to significant runtime at part load and fan only

45 Very high efficiencies at full load Ultra high efficiencies on part load Unique unloading capability allows shift on the fly 67% capacity satisfies load 80-90% of the time, increasing annual efficiency

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47 Like any heating or cooling equipment the recommended maintenance should be followed. Specifically in a ground loop geothermal heat pump system, the quality and quantity of the water flowing through the WSHP is most important. Specified flow and cleanliness of the water is imperative.

48 The Federal Government as specific tax credits for commercial geothermal applications where the owner has a tax liability. Some may qualify for up to 48% of the total cost of the geothermal system. The IRS. on commercial geothermal as well as overall energy improvement in buildings has a tax deduction available. IRS Code 179D. Local State entities can provide incentives for geothermal and vary with the local.

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