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Ductless Heat Pumps Determining Cost Savings Example

Ductless Heat Pumps Determining Cost Savings Example. Gary Nordeen Bill Kingrey, P.E. 11/5/08 AFE Webinar. Introduction. This presentation will help you to determine potential cost savings using ductless heat pumps. Step 1: Determine Fuel Costs. Real Fuel Costs Include: Taxes

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Ductless Heat Pumps Determining Cost Savings Example

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  1. Ductless Heat PumpsDetermining Cost SavingsExample Gary NordeenBill Kingrey, P.E.11/5/08 AFE Webinar

  2. Introduction This presentation will help you to determine potential cost savings using ductless heat pumps

  3. Step 1: Determine Fuel Costs Real Fuel Costs Include: • Taxes • Demand charges for electricity • Meter charge, minimum payments • Fuel consumption charges

  4. Calculate Fuel Costs • Divide total bill for each fuel type by # of units of fuel • Use a winter month bill for heating supplement and a summer month bill for cooling supplement Electricity = total bill / #kWh used Gas = total bill / # therms used Oil = total bill / # gallons used

  5. Step 2: Estimate Existing System Efficiency • Cooling Mode: divide seasonal energy efficiency ratio (SEER) of chosen heat pump by 3.413 SEER / 3.413 = Efficiency in cooling mode • Heating Mode: divide heating seasonal performance factor (HSPF) by 3.413 HSPF / 3.413 = Efficiency in heating mode

  6. Step 3: Calculate Cost of Energy Use the following table OR the Fuel Cost Calculators at www.nwBuildings.org/dhp.aspx

  7. Fuel Cost Table Cost Approx. FUEL Units Factor Efficiency #2 Fuel Oil $/gal .1396 .82 #6 Bunker $/gal .1524 .82 Coal $/ton 23 .77 Cord Wood $/Cord 18 .60 Electricity $/kWh .003417 1.00 Heat Pump $/kWh .003417 2.50 Natural Gas $/therm .1 .80 Propane $/gal .0915 .80 Wood Pellets $/ton 16 .77 Cost / mmBTU = Fuel cost / (Cost Factor x Efficiency) Alternative: Use handy spreadsheet at: www.nwbuildings.org/dhp.aspx

  8. Sample Calculations Follow The sample uses Fuel oil and Electricity prices to calculate the delivered cost of heating and cooling in a large building, then compares it with the cost of supplying heating and cooling with a ductless heat pump.

  9. Step 1: Calculating Fuel Costs Fuel Oil #2 Fuel oil @ $3.00/gal burned at 82% efficiency = $3.00 / (.1396 x .82) = $26.21 / mmBTU Electricity Electricity @ $.112 / kWh at 100% efficiency = .112 / (.003417 x 1.0)=$32.78 / mmBTU

  10. Step 2: Estimate Large Cooling System Efficiency • To calculate savings in a system to supplement cooling you need to know the efficiency of the existing system • Estimate the EER (8 to 18) of the chiller system – including cooling tower and pumps and divide by .03413 to obtain the efficiency • Or use efficiency of 250% for air–cooled units, 250 to 330% for water cooled units

  11. Gather the Information • Assume the building is newer and the water-cooled chiller runs at 300% efficiency • Assume the “real” cost of electricity is $ 0.12 / kWh • Cooling costs = $11.71 / mmBTU

  12. Determine Energy Costs for Ductless Heat Pump • SEER = 19 • COP = 19 / 3.413 = 5.57 = • 557% Efficiency • Fuel Cost is $ 6.30 / mmBTU • Fuel Cost Savings is $ 11.71 - $ 6.30 = 5.41 / mmBTU

  13. What Did We Learn? • The existing HVAC system is providing cooling at about twice the cost of the DHP • We can justify the DHP on cost savings for cooling-only • Can we justify the DHP on heating performance or improved comfort? • Repeat the analysis using the heat pump efficiency of HSPF/3.413 and the appropriate fuel cost and efficiency for the building heating system.

  14. More Information Northwest Building Efficiency Center www.nwBuildings.org/ Info@nwBuildings.org 866-929-6232

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