Economic Evaluation of Residential Air Conditioner Designs for Hot and Dry Climates

Economic Evaluation of Residential Air Conditioner Designs for Hot and Dry Climates Arthur Rosenfeld, California Energy Commission Gregory Rosenquist, Lawrence Berkeley National Laboratory C. Keith Rice, Oak Ridge National Laboratory ARI Spring Product Section Meeting Reston, VA. April 18, 2005, modified on 4-20 ARosenfe@Energy.State.CA.US

California has lower per capita electricity use than the rest of the country Total Electricity Use, per capita, 1960-2001 14,000 kwh 12,000 U.S. 12,000 10,000 8,000 8,000 6,000 4,000 2,000 0 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 KWh 1994 1996 1998 2000 7,000 California Californians have avoided annually $1500/family 2

Daily peak loads in California are highest during the summer 50 45 40 Cal ISO Daily Peak Loads January 1, 2000 - December 31, 2000 Peak Day August 16-43.5 GW Commercial AC GW 35 30 25 Residential AC 20 Jan-00 Feb-00 Mar-00 Apr-00 May-00 Jun-00 Jul-00 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 3

DOE has funded research at ORNL to develop A/C designs for hot/dry climates Several Hot/Dry designs were developed by ORNL relative to a conventional baseline design Three Hot/Dry designs were adapted for economic evaluation Baseline design: 13 SEER, R-410A Hot/Dry designs Design 1: 1.4X Evap HX surface area Design 2: 1.4X Evap HX surface area; ECM Blower Motor Design 3: 1.4X Evap HX surface area; ECM Blower Motor; Rated Ducts Design SEER System Hot/Dry EER Out: 115 F In: 80 F/62 F Face Area Sq.ft. Flow CFM Evaporator Fan Power 115 F; 80/62 F Watts Evap Temp Out: 95 F In: 80 F/67 F Compressor Percent of Baseline Displacemen t Ducts Type / Ext. Static Inches H 2 O Baseline 13.1 7.5 5.0 1200 355 48 F - Typical / 0.5"@1200 CFM Design 1 13.8 8.0 7.2 1200 330 52 F 94% Typical / 0.5"@1200 CFM Design 2 14.6 8.4 7.2 1200 265 52 F 91% Typical / 0.5"@1200 CFM Design 3 15.4 9.2 7.2 1500 250 55 F 84% Rated / 0.15" fixed 4

Designs evaluated at multiple temperatures for purposes of modeling in a typical house Baseline and three Hot/Dry designs were simulated with the ORNL Heat Pump Design Model, Mark VI, at four sets of outdoor dry bulb/indoor wet bulb temperature conditions More efficient designs maintain their efficiency advantage regardless of temperature conditions Compressor downsized to match baseline capacity-- hot/dry design condition EER 17 16 15 14 13 12 11 10 9 8 7 85/62 85/67 85/72 95/62 95/67 95/72 105/62 105/67 105/72 115/62 115/67 115/72 Indoor Dry Bulb Temp = 80'F Very close to EER B (SEER) rating point Outdoor Dry Bulb / Indoor Wet Bulb Temperature Design 3 Design 2 Design 1 Base 5

Prototypical house chosen for two hot/dry locations: Fresno, CA and Phoenix, AZ California prototypical house for Fresno Fresno house modeled in Phoenix (only weather changed) Both locations modeled with DOE-2 Square footage: 2258 sq.ft. Number of floors: 2 Floor type: Slab-on-grade Exterior wall Area: 1584 sq.ft. Insulation: R-13 Ceiling insulation: R-30 Windows Area: 251 sq.ft. Window-to-Wall Ratio: 16% R-value: R-1.2 (double-glazing) 6

Designs yield both annual energy and peak demand savings in Fresno Fresno: Annual Energy Use Fresno: Peak Day in July Annual Energy Use (kwh/yr) 8000 7000 6000 5000 4000 3000 2000 1000 0 7639 7413 7188 6832 Base Design 1 Design 2 Design 3 Load (kw) 5 4 3 2 1 0 Base Design 1 Design 2 Design 3 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour 7

Designs yield both annual energy and peak demand savings in Phoenix Phoenix: Annual Energy Use Phoenix: Peak Day in August Annual Energy Use (kwh/yr) 14000 12000 10000 8000 6000 4000 2000 12342 11835 11357 10579 Load (kw) 6 5 4 3 2 1 Base Design 1 Design 2 Design 3 0 Base Design 1 Design 2 Design 3 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour 8

CEC-PIER Hot-Dry a/c Proof of Concept Project Proctor Engineering et al. have modified Keith Rice s Designs and built two early prototypes optimized for California a/c loads, one 3-ton residential split system, one 5-ton commercial package unit. Actual measurements to date support the calculations provided in earlier slides See http://www.hdac-des-pier.com/project.html 9

Residential electric utility tariffs used to calculate bills Fresno: Pacific Gas & Electric Co. Schedule E-1 Residential Service (Zone R) (Effective March 1, 2004) Monthly Summer Charges 0 to 534 kwh: 12.59 /kwh 534 to 694 kwh: 14.32 /kwh 694 to 1068 kwh: 18.15 /kwh 1068 to 1602 kwh: 21.43 /kwh Remaining kwh: 21.43 /kwh Monthly Winter Charges 0 to 387 kwh: 12.59 /kwh 387 to 503 kwh: 14.32 /kwh 503 to 774 kwh: 18.15 /kwh 774 to 1161 kwh: 21.43 /kwh Remaining kwh: 21.43 /kwh Fixed Charges Monthly Charge: $5.00 Phoenix: Arizona Public Service Co. Residential Service E-12 (Effective July 1, 2003) Monthly Summer Charges 0 to 400 kwh: 7.38 /kwh 400 to 800 kwh: 10.28 /kwh Remaining kwh: 11.99 /kwh Monthly Winter Charges All kwh: 7.39 /kwh Fixed Charges Basic Service Charge: $7.50 10

Time dependent valuation (TDV) prices are also used to calculate bills TDV prices are incorporated into California appliance standards (Title 20) and building standards (Title 24) TDV prices, or avoided costs, are independent of the idiosyncrasies of utility tariffs TDV prices incent efficient air conditioners 60.0 TDV: Climate Zone 13 (Fresno), August 6 50.0 TDV (cents/kwh) 40.0 30.0 20.0 10.0 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour 11

Time dependent valuation (TDV) prices vary over the year Although TDV prices in some hours exceed 50 /kwh, annual average TDV price equals 15 /kwh 60 TDV: Climate Zone 13 (Fresno), Annual 50 TDV (cents/kwh) 40 30 20 10 0 0 876 1752 2628 3504 4380 5256 6132 7008 7884 8760 Hour 12

Fresno A/C energy use can now be expressed as utility bills PG&E and TDV $1,600 $1,400 Fresno: Annual Utility Bill $1,506 $1,456 $1,407 Residential TDV $1,327 $1,200 Annual Bill $1,000 $800 $600 $967 $928 $890 $832 $400 $200 $0 Base Design 1 Design 2 Design 3 13

Phoenix A/C energy use can now be expressed as utility bills APSC and TDV $2,500 $2,000 Phoenix: Annual Utility Bill $2,401 $2,297 $2,199 Residential TDV $2,044 Annual Bill $1,500 $1,000 $1,280 $1,221 $1,167 $1,079 $500 $0 Base Design 1 Design 2 Design 3 14

Consumer price of more efficient designs increase with efficiency Manufacturer Cost Δ Consumer Price Compressor Evap Coil Evap Motor Total Δ Cost Δ Price Δ Ducts Δ Total Baseline $168 $113 $61 $342 - - - - Design 1 $158 $172 $61 $391 $49 $101 - $101 Design 2 $153 $172 $185 $510 $168 $348 - $348 Design 3 $141 $172 $185 $497 $155 $322 $500 $822 Manufacturer cost estimates from 2001 DOE Technical Support Document 15

Cost-effectiveness of designs based upon LCC savings and payback Life-cycle cost (LCC) is the sum of the total installed cost plus the present value of the lifetime operating cost savings For residential tariff calculations, present value of future operating cost savings calculated with a 5.6% real discount rate Equipment lifetime set to 18.4 years Future electricity price trends based upon DOE-EIA s 2004 Annual Energy Outlook Both the discount rate and lifetime are taken from DOE s central air conditioner rulemaking analysis Payback period is the increase in total installed cost divided by the annual operating cost savings 16

All designs provide both LCC savings and short payback periods in Fresno Life-Cycle Cost $25,000 $20,000 $15,000 $10,000 $5,000 Fresno: Life-Cycle Cost Residential TDV $21,091 $20,573 $20,213 $19,708 $14,021 $13,695 $13,708 $13,548 Payback Period (years) 8 7 6 5 4 3 2 1 Fresno: Payback Periods Residential TDV 5.8 3.5 2.6 2.0 7.0 4.6 $0 Base Design 1 Design 2 Design 3 0 Design 1 Design 2 Design 3 17

All designs provide both better LCC savings and shorter payback periods in Phoenix Life-Cycle Cost $35,000 $30,000 $25,000 $20,000 $15,000 $10,000 $5,000 Phoenix: Life-Cycle Cost $32,096 $30,917 $29,955 $17,436 $16,902 $16,740 $16,251 Residential TDV $28,527 Payback Period (years) 5 4 3 2 1 Phoenix: Payback Periods Residential TDV 3.7 1.8 1.7 1.0 4.5 2.3 $0 Base Design 1 Design 2 Design 3 0 Design 1 Design 2 Design 3 18

Cost of Conserved Energy (CEE) can also be used to evaluate designs! AC "CRR CCE = $! kwh per year CEE = Cost of Conserved Energy Δ$ AC = Consumer price increase due to hot/dry AC design CRR = Capital recovery rate; set at 10% per year ΔkWh per year = Annual energy savings due to hot/dry AC design TDV and CCE(cents/kWh) 60.0 50.0 40.0 30.0 20.0 10.0 0.0 TDV (CZ 13, Aug 6) comparison to Design CCEs TDV CCE Design 3 CCE Design 2 CCE Design 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour 19

Summary of Analysis All three Hot/Dry A/C designs developed by ORNL provide LCC savings and relatively short payback periods LCC savings range from: ~$300 to ~$1200 based on residential electric utility tariffs ~$500 to ~$3500 based on TDV prices Payback periods range from 2 to 7 years LCC savings and payback periods are relative to a 13 SEER baseline design To exploit full savings potential: Manufacturers need to offer equipment designed for Hot/Dry climates California needs to revise building standards to ensure good ducts 20