Efficient Low-Lift Cooling with Radiant Distribution, Thermal Storage and Variable-Speed Chiller Controls Srinivas Katipamula, Ph.D. Peter Armstrong, Ph.D., Weimin Wang, Ph.D., Nick Fernandez, Heejin Cho, Ph.D. 1 Clima 2010, May 10 th, 2010, Antalya, Turkey

Outline of Presentation Introduction to Low-Lift Cooling System Energy Savings Building prototypes Climate locations Simulation Grid U.S. National Technical Energy Savings Potential Economic Analysis – Simple Payback Calculations Conclusions and Future Work 2

Introduction to Low-Lift Cooling System 3

Low-Lift Cooling System 4 Peak-Shifting by Cooling at Night –Proven demand savings technology –Use building mass or thermal energy storage (TES) –Improves chiller load factor; milder condensing conditions (10-20 o F) Radiant Cooling Panels (RCP) and Dedicated Outside Air Supply (DOAS) –Emerging technology - Popular in Europe –65°F panels or slabs provide “cooling” instead of 50°F air –DOAS with enthalpy recovery for fresh air –Eliminates wasteful reheat; reduces fan power (80%) Low-Lift Vapor Compression Cooling Equipment –Combining low-lift chiller with RCP, TES and DOAS is a good match for new buildings –Designed for efficient part-load and low-lift operation due to variable speed compressors –Converts the favorable Exergy properties of DOAS/RCP and Peak- Shifting/TES into energy savings Add Integrate Sum of Energy Savings Greater than its Parts …Plus Comfort and Control Benefits Start with

Energy Savings Estimation Methodology 5

EnergyPlus to generate thermal loads (coil loads) Matlab component models to estimate the energy consumption of low-lift chiller, DOAS, fan and pump Per building energy savings were translated to national technical potential using new construction weights derived from McGraw Hill New Construction Database 6

Building Prototypes and Climate Locations for Low-Lift Analysis Building Types Office – small, medium and large Mercantile – Standalone retail and strip mall School – Primary and Secondary Schools Food Sales - supermarket Health Care – outpatient and Hospital Lodging – large hotel Warehouse – non- refrigerated warehouse Climate Locations Miami, FL Houston, TX Phoenix, AZ Atlanta, GA Los Angeles, CA Las Vegas, NV San Francisco, CA Baltimore, MD Albuquerque, NM Seattle, WA Chicago, IL Denver, CO Minneapolis, MN Helena, MT Duluth, MN Fairbanks, AK 7

Standard vs. High Performance Buildings (a) Because the values vary by climate locations, the values are not listed in this table (b) Completely shade the solar direct beam (c) Load density during hours of the highest loads (d) Total HVAC fan power divided by total HVAC fan flow rate 8 Component Performance Levels to be Analyzed Component Baseline High Performance Wall-Roof U-Factor (a) 4/9 th of Window U-Factor and SHGC (a) 4/9 th of Window-to-Wall-Ratio40%20%+Shading (b) Lighting and Plug Load (c) Power Density (W/sf) Fan Power (W/scfm) (d)

Analysis Grid for Low-Lift Analysis 12 Building Types 16 Climate Locations 2 Building Performance Levels and 3 System Combinations ASHRAE Standard (referred to as Standard) High Performance (approximately 50% lower than Standard) With economizer, without economizer and energy recovery ventilation 8 Different Low-Lift HVAC Combinations 1152 EnergyPlus Simulation 9,216 Matlab Simulations 9

Summary of Energy Savings 10

Summary of Low-Lift Combinations Case 0: Baseline – EnergyPlus Benchmark Case 1: 2-Speed Chiller, CAV/VAV Case 2: Variable-Speed Chiller, CAV/VAV Case 3: 2-Speed Chiller, CAV/VAV, TES Case 4: 2-Speed Chiller, CAV/VAV,TES Case 5: 2-Speed Chiller, RCP/DOAS Case 6: Variable-Speed Chiller, RCP/DOAS Case 7: 2-Speed Chiller, RCP/DOAS, TES Case 8: Variable-Speed Chiller, RCP/DOAS, TES 11

National Technical Potential Savings 12

Comparison of Annual Energy Consumption – Standard Performance Building 13

Range of Energy Reduction (Case 0 – Case 8) 14

Range of Energy Reduction (Case 1 – Case 8) 15

National Technical Potential Estimation Methodology 16 Per Building Energy Savings Number of New Buildings Built in a Year By Climate Location National Savings

Summary of Annual National Technical Site Electricity Savings Potential 17 Low-Lift Cooling System – Case 8 (assuming 100% Penetration) in Comparison to Case 0 Low-Lift Cooling System – Case 8 (assuming 100% Penetration) in Comparison to Case 1

Comparison of Annual National Technical Site Electricity Savings Potential 18 For Various Low-Lift Cooling Design Option Set (assuming 100% Penetration) in Comparison to Case 0

Comparison of Annual National Technical Site Electricity Savings Potential 19 For Various Low-Lift Cooling Design Option Set (assuming 100% Penetration) in Comparison to Case 1

Economic Analysis – Simple Payback 20

Incremental Cost of Low-Lift System by Climate Location 21 Cost Index Cost

Energy Cost Savings by Building Type in each Climate Location 22

Simple Payback by Building Type for each Climate Location 23

Future Planned Activities 24

Planned Activities Identification and Evaluation of Potential Alternate Low-Lift Options Development and Testing (simulated environment) of Predictive Control Algorithm Testing of Predictive Control Algorithm in Real Building Develop a Specification to Integrate the Predictive Controller into EnergyPlus 25

Questions? 26