Iowa Public Building Benchmarking Introduction to the Public Website Presented by Xiaohui “Joe” Zhou, PhD, PE, Iowa Energy Center
Outline Introduction of Building Energy Benchmarking Basic Concepts and Terminologies Iowa Public Building Energy Benchmarking Public Site How to Interpret the Results
Introduction - Benchmarking Energy Benchmarking For cars we use: Miles per gallon For lighting efficiency (more accurately luminous efficacy): Lumens per Watt For buildings we use Energy Use Intensity (EUI): kBTU per square foot per year
Introduction - Benchmarking Building Energy Benchmarking Building Energy Benchmarking Methods Compare with similar buildings, within a portfolio, or nationally? • Compare to self in a baseline year? • Compare to an energy code-compliant building of the same size, • type, and function? Iowa Public Building Energy Benchmarking Does all three methods •
Introduction - Terminology Energy Use Intensity (EUI): • Total energy of all fuel sources consumed by the building in one year, converted to kBTU and divided by the total gross floor area of the building • Unit: kBTU/SF/yr ; • BTU: British Thermal Unit. A traditional unit of energy. A BTU represents the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. • 1 kBTU = 1000 BTU = 293 Watt-Hour = 0.293 kWH • 1 kWH = 3.412 kBTU
Introduction - Terminology Chicago Denver Minneapolis City • However, EUI alone is Climate Zone 5A 5B 6A not a reliable indicator Large Office 43 36 46 for building energy Medium Office 48 41 54 performance. Many Small Office 51 45 57 factors have impact: Warehouse 24 23 29 Stand-alone Retail 81 69 93 o Weather Strip Mall 85 72 99 o Building type Primary School 65 58 75 o Building function Secondary School 76 64 89 o Occupancy Supermarket 195 179 208 Quick Service Restaurant 657 604 713 Full Service Restaurant 527 481 570 Hospital 148 130 153 Outpatient Facility 271 271 280 Small Hotel 80 74 87 Large Hotel 138 131 150 Mid-Rise Apartment 47 41 54 * DOE Commercial Building Benchmarks – New Construction. EUIs (kBTU/sf/yr). October 2009
Introduction - Terminology Benchmarking EUI Building Energy Codes: minimum requirements for energy efficient • design and construction of new and retrofit buildings Benchmarking EUI: Predicted annual Energy Use using simulation based • on the energy-code compliant building with the same size, space types, occupancy, and local weather conditions Benchmarking Index Ratio Index Ratio = Actual EUI / Benchmarking EUI • Smaller the better. e.g., a 0.75 number means the building uses 25% • less energy than an energy-code compliant building. A 1.5 number means the building used 50% more.
Introduction - Basic Concept A building may have its own meters thus 1 site = 1 building, however… • Some buildings share 1 or more meters with other buildings, thus 1 site = • various buildings Each participating organization may have one or more sites • Site G G G Site E E G: Gas meter; E: Electric meter
Iowa Public Building Benchmarking 600 buildings (Phase II so far) 1200 buildings (Phase I)
Introduction – Public Site Sector Selection Menu Result Selection Tabs Result Window Expand Windows Result Map Window
How to Interpret the Results Sectors • 1: All Sectors • 2: Cities (default) • 3: Counties • 4: Public Schools • 5: Community Colleges • 6: Higher Education • 7: State Agencies Organizations within the same sector may be more comparable.
How to Interpret the Results Main Table – by EUI Rank or sort by average EUI for all completed buildings
How to Interpret the Results Rank or sort by Main Table – by Benchmark Benchmarking Index Ratio • Benchmark Star Ratings correspond to Index Ratio ranges
How to Interpret the Results Rank or sort by average Main Table – by Energy $/SF unit energy cost for all completed buildings
How to Interpret the Results Rank or sort by energy savings (MMBtu/yr) or Main Table – by Potential Savings cost savings ($/yr) for all completed buildings • For any organization that has benchmarking ratio > 0.85 MMBTU: 1 Million BTU = 1,000,000 BTU
How to Interpret the Results Main Table – by Freshness of Data Rank or sort by the “freshness” of utility data
How to Interpret the Results Map – sorted by EUI Result summary
How to Interpret the Results Help
How to Interpret the Results Summary In reviewing an organization’s results, first look at benchmarking • index ratio (and therefore benchmarking five-star rating) Then look at potential energy savings and cost savings • Look at energy $/SF • Freshness of data • Compare within the same sector • Note: This website is designed to inform the public about how Iowa public buildings perform and for organizations to make better informed decisions when doing energy efficiency work. All participating organizations have voluntarily started the process to measure their buildings’ performances. The Iowa public building benchmarking team fully appreciates their participation and co-operation.
More Questions? Xiaohui “Joe” Zhou, xhzhou@iastate.edu Katie Schmitt, katies@twgi.com
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