ASHRAE Journal - February 2011 - 86

commissioning	

capturing the Potential
By Evan mills, Ph.D.

T

he	emerging	practice	of	building	commissioning	is	a	particularly	 potent	means	of	increasing	energy	efficiency.	Although	commission-

ing	has	earned	increased	recognition	in	recent	years—even	a	toehold	 in	Wikipedia—it	remains	an	enigmatic	practice	whose	visibility	considerably	lags	its	potential.	
Quality assurance and optimization are essential elements of any serious technological endeavor, including efforts to improve energy efficiency. Commissioning is an important tool in this respect. The aim of commissioning new buildings is to ensure that they deliver—if not exceed—the performance and energy savings promised by their design. When applied to existing buildings, one-time or repeated commissioning (often called retrocommissioning) identifies the almost inevitable drift in energy performance and puts the building back on course, often surpassing the original design intent. In both contexts, commissioning is a systematic, forensic approach to improving performance, rather than a discrete technology. Specific deficiencies identified and corrected through the commissioning process include problems such as simultaneous heating and cooling, inefficient thermal distribution layout, miscalibrated or otherwise malfunctioning energy management controls and sensors, defeated efficiency features (e.g., variable speed drives locked at full speed), leaky air-distribution systems, inappropriate setpoints and control sequences, and oversized equipment. These kinds of problems collectively waste several tens of billions of dollars in energy each year
86	 ASHRAE	Journal	

in the U.S. alone, while compromising occupant comfort, health, and safety. In an ideal world, these issues would be caught during the original design or corrected by routine operations and maintenance, but that is all too rare in practice. Energy-wasting deficiencies are often invisible to the casual observer, and unfortunately also to building designers, operators, owners, and all but the most attuned engineers. Commissioning can reduce the carbon footprint of unremarkable buildings, or ensure the success of ones deliberately designed to push the limits of efficiency. Uncertainties about cost and costeffectiveness are a key barrier to the growth of the commissioning industry. Building owners understandably ask why they need to pay “extra” for remediation of less-than-best practices. Program designers, utility regulators, and other policymakers must all justify investments in commissioning. In an effort to provide better information to all players, the Lawrence Berkeley National Laboratory (LBNL) has assembled the world’s largest compilation and meta-analysis of commissioning experience in actual commercial buildings. The database has grown to 643 buildings (all located in the U.S., and spanning 26 states). Projects represent 100 million ft2
ashrae.org	

(9 290 300 m2) of floorspace, $43 million in commissioning expenditures, and the work of 37 commissioning providers. The recorded cases of new-construction commissioning took place in buildings representing $2.2 billion in total construction costs. The costs include labor and materials for external commissioning agents, plus other trades and supporting in-house staff, and are limited to commissioning activities targeting energy savings, as distinct from other systems such as safety and security. The results are compelling. The median cost to deliver commissioning was $0.30/ ft2 ($3/m2) (in 2009 dollars) for existing buildings and $1.16/ft2 ($12/m2) for new construction (or 0.4% of the overall construction cost). More than 10,000 specific deficiencies were identified across one-third of the sample for which data were available. Correcting these problems resulted in 16% median whole-building energy savings in existing buildings and 13% in new construction, with payback times of 1.1 years and 4.2 years, respectively. Median benefit-cost ratios of 4.5 and 1.1, and cash-on-cash returns (a common statistic used in the real estate industry) of 91% and 23% were achieved. Projects with a relatively thorough approach to commissioning (e.g., incorporating benchmarking, design intent documentation, construction observation, functional testing, acceptance testing, operator training, and calibrated simulation) attained nearly twice the overall median level of savings and five-times the savings of the least-thorough projects. It is noteworthy that virtually all existingbuilding projects were cost-effective by each metric (e.g., paybacks of 0.4 years for the upper quartile and 2.4 years for the lower quartile), as were the majority
	 February	 2011



ASHRAE Journal - February 2011

Table of Contents for the Digital Edition of ASHRAE Journal - February 2011

ASHRAE Journal - February 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Thermal Coupling of Cooling and Heating Systems
10 Common Problems in Energy Audits
Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
A Guide to Wireless Technologies
Building Sciences
Solar NZEB Project
Emerging Technologies
People
Special Section
InfoCenter
Commissioning
Products
Washington Report
Classified Advertising
Advertisers Index
ASHRAE Journal - February 2011 - ASHRAE Journal - February 2011
ASHRAE Journal - February 2011 - Cover2
ASHRAE Journal - February 2011 - 1
ASHRAE Journal - February 2011 - 2
ASHRAE Journal - February 2011 - Contents
ASHRAE Journal - February 2011 - Commentary
ASHRAE Journal - February 2011 - 5
ASHRAE Journal - February 2011 - Industry News
ASHRAE Journal - February 2011 - 7
ASHRAE Journal - February 2011 - Letters
ASHRAE Journal - February 2011 - 9
ASHRAE Journal - February 2011 - 10
ASHRAE Journal - February 2011 - 11
ASHRAE Journal - February 2011 - 12
ASHRAE Journal - February 2011 - 13
ASHRAE Journal - February 2011 - 14
ASHRAE Journal - February 2011 - 15
ASHRAE Journal - February 2011 - Meetings and Shows
ASHRAE Journal - February 2011 - 17
ASHRAE Journal - February 2011 - Thermal Coupling of Cooling and Heating Systems
ASHRAE Journal - February 2011 - 19
ASHRAE Journal - February 2011 - 20
ASHRAE Journal - February 2011 - 21
ASHRAE Journal - February 2011 - 22
ASHRAE Journal - February 2011 - 23
ASHRAE Journal - February 2011 - 24
ASHRAE Journal - February 2011 - 25
ASHRAE Journal - February 2011 - 10 Common Problems in Energy Audits
ASHRAE Journal - February 2011 - 27
ASHRAE Journal - February 2011 - 28
ASHRAE Journal - February 2011 - 29
ASHRAE Journal - February 2011 - 30
ASHRAE Journal - February 2011 - 31
ASHRAE Journal - February 2011 - 32
ASHRAE Journal - February 2011 - 33
ASHRAE Journal - February 2011 - Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
ASHRAE Journal - February 2011 - 35
ASHRAE Journal - February 2011 - 36
ASHRAE Journal - February 2011 - 37
ASHRAE Journal - February 2011 - 38
ASHRAE Journal - February 2011 - 39
ASHRAE Journal - February 2011 - 40
ASHRAE Journal - February 2011 - 41
ASHRAE Journal - February 2011 - 42
ASHRAE Journal - February 2011 - 43
ASHRAE Journal - February 2011 - A Guide to Wireless Technologies
ASHRAE Journal - February 2011 - 45
ASHRAE Journal - February 2011 - 46
ASHRAE Journal - February 2011 - 47
ASHRAE Journal - February 2011 - 48
ASHRAE Journal - February 2011 - 49
ASHRAE Journal - February 2011 - Building Sciences
ASHRAE Journal - February 2011 - 51
ASHRAE Journal - February 2011 - 52
ASHRAE Journal - February 2011 - 53
ASHRAE Journal - February 2011 - 54
ASHRAE Journal - February 2011 - 55
ASHRAE Journal - February 2011 - 56
ASHRAE Journal - February 2011 - 57
ASHRAE Journal - February 2011 - 58
ASHRAE Journal - February 2011 - 59
ASHRAE Journal - February 2011 - 60
ASHRAE Journal - February 2011 - 61
ASHRAE Journal - February 2011 - Solar NZEB Project
ASHRAE Journal - February 2011 - 63
ASHRAE Journal - February 2011 - 64
ASHRAE Journal - February 2011 - 65
ASHRAE Journal - February 2011 - 66
ASHRAE Journal - February 2011 - 67
ASHRAE Journal - February 2011 - 68
ASHRAE Journal - February 2011 - 69
ASHRAE Journal - February 2011 - Emerging Technologies
ASHRAE Journal - February 2011 - 71
ASHRAE Journal - February 2011 - 72
ASHRAE Journal - February 2011 - 73
ASHRAE Journal - February 2011 - 74
ASHRAE Journal - February 2011 - 75
ASHRAE Journal - February 2011 - People
ASHRAE Journal - February 2011 - 77
ASHRAE Journal - February 2011 - InfoCenter
ASHRAE Journal - February 2011 - 79
ASHRAE Journal - February 2011 - 80
ASHRAE Journal - February 2011 - 81
ASHRAE Journal - February 2011 - 82
ASHRAE Journal - February 2011 - 83
ASHRAE Journal - February 2011 - 84
ASHRAE Journal - February 2011 - 85
ASHRAE Journal - February 2011 - Commissioning
ASHRAE Journal - February 2011 - 87
ASHRAE Journal - February 2011 - 88
ASHRAE Journal - February 2011 - 89
ASHRAE Journal - February 2011 - 90
ASHRAE Journal - February 2011 - Products
ASHRAE Journal - February 2011 - Washington Report
ASHRAE Journal - February 2011 - Classified Advertising
ASHRAE Journal - February 2011 - 94
ASHRAE Journal - February 2011 - 95
ASHRAE Journal - February 2011 - Advertisers Index
ASHRAE Journal - February 2011 - Cover3
ASHRAE Journal - February 2011 - Cover4
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