1. Energy Auditing Techniques for Small Commercial Facilities
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Sean Harleman, kW Engineering

2. HVAC Systems Directions:
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Introduction to Energy Audits, Pre-Audit Assessment, Lighting Systems, Motor Systems, Commercial Refrigeration Systems, Commercial Kitchen and Food Service Systems, Natural Gas Fired Equipment, HVAC Systems, Envelop Systems, Misc Systems, Demand Response, Financial Calculations, or Renewables.
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3. Energy Auditing Techniques
Learning Objectives
Recognize common system types and controls
Understand economizers and outside air
Gather useful nameplate data
Provide recommendations for replacements
Do some simple energy savings calculations
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Energy Auditing Techniques

4. Energy Auditor Role and Activities
Basic
Inspect HVAC equipment
Record nameplate information
Review equipment operating schedules and controls
Develop a list of energy efficiency measures (EEMs)
Present EEMs, savings, incentives, and costs to the client
Advanced
Above items plus:
Log existing power use (status, amps, or kW)
Log economizer operation (OAT, MAT, etc.)
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Energy Auditing Techniques

5. Energy Auditing Techniques
HVAC Fundamentals
Heating
Offset heat that is lost to the environment
Temper ventilation air
Ventilating
Provide fresh air to building occupants
Air Conditioning (or Cooling)
Offset heat that gained from the environment
Offset heat generated internally
Control interior moisture (Relative Humidity)
Energy Auditing Techniques

6. Why is HVAC Important? CA Commercial Sector Electricity Use
California Commercial End Use Survey, Itron, CEC
Energy Auditing Techniques

7. Primary Purposes of HVAC
Comfort for occupants (ASHRAE 55)
Temperature
Humidity
Air movement
Fresh air (ASHRAE 62.1 & T24)
We need about 15 cfm per person (occupancy)
Remove dust, pollutants, contaminants & “bio-effluents”
Energy Auditing Techniques

8. Heat Sources, Sinks & Paths
Envelope
Solar
Conduction
Ventilation Air
Required for IAQ
Internal Loads
Lighting
Computers
Equipment
People
Energy Auditing Techniques

9. Energy Auditing Techniques
What is a HVAC Zone?
A discreet physical area that is conditioned by an HVAC system
Heat enters/leaves a zone through Conduction, Convection and Radiation
Borders on zones are not always clear, obvious, or tangible
Distinct zones in HVAC system marked by separate thermostats
Energy Auditing Techniques

10. Single Zone HVAC System
Energy Auditing Techniques

11. Primary Cooling Technologies
Mechanical Cooling
Unitary equipment uses a direct expansion (DX) cooling coil
accounts for ≈ 67% of all commercial and ≈ 90% of all small commercial
this will be our focus today
Chilled water systems used in large buildings
en.wikipedia.org
Energy Auditing Techniques

12. Unitary HVAC Equipment
Unitary refers to equipment where components are matched and rated together. These components include a compressor, condenser, evaporator and fan.
Unitary equipment has two main classes: Packaged and Split-System
Packaged equipment houses all components in the same enclosure
Split-Systems have the compressor & condenser in one enclosure and the evaporator and fan in another, connected by refrigeration tubing
Units can be cooling only or cooling with heating
All units circulate air, most provide ventilation
Energy Auditing Techniques

13. Unitary Equipment Identification
Packaged Unit
All components contained in one location
Ventilation is introduced through the unit
Heating is supplied by a gas furnace, heat pump, electric resistance or a hot water coil
Energy Auditing Techniques

14. Packaged Unit Components
Economizer EA OA
Cooling Coils SA
Heating Coils
Filter
Supply Fan
Condenser Fan and Coils RA T
Controls
Thermostat
Economizer is FREE Cooling
Discuss need for barometric relief (weighted) damper at the exhaust air outlet.
Fresh air enters at OA.
Supply air fan may be “draw through” or “blow though”.
SA is supply air or discharge air.
Compressor
Packaged Unit
Building
Energy Auditing Techniques

15. Packaged With Horizontal Discharge
Energy Auditing Techniques

16. Packaged With Vertical Discharge
Energy Auditing Techniques

17. Unitary Equipment Identification
Split-System
Compressor Component Only
No Ventilation provided by unit
Only heating is heat pump
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18. Energy Auditing Techniques
Split-System
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19. Split-System Examples
Energy Auditing Techniques

20. Split-System Examples
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21. Energy Auditing Techniques
Unclear on the concept
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22. Primary Cooling Technologies
Mechanical cooling (e.g. DX) energy use can be reduced through the use of economizers and evaporative cooling
HVAC equipment is sized for design day loads, but operates the majority of the time under part load (~30-50% average is typical)
Energy Auditing Techniques

23. Energy Auditing Techniques
Economizers
The economizer cycle refers to using controls and dampers to make use of outside air for “free” cooling when it makes sense
Controls used to bring in outside air instead of return air
An “economizer” is generally not a single piece of equipment, although people may refer to it as such
Energy Auditing Techniques

24. Economizer Offsetting All Cooling
Energy Auditing Techniques

25. Reduced Mechanical Cooling
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26. Energy Auditing Techniques
Air Side Economizer
Easy to show it’s not working, harder to show that it is working
Spot checks not conclusive; must trend data over time
Is the economizer bringing in 100% outside air when appropriate?
Is the system always providing minimum ventilation air?
80F is the return air temperature
Mixed and outside should match between 45F and 55F on all economizers
should track up to 78F on integrated economizers
Energy Auditing Techniques

27. Economizer Expected Performance
Expected Economizer Operation 80
Minimum outside air 75 70 65
Outside Air Temperature
Temperature
Return Air Temperature 60
Mixed Air Temperature 55
100% Outside air
Supply Air Temperature
OA and Mixed air track from 60F to 74F
system shuts down to a minimum at 74F but mixed air continues to warm as OA rises due to minimum ventilation requirement
shuts down to maintain 60F supply air from cold OA (below 60F) 50
Mixed return and outside air 45 40 1 2 3 4 5 6 7 8 9 10
Noon 11 12 13 14 15 16 17 18 19
Midnight 20 21 22 23 24
Time
Energy Auditing Techniques

28. Economizer Expected Performance
Data taken from a study in Southern California
Building type is Small Office
Percent Loaded is calculated as Compressor Run Hours / by Total Cooling Hours
OA and Mixed air track from 60F to 74F
system shuts down to a minimum at 74F but mixed air continues to warm as OA rises due to minimum ventilation requirement
shuts down to maintain 60F supply air from cold OA (below 60F)
Energy Auditing Techniques

29. Economizers: Implementation
Assess economizer operation by observing damper positions for various ambient conditions
Use temperature data loggers to better estimate economizer performance
Consider add-on economizer kits for existing units with failed economizers
Check for adequate relief for outside air
Energy Auditing Techniques

30. Energy Auditing Techniques
Evaporative Cooling
Cools air via evaporation of water
Direct evaporative coolers draw air through evaporative media lowering the temperature and increasing humidity
Indirect evaporative coolers use a heat exchanger to reduce the air temperature without increasing humidity; less effective
Dampers controlled by economizer: OA, RA & EA.
55 degrees is the supply air temperature
80 degrees is the return air temperature
For100% economizer cooling:
Economizer control opens damper (cycles) as if it is the first stage of cooling.
Minimum ventilation is about 15% (w/ operable windows value can be lower?)
For Partial cooling high limits apply:
single set-point uses an assumed return air temperature (this is typical case)
differential uses two sensors: OA & RA and chooses the cooler:
if OA is cooler unit brings in 100% OA
if RA is cooler unit brings in 85% RA and 15% OA
Needs to be maintained annually.
Energy Auditing Techniques

31. Direct Evaporative Cooling
This image has been (or is hereby) released into the public domain by its creator, Buster2058. This applies worldwide.
Energy Auditing Techniques

32. Evaporative Cooling: Implementation
Best when high percentage of outside air is required
Supply air temperature limited by ambient conditions
Direct evaporative cooling is best suited for areas where high humidity won’t cause problems
Indirect evaporative cooling can be used when humidity needs to be controlled or mechanical cooling will also be used
Direct Evaporative Cooler
Energy Auditing Techniques

33. Primary Heating Technologies
Gas Furnaces are the most common source for heat in small commercial applications
Range of efficiencies available
Forced & Induced draft
Electric Heat Pumps provide both heating and cooling
Air source
Water Source
Ground Coupled
Electric Resistance Heat Strips can be convenient if natural gas is limited or combustion exhaust is an issue, but Heat pumps are more energy efficient
Hot water or Steam coils can also be used, but are generally found in larger systems or systems with many zones
highperformancehvac.com
Energy Auditing Techniques

34. Energy Auditing Techniques
Air Source Heat Pump
Utilizes same vapor compression refrigeration cycle, only now the condenser can be used to add heat to the space
Energy Auditing Techniques

35. Air Source Heat Pump Energy Auditing Techniques
oee.nrcan.gc.ca/publications/infosource/pub/h...
Energy Auditing Techniques

36. Air Source Heat Pump Energy Auditing Techniques
oee.nrcan.gc.ca/publications/infosource/pub/h...
Energy Auditing Techniques

37. Energy Auditing Techniques
Air Source Heat Pump
Use air as heat sink
Therefore: Efficiency depends on air temperatures (minimum outside operating temperature is ~ 17 °F)
Typically smaller systems / single zone
Best applicability: mild climates
SEERs range from 8 to 16
Title 20 Sets minimum standards by size
Also:
Water Source
Ground Coupled
Energy Auditing Techniques

38. Field Identification of HVAC Zones
Ask facility staff/engineer
Review as-built mechanical drawings
Inventory the number of thermostats and HVAC units
Observe placement of units to thermostats
Last resort: go after hours and observe response to changed setpoints
Energy Auditing Techniques

39. Unitary HVAC Nameplate
Brand/Model #
Age
Voltage/Amperage/kW
Other information:
Rated efficiency
Heating/cooling capacity
Air flow rate
Liquid flow rate
Pressure rise
Refrigerant
Lighting retrofit
Optimized “Free” cooling
Notice consistent increases June-September (or January lows)
Energy Auditing Techniques

40. It’s not always easy to get the size
Energy Auditing Techniques

41. It’s not always easy to get the size
Energy Auditing Techniques

42. Reinforcement Activity
HVAC system exercise…
Why are we here?
“Packaged units represent cooling for 49% of commercial buildings space”
Esource
Energy Auditing Techniques

43. Energy Efficiency Opportunities
Retrofits
High Efficiency Units
Evaporative Cooling
Controls
Scheduling / reduce operating hours
Programmable thermostats
Economizer operation
Demand control ventilation
Operations
Reduce cooling loads
Keep units maintained
Energy Auditing Techniques

44. High Efficiency Replacements
Package unit replacement isn’t generally cost effective on energy savings alone
So where are the opportunities?
Older units
Early retirement
New additions
How do we promote it?
Comfort
Reliability
Reduced O&M Costs
Energy Auditing Techniques

45. What to specify: Unitary AC and HP
For larger units, use Consortium for Energy Efficiency (CEE) guidelines (
Specify Tier 1 or 2 Efficiency level
Energy Auditing Techniques

46. What to specify: Unitary AC
© 2009 Consortium for Energy Efficiency, Inc. All rights reserved.
Energy Auditing Techniques

47. What to specify: Heat pumps
© 2009 Consortium for Energy Efficiency, Inc. All rights reserved.
Energy Auditing Techniques

48. Unitary HVAC: Calculations
Average Demand
kW = (Cooling CapacitykBtu/h) / (SEER)
Annual Energy Use
kWh/yr = (kW) * (hours per year)
Energy Auditing Techniques 48

49. Evaporative Pre-cooling
Lower head pressure by pre-cooling condenser air by direct evaporation
New units use microprocessor controls to minimize excess water
Water off for outside air temps less than 70°F
Evaporative pre-cooling is available as add-on kit to fit many unitary systems
Energy Auditing Techniques

50. Evaporative Pre-cooler Details
Energy Auditing Techniques

51. Evaporative Pre-cooler Details
Energy Auditing Techniques

52. Evaporative Pre-Cooling
This data from the Baypoint McDonalds shows that the evaporative pre-cooler operates when the OA temperature is above 75F. It clearly drops the temperature of the air as it exits the media.
Delta T as large as 15F
Energy Auditing Techniques

53. Evaporative Pre-cooler
Energy Auditing Techniques

54. Energy Auditing Techniques
Control Measures
On/off
Setbacks
Demand Control Ventilation
Energy Auditing Techniques

55. The Opportunity: Controls
General Concepts
Controls are generally the most cost effective of EEMs
Whatever doesn’t have controls probably needs it
Controls reduce opportunity for human “enhancements”
Limit hours of operation
Use to maximize system efficiencies
Energy Auditing Techniques

56. Energy Auditing Techniques
Scheduling
Mechanical Time Clocks
Energy Auditing Techniques

57. Energy Auditing Techniques
Commissioning is key
Even with simple equipment
Energy Auditing Techniques

58. Setbacks and Programmable Thermostats
Install Programmable Thermostats on all units
Scroll through settings during audit
Energy Auditing Techniques

59. Energy Auditing Techniques
Where there’s a will…
Energy Auditing Techniques

60. Setback Thermostats / Scheduling
Pitfalls
Need to be set correctly, not in “hold” mode
Persistence: document with a system manual how things are intended to work
Savings
Range widely depending on occupancy and use. Typical is 5% to 50%.
Demand savings are minimal
Non-Energy Benefits
Reduced wear on equipment
Energy Auditing Techniques

61. Web-enabled Thermostats
Web-based now available
About $170 to $300 each
Include ability to monitor remotely
Energy Auditing Techniques

62. Energy Auditing Techniques
For Classroom Control
Occupancy-based HVAC controls e.g. Bard CS2000 Energy Monitor
“Learns” occupancy patterns
No programming required
Can control lighting too
Outside air off when unoccupied
Energy Auditing Techniques

63. Demand Control Ventilation (DCV)
Primary purpose of HVAC is to provide adequate ventilation
Basic method has been to provide sufficient ventilation for design conditions at all times
DCV provides sufficient ventilation based on actual occupancy, rather than worst case
Requires continuous monitoring of CO2 as proxy for occupancy
Energy Auditing Techniques

64. DCV: CO2 and Ventilation Rates
Energy Auditing Techniques

65. Energy Auditing Techniques
DCV: Implementation
All major controls companies support
Best practice is to measure outside air and indoor air CO2 concentrations
If only indoor concentrations monitored, typical outside CO2 concentration is 400 ppm
Controls typically set to introduce OA when indoor concentration is about 500 ppm higher than outside (T-24 requires 600 or better)
DCV should be overridden when system in economizer mode
Commission to ensure ventilation rates are not compromised
Select equipment that automates building purge for overnight buildup of contaminants
Energy Auditing Techniques

66. Load Shifting for Small Commercial
“Ice Bear” makes ice at night for use the next day
Thermal Energy Storage
Capacity = 5 tons
Storage = 30 tonhrs
Primary savings are in cost of energy due to load shifting
Peak kW cost savings
May have small energy savings too, depending…
Energy Auditing Techniques

67. Ice Bear Installations
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68. Energy Auditing Techniques
Ice Bear Performance
Energy Auditing Techniques

69. Operations and Maintenance
Commissioning: check set points, schedules and resets
Check for controls overrides (e.g. bypassed time-clocks)
Filter changes for IAQ
Check fixed damper and minimum damper positions
Adjust/tighten/replace belts
Lubricate rotary equipment
Energy Auditing Techniques

70. Operations and Maintenance (cont.)
Clean condenser coils
Clean evaporator coils
Insulate suction lines
Check refrigerant charge
Check thermostat/sensor calibration
Insulate/seal ductwork
Energy Auditing Techniques

71. O&M horrors from HVACfun.com
Energy Auditing Techniques

72. Small HVAC: Frequent Issues
PIER Buildings Program Design Guide: Big Savings on Small HVAC Systems
Energy Auditing Techniques

73. Reinforcement Activity
HVAC calculation system exercise…
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74. Energy Auditing Techniques
Key Points to Remember
Economizers fail frequently and make a big difference in CA climates
HVAC units are sized for design-day conditions, but typically operate at 40-50% load
Calculating unitary HVAC annual energy use:
Energy (kWh/yr ) = [Capacity (kBtu/h) *hours (hr)] / SEER
Evaporative pre-cooling can yield big savings in dry climates
Record the entire model number from HVAC units
DCV provides savings for building with variable occupancies
Energy Auditing Techniques

75. References and Resources
PG&E
Database for Energy Efficiency Resources
CEC Guide to Preparing Feasibility Studies for Energy Efficiency Projects
Consortium for Energy Efficiency(guidelines for specifying EERs & rough costs/savings)
Energy Design Resources
Washington State University (calculators & other resources)
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Energy Auditing Techniques

76. Course Tracker Please take a moment to fill out your
Course Tracker excel sheet.
Directions:
-At the end of each section please remind the learners to fill out the Course Tracker excel sheet.
Give the learners an average of 2-3 minutes to fill out the tracker in order to help them capture their knowledge retention during class.
-The goal of this Course Tracker learning tool is to provide the learner the opportunity for self assessment of knowledge and documentation of questions at the end of each section. We hope that students will utilize this tool to help them assess what they know and what they may need to brush up on.
Energy Auditing Techniques

77. Energy Auditing Techniques
What is that?
1. Split - condenser
2. Packaged unit
3. Exhaust fan
4. Split - evaporator A.
Exhaust fan B.
Packaged Unit C.
Split - evaporator D.
Split - condenser
Energy Auditing Techniques

78. Model number: DPS-007-AHCY3
1. Cooling capacity:
7.5 tons
3. Line voltage:
230
2. EER:
High? Need more info
4. Heating type:
None
Energy Auditing Techniques

79. Energy Auditing Techniques
Appendix
Energy Auditing Techniques

80. Energy Auditing Techniques
VFD’s for Fans
Many systems use variable flow air distribution
Fan power laws dictate that power is roughly proportional to the flow rate cubed
VFD quality/reliability have improved greatly over time
VFD costs have dropped significantly with wider adoption
Now required by code for many applications in new construction
Energy Auditing Techniques

81. Why Fans with VFD’s Save Energy
This relationships between fan energy and fan flow are taken from the California Energy Commission Guide to Preparing Feasibility Studies and the 1998 Nonresidential ACM Approval Manual. Note that a typical system curve, DOE2 default, is assumed and these relationships are not applicable to all systems.
Energy Auditing Techniques

82. Energy Auditing Techniques
A Note on IPLV
IPLV is being replaced by IEER
Integrated Energy Efficiency Ratio (IEER)
IEER Used for unitary equipment ≥ 65 kBtu/h
AHRI is dropping use of IPLV because it did not accurately represent efficiencies for units with multi-stage compressors
AHRI Standard 340/ defines IEER as "a single number figure of merit expressing cooling part-load EER…”
Incorporated by addendum into ASHRAE
Not yet adopted by CEE, but soon
Energy Auditing Techniques

83. Energy Auditing Techniques
A Note on IPLV
Source:
Energy Auditing Techniques

84. Energy Auditing Techniques
DCV Savings
PIER Buildings Program Design Guide: Commercial Buildings Breathe Right with Demand-Controlled Ventilation
Energy Auditing Techniques

85. Energy Auditing Techniques
DCV Savings
Case studies show real energy savings with payback periods of 2 years or less
PIER Buildings Program Design Guide: Commercial Buildings Breathe Right with Demand-Controlled Ventilation
Energy Auditing Techniques

86. Water-source Heat Pumps
AKA “California Heat Pump” system
Uses water loop as heat sink
Requires supplemental heat rejection/supply
Cooling mode: rejects heat water loop
Heating mode: absorbs heat from water loop
Efficiency depends water loop temperatures
Typically mid-sized commercial systems / multiple zone
Best applicability: mild climates
Title 20 Sets minimum standards by size
McQuay Water Source Heat Pump Design Manual, C:330-1
Energy Auditing Techniques

87. Water-source Heat Pump Configuration
McQuay Water Source Heat Pump Design Manual, C:330-1
Energy Auditing Techniques

88. Equipment Efficiencies
Efficiency: Ratios developed to represent equipment ability to transfer or generate heat relative to the input energy required by that equipment
COP - Coefficient of Performance (unit less) What you get divided by what you pay for (in same units)
EER - Energy Efficiency Ratio (BTU/Watt-hrs) Fully loaded unit output / electrical input
SEER - Seasonal Energy Efficiency Ratio (BTU/Watt-hrs) Average output over a range of conditions / Electrical input
IPLV - Integrated Part Load Value (units vary) Weighted average at four part load conditions
HSPF - Heating Seasonal Performance Factor (BTU/Watt-hrs) Similar to SEER (same units) but for Heat Pump heating
AFUE - Annual Fuel Utilization Efficiency (%) Efficiency of gas furnaces and small boilers measured as the useful energy output divided by the input ή
Energy Auditing Techniques

89. Equipment Efficiencies
Energy Auditing Techniques

90. Energy Auditing Techniques
Units
Energy
Btu = Raises the temperature of 1 pound of water 1 degree Fahrenheit under standard conditions
Watt-Hour = Btu
kilowatt-hr = 1000 Watt-hours = 1 kWh
100,000 Btu = 100 kBTU = 1 therm
Rates (units of energy per time)
Watt = Btu/h (Btu’s per hour)
kilowatt = 1000 Watts = 1 kW
Energy Auditing Techniques

91. Energy Auditing Techniques
Handy Equations
Motor Draw
kWh = (hp)(0.746 kW/hp)(%Loaded)(hours)/Efficiency
kWh = (FLA)(Volts)(PF)(%Loaded)(hours)(Phase^½)
Conduction
Btu/h = (U-Value)(Area in sq ft)(Toutside-Tinside)
Surface heat gain/loss due to Convection & Radiation
Ventilation / Infiltration
Btu/h = (1.085)(CFM)(Toutside-Tinside)
Radiation
Btu/h = Assess qualitatively
Energy Auditing Techniques

92. Energy Auditing Techniques
More Handy Equations
Efficiency Conversions
kW/ton = 12 / EER
COP = EER / 3.412
COP = / (kW/ton)
Heat Transfer in Water
Capacity (kBTUh) = GPM * ΔT / 2
Power from hp
Power (kW) = * Power (hp)
Pump power
Water Power (hp) = (ft of head) * (GPM) / 3960
Pump Power = Water Power / [Pump eff * Motor eff]
Fan power
Fan Power (hp) = (cfm)*(SP) / [6354*ήfan* ήmotor]
Energy Auditing Techniques

93. Estimating Savings – Billing Data
Estimate amount of bill dedicated to air conditioning
Estimate the average efficiency of the existing equipment - SEER
Select new efficiency based on available equipment
Estimate savings as: or
Energy Auditing Techniques

94. Energy Auditing Techniques
Estimating Savings
Simplified Full Load Hour Calculation
Bin Simulation
SPC Software
PGE.COM/SPC
Order CD
Energy Auditing Techniques

95. Example Calculation: The Problem
Existing 5 ton air conditioner is on 24/7
Site is Sunnyvale, CA
EER is 10.0
Furnace is 80% efficient
Office environment with fan in “on” position (i.e. not “auto”)
Propose to schedule M-F, 7 AM to 6 PM
Energy Auditing Techniques

96. Energy Auditing Techniques
Here’s the nameplate
Energy Auditing Techniques

97. Example Calculation: Scheduling RTUs
Energy Savings from scheduling RTUs off consist primarily of two parts:
Reduced fan energy savings
Reduced ventilation loads
No simple way to take credit for transient effects
Energy Auditing Techniques

98. Example Calculation: Part 1 Fan Savings
Fan draw:
208V * (1 phase)^½ * 5.7A * (0.9 PF) = 1.07 kW
Hours reduced:
Was 24*365 = 8760 hrs/yr
Now 11 hrs per day * 365 days * 5/7 ≈ 2868 hrs/yr
Savings: 5892 hrs/yr
Savings = 1.07 kW * 5892 hrs = 6304 kWh
Assuming $0.15/kWh → $945.60
Energy Auditing Techniques

99. Example Calc: Part 2 Ventilation Savings
Use Sunnyvale bin weather data
Ventilation load Btu/h = (1.085)(CFM)(Toutside-Tinside)
If positive, then cooling load
If negative, then heating load
Multiply by hours in bin
Divide by equipment efficiency
Energy Auditing Techniques

100. Example bin method calc:
Energy Auditing Techniques

101. Energy Auditing Techniques
Savings Summary
Energy Auditing Techniques