ENPM808W
Energy Efficiency/Energy Audit and Conservation
Week III, Lecture 1: Energy Audit
Procedures and Energy
Benchmarking
Dr. Michael Ohadi
Spring 2015
Energy Auditing
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Energy audit is part of the overall energy program
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Audit: official examination and verification of accounts and
records
Energy audit tasks per ASHRAE:
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Collect and analyze historical energy use
Study the building and its operational characteristics
Identify potential modifications that will reduce the energy
use and cost
Perform an engineering analysis of the modifications
Prepare a rank-ordered list of modifications
Prepare a report to document the analysis process and the
results
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ASHRAE Commercial Building
Energy Audit Levels
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Three Levels
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ASHRAE Level 1: Walk-Through Analysis
ASHRAE Level 2: Energy Survey and Analysis
ASHRAE Level 3: Detailed Analysis of Capital
Intensive Modifications
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ASHRAE Level 1 Analysis
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Walk-through analysis
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Analyze energy bills
Conduct a brief on-site visit
Brief survey of the building characteristics and
occupants
Recommendations on low-cost/no-cost
improvements
Preliminary Identification of Capital Improvements
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ASHRAE Level 2 Analysis
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Energy survey and engineering analysis
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Analyze energy bills in more detail
More detailed building survey
Breakdown of energy use within the building
Review operational and maintenance procedures
Provide savings and cost analysis of all practical
improvements
Provide a list of potential capital-intensive
improvements
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ASHRAE Level 3 Analysis
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Detailed analysis of capital-intensive
modifications
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Very detailed building survey
Detailed review of operational and maintenance
procedures
Detailed building modeling/simulation (Transys,
EnergyPlus) with validation from data gathering
Focus on analyzing potential capital-intensive
modifications
Provide detailed project cost and savings calculations
with a high level of confidence
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Obtain actual contractor pricing if possible
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Energy Audit Procedures
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Pre site visit
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Site visit
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Information gathering
Building Survey
Post site visit
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Calculate energy savings and generate report
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Pre Site Visit
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Obtain review Mechanical, Electrical, Lighting
and Plumbing Drawings
Obtain Floor plans
Obtain basic facility physical information
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Building area (SQFT), year built, types of utilities
Weather information
Perform a Utility Analysis
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Calculate EUI (Energy Utility Index) for
Benchmarking
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Site Visit
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Survey mechanical, electrical and lighting systems
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Envelope
Lighting
HVAC
Domestic Hot Water
Laundry
Food Preparation
Conveying Systems and Other
Identify Energy Conservation Measures
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Gather related information such as equipment name plate
information, motor efficiencies, lighting measurements
etc.
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Post Site Visit
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Energy Savings and Payback Calculations
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Energy Conservation Measures
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List assumptions
Provide basic methodology of the calculations
– May be asked to provide more details
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Results
Report findings including cost and payback
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Provide reasonable cost estimates
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Payback calculations
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Typically expected to be within ±20% for ASHRAE Level 2
Simple payback = Cost / Savings
Complex (based on time value of money, inflation, depreciation,
before and after tax considerations)
Recommendations
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Energy Benchmarking
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Utility Analysis
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Collect and review minimum 1 year of utility data
Electric, gas, steam, propane, oil, chilled water, etc.
 Graph consumption and cost data
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– Energy load profile, Demand, Load Factor
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Look for seasonal patterns and anomalies
Energy Benchmarking:
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Important part of ASHRAE Audit Procedure
Calculate Energy Utilization Index (EUI): kBtu/ft²
Cost Index: $/ft²
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Energy Utilization Index (EUI): kBtu/ft²
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EUI = Total Energy Consumption of the building divided
by the total building area
Site EUI
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The Btu value of energy is measured at the point it enters
the building
Source EUI (Primary Energy Consumption Index)
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The Btu value is equal to site energy plus losses that occur
in the generation, transmission, and distribution of energy
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Incorporates inefficiencies at the power plants, transmission and
distribution lines etc.
Source EUI Varies regionally due to the diversity of fuel
sources utilized in the power plants. Average values used
under consensus.
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Site Energy Utilization Index (EUI):
kBtu/ft²
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Total Energy Consumption of the building
divided by the total building area
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Example: An Office Complex in Landover, MD
 345,065
ft²
 Annual Electricity Consumption: 5,145,874 kWh
– x3.413 kBtu/kWh = 17,562,868 kBtu
 Annual
Natural Gas Consumption: 158,100 Therms
– x100 kBtu/ Therm = 15,810,000 kBtu
 EUI
= 96.7 kBtu / ft²
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Forms of Energy Utilization Index (EUI)
Energy/Productivity
Indicator
Advantages
Btu/ft2
-Concise. Most commonly used.
-Accurate when process energy is low or constant
and weather is consistent.
-Very consistent (easy to measure sq feet).
-No measure of production.
-Doesn’t account for weather
-Assumes energy is linear with floor space.
-Concise.
-Accurate when process energy dominates.
-Appropriate for comparing plants with similar
production profiles.
-Difficult to measure “units of production”.
-Doesn’t capture high HVAC and/or lighting
contributions.
-Concise.
-Accurate when HVAC system energy dominates.
-Consistent between similar structures/plants
(easy to measure or obtain degree day data).
-Disregards production energy and process
needs.
-Buildings with large thermal mass don’t respond
as quickly to degree days.
Btu/unit-degree day-ft2
or
Btu/unit-degree day
-Captures several variables.
-Somewhat consistent and more accurate than
the above measures.
-Can capture a very specific need.
-More complicated.
-More difficult to comprehend.
Btu/sales dollar or
Cost of energy/$ sales
or $ profit
-Easy to compute.
-Relates energy consumption to profitability.
-Demonstrates $ results, not just conservation.
-Does not account for inflation.
-Difficult to account for all variables that influence
profitability.
-Similar to a measure of production.
-Easy to get accurate data.
-Good when process energy is the dominant
energy.
-Consistent across plants and possibly industries.
-Energy is often not linearly proportional to labor
costs.
-Does not account for high HVAC/lighting
demands.
Btu/unit of production
Btu/degree day
Btu/direct labor
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Disadvantages
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How to compare EUI between
different buildings?
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U.S. D.O.E. Energy Information Administration
provides statistical data
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http://www.eia.doe.gov
Databases for Energy Intensity
 Residential
 Commercial
Buildings
 Manufacturing Industries
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Experience!
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U.S. Commercial Buildings Energy Intensity
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Energy Star Portfolio Manager
for energy benchmarking
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Free benchmarking tool by EPA and DOE
Interactive energy management tool that allows
tracking and assessing energy and water consumption
Manage Energy and Water Consumption for all
Buildings
Rate Building Energy Performance
Estimate Carbon Footprint
Set Investment Priorities
Verify and Track Progress of Improvement Projects
Gain EPA Recognition
Improve property value => High profile tenants
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Energy Star Portfolio Manager
How does it work?
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https://www.energystar.gov/istar/pmpam/index.cfm
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Create online account
Add new facility
Define space use types
Add energy consumption data
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Obtain energy star score and interpret results
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Enter energy bills directly
Energy Star 50 = Average Building
Energy Star 75 = Energy Star Certified Building
Requires to be a Licensed Professional Engineer (PE) to certify
Track monthly changes with the score
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