Peter Herzog's energy management book summary 1213

Hello,
I teach state-of-the-art existing buildings operations and maintenance
(EBOM) and energy management courses for some of the foremost training
institutions in New York City. A substantial part of the energy management
teaching is based on Peter Herzog’s book: “Energy-Efficient Operation of
Commercial Buildings” which is also a course handout.
Written some years ago, in my opinion this is still the very best
practical guide on the implementation of energy management in commercial
(and multifamily) buildings, and is very well received by my students.
Mr. Herzog has authorized the publication and free use of this
presentation for non-profit, educational purposes, as long as the content is not
altered in any way.
Mr. Herzog’s book can be found here:
http://www.nweei.org/commercial-efficiency-text-in-print.html
Moreno Tagliapietra, 914-712-0823, mor.dor@att.net – January 2014

Herzog:
“Energy-Efficient Operation
of Commercial Buildings”

A summary by Moreno Tagliapietra – December 2013

Scope and Purpose
This presentation is a summary of the principles, tools
and techniques expounded by Peter Herzog in his book
“Energy-Efficient Operation of Commercial Buildings”
It is intended to be used as a review of the book’s key
points after its content has been exhaustively studied

Herzog: “Energy-Efficient Operation of Commercial Buildings” – Summary by Moreno Tagliapietra – Dec 2013

Herzog’s Building Energy Efficiency Model

Major loads
Identified
Prioritization
of ongoing
activities


Energy Use Allocation Methods

1. Top-down allocation:
 Beginning from the aggregated energy consumption shown in the
utility bills, systems demand and operating hours are estimated and
used to disperse the total use among the different systems
(consuming the same type of energy)
 This method has poor precision but is accurate enough to identify a
building’s major loads and prioritize energy conservation measures
 It also provides for final verification of the accuracy of the
equipment/system level allocation methods: the disaggregated figures
must sum up to the totals shown in the utility bills


2. Bottom-up, take-off method:
• This method works at the equipment/system level
• Manufacturer’s specs and name plate data are used to
estimate equipment/system demand
• Hours of operation are estimated as in the previous
method
• Precision and accuracy are better than with the top-down
method because variables such as input/output full-load
rates and efficiency are known but others are still
estimated including partial/variable load factors and
firing rates, and schedule


2. Bottom-up, measurement method:
 Instrumentation is used, most often in conjunction with
data loggers, to test/measure the actual energy use of
individual pieces of equipment or whole systems
 Tests and measurements are conducted for a period of
time representative of all possible working conditions
 This method affords the highest level of confidence in
terms of precision and accuracy of energy use allocation


Achieving Energy Efficiency Through O&M
 3 Tenets:
• Efficient purchasing
• Efficient operation
• Efficient equipment
 Benefits:
• Substantial energy and cost savings
• Low implementation costs
• Higher comfort and productivity
• Better info for capital improvement decisions



 Barriers:
• Potential savings not understood by management
• Maintenance procedures not designed for operating efficiency
• Focus on engineering rather than on management processes
• Management structure inhibits operating efficiency
• No available methods for managing operating efficiency



 The process, overview:
•
•
•
•
•
•

Identify the types of energy consumed by the building
Identify the equipment consuming the energy
Estimate the energy consumption of the equipment (from the bills)
Determine the true energy demand
Measure the true consumption
Optimize O&M to minimize the difference between the two



 The Role of Management:
• Value energy-efficient operation
• Develop enthusiastic participation
• Recognize cross-functional nature of effort
• Define return on investment
• Institute methods of accounting
• Designate a start-up leader
• Recognize needs during start-up phase




•
•
•
•
•

Start-up activities:
Create an energy management file
List energy consuming devices and systems
Collect drawings and specifications
Tour building to trace energy flow paths
Draw schematic diagrams


Figure 3-12
Electrical
Riser
Diagram


Figure 3-123
Schematic of
Air Handling
Unit


Estimating Electricity Use

Constant electricity users:
•Lighting
•Constant rate electric motors
•Variable rate electric motors
•Two-speed motors
•Office equipment
•Electric water heaters
•Miscellaneous equipment

Weather-variable electricity users:
•Electric heating
•Electric cooling
•Electric heat pumps



 Estimating electricity use:
•
•
•
•

Assemble utility bills information
Gather information on operating schedules
Estimate annual use of electric equipment
Allocate total annual electrical energy cost


, Figure 4.3
Electrical use for example office building


, Figure 4.5
Graphing electric bills data


, Figure 4.7 - Operating schedule


, Figure 4.10
Allocation of annual electrical energy cost


 Estimating natural gas use: the process is the same as per
electricity
 Page 69, Figure 5-4 – Combined natural gas & oil


Page 70, Figure 5-5 – Natural gas AVG daily use x month


, Figure 6-1
Ongoing activities
M&V,
new baseline


 From set-up to on-going activities:
• The most useful outcome of the set-up activities is to identify the
building’s major loads so that the on-going activities can be
prioritized
• At this stage, it is key for the energy management team to secure
the participation and cooperation of everyone who influences how
and when systems are operated
• The final goal here is to ensure that equipment is running only
when necessary and that only the required amount of energy is
consumed


 Step 4: Measure actual energy use
• Decide what to measure
 Energy consumption, rate over time
 Fixed vs variable rates
• Decide how to measure and with what instruments

Utility meters, aggregate consumption

Individual equipment measurements
o Temperature
o Humidity
o Pressure
o Flow
o Electrical current
• Data loggers


 Step 5: Determine required energy use
• The energy management team finds out what the actual, often
variable building loads are and, consequently, what the actual
systems set points and hours of operation should be
• It is common to discover that many building systems either
operate when there is no need or that their schedule is out of
synch with the current space occupancy schedule


Page 89, Figure 6-8 – Required vs. real use graph



 Step 6: Minimize the difference between actual and
required energy use
• Estimate savings potential
• Explore all the EEM(s) that would achieve these savings and
select the ones with the highest ROI
• Implement the EEM(s), measure and verify the results
(M&V program)


 Example # 1: Lighting, office building
• Draw an electrical riser diagram
• Measure light intensity with a light meter
• Measure actual lighting use with clamp amp-meters at the distribution
panel feeders, connected to a data logger
• Determine the required lighting schedule
• Adjust lamp wattage for the light level recommended by IESNA
• Adjust actual to required lighting use with the adoption of automatic
controls (occupancy and vacancy sensors, timers, multi-level switches,
digital controllers, daylight harvesting, zoning (common areas vs. task),
dimming/trimming)
• Upgrade light fixtures and lamps
• Take into consideration the code LPD requirements

Page 112, Figure 7-12 – Actual vs. required energy use profile



Basic lighting calculations (annual, fluorescent, take off method):
Demand, kW = (Watts/lamp x # lamps/fixture x # fixtures x 1.1 ballast) /
1000
Schedule, Hours = op hours/day x days/week x weeks/year
Use, kWh = demand kW x schedule hours
Cost = use kWh x $/kWh
Note: Lighting is a fixed load unless operator’s dimming is used


Lighting power measurements (pg 154):


 Example # 2: roof top Air Handling Units,
ventilation + cooling, office building:
• Identify energy consuming devices (compressor + fans)
• Draw a diagram of the AHU system with distribution
• Identify the unit sequence of operations:

Programmed daily schedule with room thermostat over-run
 Supply air temp = 55dF, VAV boxes
 Perimeter radiators, room thermostat driving VAV boxes as well
(prevents simultaneous heating + cooling)
 Economizer

Supply fan with modulating inlet vanes, pressure sensor in
supply air

DX cooling system with sensor in supply air (55dF)

ventilation + cooling, office building
 Goals:
• The fans operating schedule must match as closely as possible
the needs of the building occupants
• The mixed air economizer control must function as intended
• The supply air temperature must be maintained at the highest
acceptable value
• Unnecessary simultaneous heating and cooling must be avoided
at the perimeter spaces



 What to measure (key operating variables):
• Fan on/off schedule
• Mixed air temperature in economizer mode
• Supply air temperature
• Possibility of simultaneous heating and cooling of perimeter
spaces


 Where to measure:


AHU

Page128


Example # 2: roof top Air Handling Units,
Page 128 - Figure 8-13 – AHU measurements findings


Example # 2: roof top Air Handling Units,
Energy management team conclusions:






The AHU required operating hours are found to be 65/week
The AHU actual operating hours are 122/week or + 57 hours/week
The AHU operates 52 weeks/year (ventilation!)
Reducing the operating hours of the 3 phase fan would save:
(30A x 460V x 1.73 x 57h/week x 52weeks/year x 0.18$/kWh) / 1000
= = $ 12,737/year

 The compressor savings are difficult to calculate and are estimated
to be about 20% of the original cooling costs based on known
operating conditions


Motors, page 157:


Motors, pg 157:


Motors
Page 161,
Figure A-2:


Electric water heating, Pg 168:


Electric heating & cooling, Pg 168:


Miscellaneous electrical uses, Pg 169:

“Usually there [is] a number of electricity-consuming
devices that are too small to be itemized in this general
allocation, but their aggregated energy use may account for
5% to 15% of the total annual consumption.
Examples include pneumatic control air compressors, small
circulating pumps and exterior building lighting.
Account for miscellaneous electrical users by assuming
they consume 10% of the annual total kWh.”


Estimating constant fuel consumers, Pg 183:


The end, any
questions?


Peter Herzog's energy management book summary 1213

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