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Session VII
Right-sized:
Equipment and controls for super-efficient building systems
September 7
8:30 am to 12:30 pm
4 LU/HSW/SD
After designing for maximum passive use of site resources and mitigating energy loads, the next
step to a breakthrough building is properly sized equipment and employment of advanced
controls. This session will explore the concept and application of designing and specifying
equipment and controls for buildings that are already designed to take care of themselves, and
need mechanical intervention only during periods of peak demand. Systems such as hybrid
natural-mechanical ventilation systems and other approaches to engineer the mechanical system
to be as small (efficient) and effective as possible will be explored.
Chris Schaffner PE, LEED
Nick Gayeski PhD
These materials are provided to registered participants in the AIA+2030 Professional
Series and may not be reproduced without the written consent of the provider.
RIGHT SIZED: EQUIPMENT AND CONTROLS FOR SUPEREFFIICENT BUILDING SYSTEMS™
Logistics and Expectations
- Be on time
8:30-8:45
Prior sessions recap and Session 7 intro
8:45-10:30
Case studies/Q&A
10:30-10:45
Break
10:45-11:00
Exercise
11:00-12:30
Case studies/Q&A
- Be open, honest and candid
- Safe learning environment
- Smartphone/Blackberry etiquette
-Get to know your new BSA Space- feel at home here!
Architecture 2030
Quick overviews-Three related 2030 advocates:
- Non-profit organization founded by Ed Mazria in 2002.
- Authors of “The 2030 Challenge”
- Major Goal: To achieve a dramatic reduction in greenhouse gas
(GHG) emissions of the Building Sector by changing the way
buildings and developments are planned, designed and
The 2030
Challenge
AIA 2030
Commitment
AIA+2030
Professional Series
constructed.
Architecture 2030
AIA 2030 Commitment
American Institute of Architects requirements
The 2030 Challenge
How:
Two months
Six months
One year
Annually
- Design strategies
- Technologies/systems
- Off-site renewables
Source: www.architecture2030.org
Establish a
team or leader
to guide the
firm’s plan
Implement min.
of four actions
items related to
firm operations
Develop sustainability
action plan that
demonstrates success
toward 2030 goals
60% of what?
Report progress
toward goals
and share
publicly
Source: www.aia.org
AIA 2030 Commitment
Reporting summary
FIRM NAME ALL OFFICES
Design Work 2009
Overall Course Goals
“The AIA+2030 Professional Series helps design professionals
create buildings that meet the ambitious energy efficiency goals
of the Architecture 2030 Challenge. Ten 4-hour sessions offer
strategies to reach 60% reduction in fossil fuel greenhouse gas
emissions, giving design professionals the knowledge and leverage
to create next-generation, super efficient buildings-and providing
firms with the skills that will set them apart in the marketplace.”
LAND USE WATER ENERGY MATERIALS HEALTH AIR QUAILITY
Boston Series (Today)
3/16/12
4/13/12
GETTING TO 60: THE POWER OF TARGETS + LOAD REDUCTIONS™
5/11/12
ACCENTUATE THE POSITIVE: CLIMATE RESPONSIVE DESIGN™
6/8/12
SKINS: THE IMPORTANCE OF THE THERMAL ENVELOPE™
7/13/12
PASSIVELY AGGRESSIVE: EMPLOYING PASSIVE SYSTEMS FOR LOAD REDUCTION™
8/10/12
ILLUMINATING SAVINGS: DAYLIGHTING AND INTEGRATED LIGHTING STRATEGIES™
9/7/12
RIGHT-SIZED: EQUIPMENT AND CONTROLS FOR SUPER-EFFICIENT BUILDING SYSTEMS™
10/12/12 SITE POWER: RENEWABLE ENERGY OPPORTUNITIES™
11/9/12
What is the best solution to this problem?
SETTING + ACHIEVING ENERGY GOALS WITH INTEGRATED DESIGN™
THE HAND-OFF + STAYING IN SHAPE: OPERATIONS, MAINTENANCE + EDUCATION™
12/14/12 PUTTING IT ALL TOGETHER: ACHIEVING 2030 GOALS ON THE PROJECT AND AT THE OFFICE™
A. Reduce the load
B. Consider oxen
C. Get a bigger donkey
lighting
LEARNING OBJECTIVES
heat loss
people
solar gain
fans &
pumps
plugs
- Describe and apply right-sizing as it pertains to
passive energy conservation strategies
- Utilize controls to optimizing the efficiency of
equipment
Before you buy a bigger donkey…..
- Incorporate energy efficient strategies to
maintain occupant comfort
REDUCE LOAD FIRST !!
Chris Schaffner, PE, LEED Fellow
Principal & Founder
The Green Engineer, LLP
chris@greenengineer.com
Simple
Is better than Complex
Manual
Less
Is better than Automatic
Is better than More
Green means…
Passive
Is better than Active
Energy Efficiency Opportunities
•
•
•
•
•
•
•
•
Building Siting And Orientation
Building Massing
Building Envelope
Plug/Process Loads
Lighting
HVAC System
Domestic Hot Water
Elevators
•  Safe and Healthy
•  Resource Efficient
•  Flexible and Adaptable
•  Durable and Maintainable
Strategy For Success
1) Reduce Demand
2) Harvest Site Energy
3) Maximize Efficiency
4) Building Commissioning
5) Ongoing Operations &
Maintenance
Right Sizing?
Potential Benefits of Right
Sizing
What is Right Sizing?
•  Match capacity to actual loads.
•  Match systems to actual operation.
•  Design for the typical day, not the
extreme day (for the 90%, not the
10%)
Tunneling Through the Cost
Barrier (RMI)
Lower capital costs
Reduced energy consumption
Longer equipment life
Improved comfort and indoor
environmental quality
•  smaller, more efficient systems…
•  …Which lead to less space taken up by
those systems…
•  …Which leads to lower capital costs.
•
•
•
•
Tunneling Through the Cost
Barrier (RMI)
Oversizing has a multiplier
effect
•
•
•
•
If I overestimate loads by 25%
Then plan for future expansion 25%
Then add a 25% safety factor
I’ve just oversized my systems by
95%
Risks
•  Unknown/unanticipated conditions
(loads, patterns of use)
•  Unmet design criteria
•  Value Engineering & Cost Estimating
•  Liability
•  Future growth
•  Fees?
Example
How many
Fume Hoods
do we need?
How did too
many Fume
Hoods lead to
the need for
structural
upgrades?
Daylighting Example
Engineer assumed
daylight dimming
would be VE’d –
never included it in
calculations
Result - Savings
never realized
Common Misconceptions
Missing Information
•  “We need to increase system
capacity to plan for global warming.”
•  “Increasingly high tech office
systems are driving up internal
loads.”
•  If the engineer doesn’t know, we
guess high.
•  Lighting Design vs. Equipment Sizing
•  Lack of information needed to
properly size systems and fear of
liability.
“Nobody ever got
fired for
oversizing a
system”
Consequences of Oversized
Systems
•  Higher capital costs
•  Reduced efficiencies and
controllability of systems
•  “cycling”
•  Start up energy losses
•  Equipment may not meet rated
performance
Key Engineering Design
Factors
•
•
•
•
•
•
Climatic Conditions
Architectural Design
Design Criteria
Internal Loads
Diversity
Safety Factors
Rules of Thumb
•  Not based on
actual loads.
•  Not based on
actual operation.
•  Already have
safety factors
built into them.
•  Often lead to
oversized
systems.
Climatic Conditions
•  Outdoor Design Criteria –typically
defined by codes and standards,
client and standard practice.
•  ASHRAE Design Criteria based on
outdoor design conditions 0.4%/99.6% (Most Conservative)
1%/99%
2%/98% (Least Conservative)
Climate Data For
Boston
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Architectural Design
Form
Orientation
Shading
Envelope materials
Infiltration Rates
Complex gets
simplified
•
•
•
•
•
•
Design Criteria
•  Comfort Requirements – ASHRAE 55
•  “Design for flexibility and growth”
•  Critical environments - Less tolerant
Indoor Environmental Quality
(IEQ)
•  HVAC plays a primary role in IEQ,
but not an exclusive one.
•  Air quality – pollutant source control
•  ASHRAE 62 – Ventilation
•  ASHRAE 55 – Thermal Comfort
Comfort
•
ASHRAE Standard 55 provides guidance on thermal comfort
Factors
•  Air temperature
•  Effect of air movement, or lack of, and velocity.
•  Radiant effect
Adaptive comfort – range of comfort expands when occupants have
control.
•  Mechanical cooling can be eliminated even in warm climates.
•  Increasing air movement can expand comfort range.
Humans and comfort range
•  Level of activity and style of dress.
•  Individual controls.
•  Dress code policies
ASHRAE 55 Comfort Zone
Internal Loads
Diversity
•  If inaccurate or incomplete load data
leads engineers and energy modelers
to make best guess assumptions, use
of “rules of thumb” and added safety
factors.
•  Where possible, measure
•  Consider diversity
Diversity – Ratio of actual load relative to the peak load,
accounts for:
•  Scheduling - When people are not in the building.
•  Partial use of equipment, space, etc.
•  Non-simultaneous loads or use (e.g. not all equipment
running at full power at the same time)
•  Other factors for non-coincidental loads such as usage
profiles
•  Typically ranges from 20-90%!
•  Engaging the building owner in the diversity
assumption discussion and providing both first cost
and life cycle cost implications.
Real vs. Assumed Equipment
Loads
Dynamic Load Assessment •  Dynamic variations impact system capacity.
•  Typical cooling assumptions: peak solar gain (sunny day),
peak internal gains (constant with no diversity), average
daily temperature profile/cycle.
•  Typical heating assumptions: no solar gain or internal loads
benefit, constant temperature.
•  Dynamic load assessment: real (varying) climate data, real
(varying) loads, and realistic operational profiles.
•  Internal loads: occupant density and associated heat gain
(both sensible and latent); occupancy patterns
(scheduling); equipment power density (W/sf) and usage
patterns; lighting power density (W/sf), controls and usage
patterns.
•  Validation and measurement of available data to identify
real loads.
•  Dynamic load synergy – daylighting
Case Study – Harvard
Blackstone
•  LEED
Platinum
•  Office
Renovation
•  Uses
demand
control
ventilation
Blackstone - Results
•  Downsize AHU 15%, resulting in first
cost savings
•  Earned 7 of 10 possible points under
EAc1, and also earned IEQc1
•  Achieved LEED Platinum
•  Actual performance within 1% of
predicted performance.
Reasoning for safety factors
in load analysis
cool down
•  Building warm-up and
•  Future growth/spare capacity
•  Risk associated with manual system
components that rely on occupant
participation, such as internal window
shades.
•  Risk due to limited or incomplete
internal load information provided by
owner and/or design team.
•  Code considerations
Issues in commonly used load
analysis programs
•  Program defaults may assume loads
occur 24 hours a day.
•  Heating or cooling loads not
influenced by the value of thermal
mass.
•  Dynamic load profiles or system
scheduling are often over-looked.
•  Most load programs assume airmixing systems with cooling capacity.
System Selection Guidelines
and Considerations
•  High system performance at part load.
•  Adaptability to varying operational
(dynamic) loads.
•  Long-term plan to handle load growth or
reduction.
•  Ease of retrofit appropriate for building
type/use, for example:
•  Simplicity of operation – Avoid designing
systems that are not compatible with the
available time and expertise of the staff
responsible to operate and maintain them.
Key mechanical engineering
factors
•  Fan power is reduced by a factor of 3
when system airflow is reduced.
•  Water is 16 times more efficient at
moving energy (btus) than air.
•  Primary goals for air systems are to
reduce system pressure and friction
losses, and limit airflow turbulence.
Both require effort from the fan to
overcome, which in turn creates an
energy demand.
•
•
•
•
•
Plant Equipment
Recommendations
Modular systems
Space for future system expansion
Multi-stage operation
Turndown capability.
Variable speed equipment.
Mechanical Engineering?
1) Take previous successful set of drawings.
2) Change the box that indicates the name of
the project.
3) Submit drawings to client.
4) Building is constructed.
5) Client gripes about discomfort.
6) Wait for client to stop griping.
7) Repeat process.
Engineer Eng Lock Lee – “Natural Capitalism”
Passive System Evaluation
•  Are passive and active systems doing
double duty – can one be eliminated?
•  What are the dynamic loads with passive
systems in place?
•  Can active equipment be down-sized due to
passive system contribution?
•  How much of the load does the passive
system carry? Can the active backup
system be inexpensive and simple if only
needed on occasion?
•  Passive systems do not break or wear out
over time – Passive Survivability
When does oversizing help?
Distribution Systems – Yes
•  Big pipes = smaller pumps
•  Marginal cost of a slightly large pipe/
duct/wire is small
Plant Equipment – No
•  Oversized equipment is expensive
and runs inefficiently (usually!)
HVAC System Alternatives
•  Compare various HVAC systems
Condensing Boilers
•  Very High Efficiency
•  Use selection matrix scoring system
in decision making.
DISPLACEMENT
VENTILATION
Supply air is introduced at the
floor level at a temperature only
slightly below the desired room
temperature. The cooler supply
air "displaces" the warmer room
air, creating a zone of fresh cool
air at the occupied level. Heat and
contaminants produced by
activities in the space rise to the
ceiling level where they are
exhausted from the space
TM570
Environmental Systems I: HVAC
DEDICATED OUTDOOR AIR
SYSTEMS (DOAS)
HYDRONIC SYSTEMS CAN BE COMBINED WITH A
VENTILATION ONLY, AIR SYSTEM, TO PROVIDE WHAT IS
CALLED A DEDICATED OUTDOOR AIR SYSTEM OR DOAS.
DOAS SYSTEMS INSURE THAT ADEQUATE VENTILATION IS
PROVIDED REGARDLESS OF HEATING OR COOLING
REQUIREMENTS. DUCTS ARE SIZED JUST LARGE ENOUGH
FOR VENTILATION – TYPICALLY 1/5 THE SIZE THAT
WOULD BE REQUIRED FOR FULL CONDITIONING IN AN
AIR BASED SYSTEM.
THIS SYSTEM TYPE HAS ADVANTAGES IN TERMS OF INDOOR
AIR QUALITY AND ENERGY EFFICIENCY.
IN THE RECENT PAST MOST BUILDINGS HAVE BEEN
DESIGNED WITH VAV SYSTEMS, BUT THERE IS
CONSIDERABLE INTEREST IN DOAS IN THE BUILDING
COMMUNITY.
TM570
Environmental Systems I: HVAC
UNDERFLOOR
DISPLACEMENT
THE DISPLACEMENT
CONCEPT IS COMBINED
WITH A RAISED ACCESS
FLOOR. IN ADDITION TO
THE BENEFITS FROM THE
DISPLACEMENT CONCEPT,
IT ALSO PROVIDES
ADDED FLEXIBILITY, IN
THAT SPACES CAN BE
EASILY RECONFIGURED.
TM570
Raised Floor being installed
Environmental Systems I: HVAC
DOAS
•  Fan Coils
•  Chilled Beams
•  Radiant
Variable Refrigerant Volume
Heat Pumps
•  Distribute refrigerant instead of water.
•  Multiple heat pumps on single condensing
unit
•  Inherent heat recovery
HVAC Controls
•  On/off
•  Demand response controls
•  Metering/monitoring
Architect’s Role in Right Sizing
•
•
•
•
•
•
Early dialogue with engineering team
Set energy targets
Set specific system level targets
Require energy analysis
Owner communication and education
Empower the engineering team to
right size their systems
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Predicted Peak Energy Loads
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Design Phase
Predictions
Predicted Peak Energy Loads
•  By Engineer
•  Equipment sizing
•  By MIT
•  Utility planning
Predicted Annual Energy Consumption
(kBTU/sf/yr)
•
•
•
•
By energy model
Evaluate design alternatives
Determine utility incentives
Document LEED Credits
Predicted Annual Energy Consumption
(kBTU/sf/yr)
Energy Modeling as a Design Tool
Early modeling
Evaluate design alternatives
•  Building envelope
•  Shading
•  HVAC System Selection
Mid-design modeling
Refine strategies
Final Documentation Model
For LEED
Balance Point Temperature Calculation
MIT Data Collection Strategy
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Metering Issues
Multiple trades involved
–  Electrical
–  Data
–  Pipe fitters
–  Controls
Demand – Chilled Water Results to
Date
Chilled Water
•  Design demand: 3,350 tons
Most engineers do not understand
Diagrams needed for inclusion in drawing set
•  MIT prediction:
2,484 tons
•  Actual demand:
2,354 tons
Ranges on meters
–  Engineers’ numbers not reliable
–  Over sizing: loses low end accuracy
Demand – Steam Results to Date
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Demand - Predicted Electrical Load
Details
Electrical Design:
•  Lighting:
335 kVA
(1.04 W/sf)
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•  Receptacle:
2,344 kVA
•  Mechanical: 2,326 kVA
(6.6 W/sf)
(6.6 W/sf)
Demand - Results to Date
Demand Estimation
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Why do we overestimate the load?
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•  Engineers are conservative !!!!
–  Multiple safety factors
–  Process loads are overestimated
–  Rules of Thumb outdated
–  Lack of feedback
Usage Results to Date
Causes of Disparity
Predicted vs. Actual (Site) Energy
Use:
Why models differ from reality:
Labs21 Average: 393 kbtu/sf/yr
Predicted:
365 kbtu/sf/yr
Actual:
323 kbtu/sf/yr
•  12% less than predicted
•  19% less than Labs21 average
•  Same issue with assumptions as peak loads
•  More assumptions in play –schedules, part loads
•  Assumes systems operate perfectly
•  Some modeling elements forced by 90.1
•  Weather
•  38% less than ASHRAE
90.1-2004
KGS: Who We Are & What We Do
Right Sizing HVAC Equipment:
Controls, Operations and Performance
Nick Gayeski, PhD
Partner and Co-Founder
Engineers, scientists and software developers
Clockworks: Web-based software & analytics library
for automated fault detection and diagnosis, ongoing
commissioning, measurement and verification
Engineering services to support our customers
Copyright © 2012
Copyright © 2012
Topics
KGS: Bearing witness to right and wrong sizing
Trending equipment performance data 24/7/52
Right sizing conventional wisdom
Automated analytics detect when systems are not
performing properly
Right sizing controls
How does right/wrong sizing impact
operational performance?
Direct and assist owners, O&M, and service
providers to take action to correct problems,
including the outcomes of wrong sizing
How do I avoid this mess and deliver high
performance buildings?
Copyright © 2012
Copyright © 2012
Right sizing conventional wisdom – a review
Right-sizing controls
Reduces capital costs
Operational strategies and controls can be made to
use the right systems, at the right times, just enough
• Smaller boilers, chillers, pumps, pipes, coils, ducts, etc
• Less space for equipment?
Reduces operational costs
Systems designed with flexibility to adapt to real
conditions rather than over-sized to handle extremes
• More efficient operation = less energy use + lower energy costs
•
•
•
•
Reduces maintenance costs
• Less cycling/appropriate use = longer life, less wear
Variable speed drives
Equipment that is efficient at part-loads
Proper zoning and scheduling
Controls that adjust to real thermal loads and drivers
Happier occupants, happier clients
• More comfortable conditions, better indoor env. quality
• Higher performance buildings
Copyright © 2012
Copyright © 2012
Right-sizing controls
On/off and turning it down in practice
•
Time-of-day scheduling
•
•
If you don’t need it, turn it off
If you don’t need it so much, turn it down
•
•
Copyright © 2012
Instructions to junior staff from a senior operator turned researcher
at a national laboratory on how to operate buildings efficiently
On/off of equipment or availability
Static pressure
•
Night setbacks/setups
•
Reset schedules
•
•
•
•
•
Variable speed drives to allow modulation to loads
•
•
•
Posted on the door outside the operations center for a 50+ building
national facility with >$1 billion business volume
Copyright © 2012
Static pressure reset based on damper positions
Differential pressure reset based on coil valve positions
Discharge air temperature reset
Outdoor air temperature reset schedules
Pumps
Fans
Chillers/compressors*
It’s simple, but details still matter
Take chiller efficiency, for example
•
Some chillers operate efficiently at full-load
•
Some chillers operate efficiently at part-load
•
Especially in retrofit projects
•
•
•
•
Find out how reducing thermal loads changes the
operating conditions of the HVAC equipment
Can the system modulate to accommodate
changes in the thermal loads?
How does that effect its efficiency?
Consider additional HVAC retrofits? E.g. VSDs
Architects need to
•
•
•
Copyright © 2012
Ask engineers to explain how design decisions
effect system performance and sizing, but also
PROVIDE INFORMATION to help engineers
answer those questions
Enable performance management
•
Ensure the building automation system includes
adequate data to measure performance
•
Provide for long term monitoring and trending of
performance data
•
Leverage new technologies to provide
Optimal and model-predictive controls
Emerging technologies for model-predictive control and
optimization may
•
• Reduce peak loads
• Reduce demand charges
• Reduce overall energy costs
For example
•
• Building IQ
• Clean Urban Energy
• Optimum Energy
Does it work? Can we model and design with it?
•
• To be determined
Copyright © 2012
e.g. Automated diagnostics identify wrong-sizing
performance impacts and corrective actions
• Automated ongoing commissioning
• Fault detection and diagnosis
• Ongoing performance measurement and verification
•
Information enables adaptation to wrong-sizing et al
• As-built performance always differs from expected
• Use, operations, and performance changes with time
Copyright © 2012
Copyright © 2012
Case study: Over-sized rooftop units
Summary
•
•
•
•
•
Small retail store
5 rooftop units
Diagnostics for commissioning
Compressor cycling on 1 RTU
RTU capacity over-sized
Case study: Over-sized VAV systems
•
Higher static pressures lead to more fan energy
•
Low VAV box damper positions imply that zones require lower
airflows to meet cooling than design
•
Reducing static pressure causes fan to slow down and consume
less energy, deliver less flow, and allow dampers to open
Consequences
•
Shorter compressor life
Solution
•
•
•
•
Copyright © 2012
Programmable thermostats
Time of year schedules
Only use RTU in extreme summer
Right-size/replace RTU
Copyright © 2012
Case study: Over-sized VAV systems
Summary
•
•
•
•
•
Large research laboratory
100,000 CFM AHUs
Serving 50-100 VAV boxes
Low average damper positions
High static pressure setpoint
Case study: Oversized boiler/heating system
Summary
•
•
Multi-family residential building
Boilers short cycling
Consequences
•
•
More maintenance required
Shorter boiler life
Consequences
•
Wasted fan energy
Solutions
•
Solutions
•
•
Dynamic static pressure reset
Reduce static pressure setpoint
Copyright © 2012
•
Chillers are generally more efficient delivering higher chilled
water temperatures
Case study: Oversized cooling system
Summary
•
•
•
•
•
Keep boilers off more of the year
Reduce heating hot water supply
temperature
Right-size the boilers
Copyright © 2012
Case study: Oversized cooling systems
•
•
Small temperature differences on a chilled water loop means the
loop thermal load is small relative to the capacity
Supply temperature raised to improve chiller efficiency
or flow reduced to reduce fan power and save energy costs
•
Large commercial building
CHW Loop exhibited low
temperature differences
Nighttime operation unnecessary
except for small data center
Consequences
•
•
Excess chiller operation
Additional energy costs
Solutions
•
•
Copyright © 2012
Copyright © 2012
How and why does wrong sizing happen?
How do I avoid this mess and deliver high
performance buildings?
Risk and liability
Establish customer expectations and goals early
• Design for extreme conditions (0.4% design day)
• Safety factors on safety factors
• Customer expectations on comfort and adaptability
Coordinate design process effectively and ensure
accurate information is provided for sizing
Bad assumptions and lack of information
•
•
•
•
Copyright © 2012
Proper zoning of systems
Dedicated sensible cooling for data
center
Understand the importance of
Occupancy levels, schedules and patterns
Lighting power density and patterns
Plug load power density and patterns
Limitations of modeling tools/modelers
• matching loads to capacities efficiently,
• operation and efficiency of systems at part-loads, and
• controls that modulate systems to efficiently meet loads
Construction 101
Utilize new technologies to
• Design vs as-built
• Design vs as-operated
• assure performance goals are met,
• address as-built system problems and inefficiencies, and
• deliver energy efficiency and peak load reduction
Copyright © 2012
Thanks! Questions!
Nick Gayeski, PhD
Partner and Co-Founder
Image Credits:
Pacific Northwest National Laboratory, ReTuning Resources
BuildingIQ
KGS Buildings, LLC
Copyright © 2012