What cost-effective options are available for building owners interested in reducing their building’s energy use? CEE's Director of Engineering Services, Mark Hancock, P.E., will discuss rooftop unit retrofits as a scalable energy-saving approach and recommend next steps.

1. OPTIMIZING EXISTING ROOFTOP UNIT EFFICIENCY
A Study Focused on Cold Climate Conditions
Mark Hancock, P.E. |
Center for Energy & Environment
Webinar: November 12, 2014

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Current Field Research Projects
In Progress
•Improved Effectiveness of Commercial ERVs
•Condensing Boiler Optimization
•Optimized Operation of Pool Facilities
•Reducing Commercial Building Duct Leakage
•Multi-Family Building Envelope Aerosol Sealing
•Effective Ventilation in Multi-Family Buildings
•Secondhand Smoke Exposure in Vehicles
•DOE Building America | Retrofit Water Heating
•DOE Building America | Combi-System Measure Guidelines
•DOE Building America | Combustion Safety Guidelines
•DOE Building America | Demonstration House
2013-14 Archived Webinars & Upcoming Publications
•Window Retrofit Technologies
•Large Building Air Leakage
•Tankless Water Heaters*
•Heat Pump Water Heaters in MN
•Optimization of Existing RTUs
•Combi Systems

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Today’s Presenter
•With CEE since 1987
•Specializes in existing building commissioning and HVAC field diagnostics
•Former program director for the Public Buildings Enhanced Energy Efficiency Program (2009 – 2014)
Mark Hancock, P.E. Director of Engineering Services

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This project was supported by a grant from the Minnesota Department of Commerce through the Conservation Applied Research and Development (CARD) program.

12. OPTIMIZING EXISTING ROOFTOP UNIT EFFICIENCY
A Study Focused on Cold Climate Conditions
Mark Hancock, P.E. |
Center for Energy & Environment
Webinar: November 12, 2014

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So Why Roof Top Units (RTUs)?

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RTU Market
•46% of all commercial space conditioned by RTU’s
•2.7 billion ft2 of commercial retail floor space (CBECS 2003)
•Wide variety of applications
•Office
•Commercial
•Manufacturing
•Industrial
•Warehouse
•Retail
•Medical

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RTU’s are widely used
Source: Google maps
5 RTU’s
6 RTU’s

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RTU’s are widely used
Source: Google maps
20 RTU’s

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RTU’s are widely used
Source: Google maps
50 RTU’s

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Why RTU’s
•Packaged units
•Integration of heating and cooling in a single unit
•Reliability
•Low initial cost
•Wide range of sizes to meet requirements of the space
•Plug and Play
•Network of trained installers and service technicians

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The evolution of a Cell phone

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The evolution of RTU

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What’s the problem with RTU?
•Generally RTUs operate inefficiently
•Standard efficiency
•Constant speed
•No options for advanced controls
•Lack of maintenance
•Compacted design results in challenges for control
•Stand alone control
•Settings conflict with neighboring RTU
•Schedules (if used) don’t match space requirements
•Often over sized
•Pick and place from manufacture

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Goals of our study
•Evaluate advanced RTU control strategies
•For efficiency
•For cost effectiveness
•For large scale delivery for CIP offering
•Confirm savings found by other projects
•Small projects in very different climates
•What are the savings in Minnesota?
•Collect performance data
•Target 60 RTUs
•Collect data that spans MN winter and summer conditions

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The Optimization Packages
•Premium Ventilation
•Digi-RTU Optimizer
•Catalyst Optimizer

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Targeted Optimization Packages

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Premium Ventilation
Source: RTU Premium Ventilation Proof of Concept Field Test
2
Roof Line

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Premium Ventilation
Source: KMC FlexStat Product Literature

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Targeted Optimization Packages

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Digi-RTU Optimizer

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Standard Operation

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Variable speed control

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Targeted Optimization Packages

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Catalyst Optimizer Installation

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Manufactures Claims
•Premium Ventilation
•18% to 44% of HVAC use (vary regionally)
•Source “Unitary HVAC Premium Ventilation Upgrade” Reid Hart 2011
•Digi-RTU
•40% to 60% reduction in energy
•30% to 60% decline in demand
•Source Bes-Tech / Digi-RTU website
•Catalyst
•25% to 50% reduction in Energy use
•Source Transformative Wave / Catalyst website

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Previous Studies
66 RTUs
66 RTUs

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Climate Zones

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Our Test sites

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How we collected data
•Internet connected data loggers
•For data collection
•For control
•Flip/Flop Test protocol
•Allowed for collection of two years of data in one year
•Accounted for changes in the building
•Occupied times
•Production
•Staffing
Standard
Optimized
S
S
O
S
S
O
S
S
S
S
O
O
O
O
O
Year one
Year two

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Data Collection Period

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Our Test sites

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Distribution of RTU’s: Cooling
Number of RTU’s

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Analysis
•Primary Objectives
•Estimate electric and gas use with and without optimizers
•Estimate savings from optimizers
•Compare savings between optimizer technologies
•Estimate savings for each site
•Calculate simple payback
•Based in measured data and installed costs
•Develop energy savings calculator
•Secondary Objectives
•Analyze IAQ and indoor comfort with and without optimizers

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Savings: Electric

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Savings: Electric

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Savings: Gas

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Savings: Gas

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Savings: By Site
Digi, Prem Vent
Prem Vent
Catalyst
Digi-RTU
Prem Vent
Digi-RTU
Optimization

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Savings: By Site

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Savings: By Site
Digi-RTU
Digi-RTU
Prem. Vent
Catalyst
Prem. Vent
Optimization

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Optimizer Economics

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Optimizer Economics

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Cost Effectiveness

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Paybacks by Capacity
Field Measured Data

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Savings: By groups

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Savings: By groups

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Space Temperature Control

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Space Temperature Control

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IAQ Control

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Key Findings
•All technologies achieved significant electric savings
•Gas savings were negative or statistically insignificant
•Savings were highly variable
•Fan settings and minimum OA dampers settings were not consistent
•Advanced controls did not achieve cost-effective energy savings
•Larger units with more operation would improve cost effectiveness

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Key Findings
•Control Units were affected by Optimizers
•Best optimizer for a space depends on situation
•“One size does not fit all”
•Market is rapidly expanding
•New innovation
•Product maturity
•Contractor support critical to success of products
•Products tested had issues with MN Climate (Zone 6)

61. Mark Hancock | 612.335.5861 mhancock@mncee.org

62. Question & Answer
Webinar Archive Link:
http://www.mncee.org/Innovation-Exchange/Resource-Center/

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