Optimizing Existing Rooftop Unit Energy Efficiency

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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In Progress



















• Combi Systems

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In Progress



















• Combi Systems

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In Progress



















• Combi Systems

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In Progress



















• Combi Systems

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In Progress
















• Tankless Water Heaters*



• 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.

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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Source: Google maps

20 RTU’s

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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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Digi-RTU Optimizer

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Standard Operation

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Variable speed control

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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 N

um

ber

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)

Mark Hancock | 612.335.5861

[email protected]

Question & Answer

Webinar Archive Link:

http://www.mncee.org/Innovation-Exchange/Resource-Center/

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Optimizing Existing Rooftop Unit Energy Efficiency

Documents

commercial space condition

energy environmentwebinar

energy efficiency program

development card program

public buildings

rtu market46

todays presenterwith

units rtus