How to Get the Most out of Your

Rooftop AC

Tucson, Ariz., October 12, 2016

Danny Miller

President

Transformative Wave

• RTUs serve 70% of the cooled commercial floor space in North America (~ 40B sq. ft.)

• They use 4.3 quads of energy annually (the equivalent of 34 billion gallons of gasoline)

• They consume more energy than any other type of cooling technology

Primary Reason: Low First Cost

• Low-tech (most HVAC contractors are able to install and service)

• Smaller footprint and weight reduce impact on roof construction and structural support

• They perform the basic functions effectively: heat, cool and ventilate

Why are RTUs so common?

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Excessive Energy Use Operational Issues Destruction of Capital

• Service deficiencies

• Deferred maintenance

• Low-level service techs

• Improper setpoints

• Duct leakage

• Inability to adapt to changes in the building load realities

• Over-sizing

• Constant volume fan operation

• Limited part-load operation

• Code minimum EER

• Lack advanced features available from OEMs

What Options Exist for Dealing With the Excessive Energy Use

and Operational Issues With These Systems?

• Unnecessary energy spend

• Ineffective PM programs

• Costly preventable repairs

• Short-term results from recommissioning efforts

• Premature replacement programs that cost billions

RTUs Operate at a Low Efficiency Level and Are Fraught With

Operational Issues, Which Have Significant Economic Consequences. 3

Factors

• Over-sizing

• Constant volume fan operation

• Limited part-load operation

• Code minimum EER

• Lack advanced features available from OEMs

Excessive Energy Use

DOE’s Better Buildings Advanced RTU Campaign

Replace

or

Retrofit?

5

Do RTU Retrofit Upgrades Really Save Energy?

What are Advanced RTU Retrofit Controls (ARC)?

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Core Features• Variable Speed Fan Control

• CO2-based Demand Control Ventilation

• Advanced Digital Economizer Control

Desirable Features• Remote Monitoring

• Fault Detection

• Alarm Generation

• Reporting

• Remote Diagnostics

• Smart Grid Compatibility

• Advance Cool (patent-pending)

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“Both simulation and field evaluations show that adding these control strategies to existing RTUs can reduce their energy consumption by between 30% and 60%.”

— ASHRAE Journal, March 2014

Modeled Savings Validated In the Field

Landmark study evaluated RTU

retrofit with one year of measurement

data. Average energy savings was

documented at 57%.

Consistent Validation of RTU Retrofit as an Energy Conservation Measure

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Validated by 14 different, third party field demonstrations

• 210 RTUs serving 47 buildings

• More than 20 different types of commercial buildings

• 9 ASHRAE climate zones

• 47% median energy savings

Third Party Field Trial Results Prove Significant Energy Savings

ARC Prescriptive Rebates in the U.S.

If It Didn’t Work, Would the Utility Community Support It Like This?9

Factors

• Service deficiencies

• Deferred maintenance

• Low-level service techs

• Improper setpoints

• Duct leakage

• Inability to adapt to changes in the building load realities

Operational

Issues

It’s Worse Than You Think up There!

“It’s ‘What You Don’t Know’ That’s Hurting You.”11

Supermarket Deficiency Report

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Example of Common RTU Field Findings

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Example of Common RTU Field Findings

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The Value of RTU Fault Detection Cannot be Understated!If Operators Knew, They Would Likely Do Something About It.

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Highlight:

The inability to adjust to changes in the building loads.

LED Lighting Retrofits and Unintended Consequences

What Impacts Are LED Upgrades Having on the Retail Environment? 17

How LEDs Are Making Retail Spaces More Humid

Sensible vs. Latent Load

• Retrofitting to lower lighting power densities (LPD) makes humidity control harder for RTUs. A typical retail store has an LPD of 1.0 to 1.4 watt per square foot, and the HVAC system is sized for that internal sensible load. An LED retrofit lowers the LPD to 0.4 to 0.6 watts per square foot, a 60% reduction.

• The thermostat will have less calls for cooling with lower internal loads.

• In humid climates, an LED retrofit will negatively impact the RTU’s ability to provide proper dehumidification because of compressor short-cycling.

It Can Take 10–40 Minutes of Runtime to Get Moisture out of the Unit.

Source: Shirey, D. & Henderson, H. (2004). Dehumidification at

Part Load. ASHRAE Journal. April 2004.

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A Closer Look

• Time until ‘useful latent removal’ can range from 10–40 minutes as the mixed air dew-point ranges from 50–70 °F.

• The coil acts as a ‘swamp cooler’ when the compressor cycles off.

• A reasonable rule of thumb is at a compressor run-time fraction of 0.4 (4 minutes on, 6 minutes off), no latent removal occurs.

• This is why we are finding clammy indoor environments following an LED lighting upgrade.

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Source: Shirey, D. & Henderson, H. (2004). Dehumidification at Part Load. ASHRAE Journal. April 2004.

How Can RTU Retrofit Improve Humidity Control?

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• Implementing DCV logic reduces the amount of ventilation air delivered to the space. This reduction in ventilation air can result in a drier space.

• A reduction in the fan speed during mechanical cooling mode allows the entering air to pass through the evaporator at a slower velocity. This reduces the supply air dew-point , which improves the RTU’s ability to dehumidify the space.

• Improved economizer logic often utilizes a dew-point lock out. This allows different dew-point setpoints for each facility type. Grocery applications typically want a 55-degree dew-point while office and retail typically can live with a 65-degree space dew-point.

• Some Advanced Rooftop Retrofit Controllers can recognize when compressors are short-cycling and will elongate the minimum compressor runtime to increase the opportunity for useful moisture removal.

For a full treatment of this issue, see Transformative Wave’s white paper in Energy Manager Today:“Improve Occupant Comfort & Reduce Energy Costs Through Humidity Control”

http://info.transformativewave.com/l/138811/2016-07-06/h558y/138811/19498/WHITEPAPER_Improve_Occupant_Comfort_by_Transformative_Wave.pdf21

Inherent De-Humidification Performance Advantage of 5% Lower Rh

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Case Retrofits Can Reduce Refrigeration Energy Use by 50%–80%.Source: DOE Better Buildings Alliance

Supermarket Refrigerated Case Door Retrofits Unintended Consequences

What About Those Case Credits in the Original Store HVAC Design?

• For the purposes of HVAC design, … refrigerated cases provide

the majority of the sensible cooling and some latent cooling in the

greater space of supermarket sales zones during the cooling

season.

• The loss of these case credits impacts the HVAC operation by

driving up the sensible heat ratio (SHR) demands of the space

compared to the previous open case design.

• This shift in the supermarket loads is often not recognized or

addressed by the existing HVAC systems.

Refer to: Energy-Efficient Supermarket Heating, Ventilation, and Air Conditioning in Humid Climates in the United States

J. Clark

National Renewable Energy Laboratory 23

1. Advanced RTU controls retrofit can provide the opportunity to improve the latent and sensible cooling functions of the HVAC units by adding dew point-based control for every zone.

2. Lower fan speeds in mechanical cooling and dehumidification operation increase latent cooling capabilities.

3. RTU coordination capability to leverage the capacity of surrounding units to support the increase in sensible cooling demand.

4. Ability to leverage deep-level fault detection to ensure proper ongoing operation of the HVAC systems. The increased demand on the RTUs will also increase the facility’s reliance on them. Mitigating the common dysfunction of these units will contribute to a better overall store environment with the new segregation of refrigerated cases and the body of the facility.

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How Can RTU Retrofit Assist With Impact of Lost Case Credits?

FactorsDestruction

of Capital • Unnecessary energy spend

• Ineffective PM programs

• Costly preventable repairs

• Short-term results from recommissioning efforts

• Premature replacement programs that cost billions

HVAC Equipment Repair Costs (based on Austin, Texas — 2011)

Marketing Brochure

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1. Advanced RTU controls retrofit can reduce energy use by 25%–50%.

2. Fault detection and remote diagnostics from a connected retrofit controller with advanced capabilities can identify and report problems before they escalate to more expensive breakdowns.

3. It is possible to monitor and report the frequency and duration of preventative maintenance inspections to help operators hold service providers accountable.

4. RTU coordination techniques can help to ensure more even and balanced use of the HVAC systems to avoid wearing out the few units that tend to do all of the work (80/20 rule). This helps operators avoid the pitfall of replacing all of the units when only a subset are actually at end of life.

5. Combining existing capabilities with some Emerson innovations may allow us to soon provide operators with an “odometer” of sorts on compressors to report numerous conditions and estimated time to failure.

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How Can RTU Retrofit Assist With the Destruction of Capital?

Value of Intelligent RTU Retrofit on Retailer Bottom Line

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Retailer A: 15-Year Replacement Program

Retailer B: 18-Year Replacement Program

• 1,000 locations with 10 RTUs each

• Average tonnage: 10 tons per unit

• 15-year replacement plan

• 666 RTUs replaced annually

• Cost @ $12k each

Total Capital Cost = $8,000,000

• 1,000 locations with 10 RTUs each

• Average tonnage: 10 tons per unit

• 18-year replacement plan

• 555 RTUs replaced annually

• Cost @ $12k each

Total Capital Cost = $6,600,000

Capital Preserved = $1,400,000

Company’s Stock Price to Earnings P/E = 22.5

Value = $31.5M

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A connected RTU can deliver tremendous value29

Takeaway:

RTU Retrofit Saves Energy, Addresses

Operational Issues, & Preserves Capital

Questions?

DISCLAIMER

Although all statements and information contained herein are believed to be accurate and reliable, they are presented without guarantee or warranty of any kind, expressed or

implied. Information provided herein does not relieve the user from the responsibility of carrying out its own tests and experiments, and the user assumes all risks and liability for

use of the information and results obtained. Statements or suggestions concerning the use of materials and processes are made without representation or warranty that any such

use is free of patent infringement and are not recommendations to infringe on any patents. The user should not assume that all toxicity data and safety measures are indicated

herein or that other measures may not be required.

Thank You!