How to Get the Most out of Your Rooftop AC

Transcription

1 How to Get the Most out of Your Rooftop AC E360 Annual Conference Atlanta, Ga. April 11 Danny Miller President Transformative Wave

2 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. Why are RTUs so common? Low-tech (most HVAC contractors are able to install and service) Smaller footprint; weight reduces impact on roof construction and structural support They perform the basic functions effectively: heat, cool and ventilate. Primary reason: low first cost 2

3 RTUs Operate at a Low Efficiency Level and Are Fraught With Operational Issues Which Have Significant Economic Consequences Excessive Energy Use Operational Issues Lack of Part-Load Control Over-sizing Constant volume fan operation Limited part-load operation Code minimum EER Lack advanced features available from OEMs Service deficiencies Deferred maintenance Low-level service techs Improper setpoints Economizer failures Inability to adapt to changes in the building load realities Typically two stages of capacity Typically single-speed fan operation High demand peaks Major swings in sensible and latent cooling impact Compressor short-cycling What options exist for dealing with the excessive energy use and operational issues with these systems? 3

4 Excessive Energy Use Factors Over-sizing Constant volume fan operation Limited part-load operation Code minimum EER Lack advanced features available from OEMs 4

5 Energy Management Technology Adoption Path Often-Overlooked??? Efficiency Opportunities Related to HVAC 5

6 Savings From EMS and Data Analytics 100% Energy Usage Energy Savings Impact Applying a building automation system for HVAC control will typically provide a 10 15% reduction in HVAC energy usage based on operational savings. Big Data analytics will typically provide additional efficiency gains of 3 8% on adjusted energy baseline. 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Baseline Setpoint & Schedule Data Analytics 6

7 Patented Variable-speed drive Advanced economizer control CO 2 -based demand control ventilation Multiple new sensors and data points Validated by: Reduces overall HVAC energy use 25 50% 7

8 Advanced Rooftop Retrofit Controls Core Features Variable-speed fan control CO 2 -based demand control ventilation Advanced digital economizer control Desirable Features Remote monitoring Fault detection Alarm generation Reporting Remote diagnostics Smart grid compatibility Advance Cool (patented) Does an RTU retrofit really save energy? 8

9 Modeled Savings Validated in the Field Landmark study evaluated our RTU retrofit solution with one year of measurement data. Average energy savings was documented at 57%. 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

10 ARC Prescriptive Rebates in the U.S. If it didn t work, would the utility community support it like this? 10

11 Additional Savings From Rooftop AC Retrofit Energy Savings Comparison 100% 90% 80% Energy Usage The CATALYST produces additional HVAC energy savings of 25 50% beyond the operational savings from BAS. The CATALYST savings are HARD measurable and repeatable savings. 70% 60% 50% 40% 30% 20% 10% 0% Baseline Setpoint & Schedule Data Analytics CATALYST 11

12 Operational Issues Factors Service deficiencies Deferred maintenance Low-level service techs Improper setpoints Economizer failures Inability to adapt to changes in the building load realities 12

13 It s Worse Than You Think up There! It s what you don t know that s hurting you. 13

14 Supermarket Deficiency Report 14

15 CA Title 24 Compliant Economizer Fault Detection 15

16 CA Title 24 Compliant Economizer Fault Detection (cont d.) 16

17 The Value of RTU Fault Detection Cannot Be Understated! If Operators Knew, They Would Do Something About It. 17

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19 Additional Savings From Fault Detection and Diagnostics Energy Savings Comparison Additional energy savings from operators knowing when economizers have failed or other common system problems will vary greatly but reported to save as much as 30% of compressor energy use. 100% 90% 80% 70% 60% 50% 40% 30% 20% Energy Usage 10% 0% Baseline Setpoint & Schedule Data Analytics CATALYST FDD 19

20 Lack of Part-Load Control Factors Typically two stages of capacity Typically single-speed fan operation High demand peaks Major swings in sensible and latent cooling impact Compressor short-cycling 20

21 Another Missing Piece Part-load control of compressors with variable-speed fan Compressor modulation combined with fan speed control allows for precise balance of efficiency and capacity. Climate-specific control strategies Improved dehumidification outcomes in humid markets Sensible cooling optimization for dry climates 21

22 Inherent Dehumidification Performance Advantage 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 22

23 Available as a field replacement for fixed-capacity compressors Field retrofit via CATALYST and VFD for Copeland Scrolls 23

24 Additional Savings From Part-Load Compressor Control Energy Savings Impact Part-load control of first-stage compressor can provide additional energy savings. Emerson has modeled savings that suggest another 8% reduction in overall HVAC energy use. 100% 90% 80% 70% 60% 50% 40% 30% 20% Energy Usage 10% 0% Baseline Setpoint & Schedule Data Analytics CATALYST FDD Compressor Control 24

25 Value of Intelligent RTU Retrofit on Retailer Bottom Line Retailer A: 15-Year Replacement Program 1,000 locations with 10 RTUs each Average tonnage, 10 tons per unit 15-year replacement plan 666 RTUs replaced annually $12k each Total Capital Cost = $8,000,000 Retailer B: 18-Year Replacement Program 1,000 locations with 10 RTUs each Average tonnage 10 tons per unit 18-year replacement plan 555 RTUs replaced annually $12k each Total Capital Cost = $6,600,000 Capital Preserved = $1,400,000 Company s Stock Price to Earnings P/E is 22.5 Value = $31.5M 25

26 RTU retrofit is energy savings and a whole lot more! 26

27 Thank You! 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. 27