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checkInstall variable frequency drives on pumps and motors.

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Description

Install variable frequency drives (VFDs) , also called variable speed drives, or VSDs, on HVAC system fans, pumps and other motors to enable speed to vary in response to system demand.

  • Project Talking Points

    • The horsepower required to run a fan or pump varies with the cube of its motor speed, resulting in large energy and cost savings when the motor speed is allowed to modulate in response to demand. In a 1995 report on variable air volume systems, the U.S. Environmental Protection Agency estimated that installing VFDs can result in 52 percent average annual energy savings.
    • The life of building system equipment can be extended by gradually ramping up pumps and motors when increased capacity is required and by reducing the percentage of time pumps and motors work at full capacity. 
  • Triple Bottom Line Benefits

    • Cost benefits: Energy savings and increased equipment life reduce costs significantly.  See case studies for specific examples. 
    • Environmental benefits: Reducing energy consumption decreases carbon emissions and environmental impact. (see Benefits Calculator page).
    • Social benefits: Installing VFDs can allow for improvements in thermal comfort which can enhance patient and staff experience.

    Quality and Outcomes:  Metrics are in development.  If you have suggestions, please  contact us or participate in the discussion below.

  • Purchasing Considerations

    If you have suggestions for purchasing considerations, or suggested sample contract language for any product or contracted service, please participate in the discussion below.

  • How-To

    1. Determine who's on the team. This can include the building engineer, MEP engineer, HVAC maintenance personnel, and building automation system (BAS) manager.
    2. Consult with any users who will be affected by the installation and/or will need to understand and approve procedures to override the system. This may include the manager or director of the area affected by the change, the infection prevention staff, the safety officer, and or the chief operating officer.
    3. Review energy usage data generated by the facility’s BAS or similar to calculate the variability of the facility’s load profile and establish baseline energy use. VFDs generate the highest efficiency benefits in variable load conditions.
    4. Catalog which fan and pump motors could have VFDs installed. Consider the following equipment, as suggested in ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings:
      • Supply and return fans
      • Booster fans
      • Fan coil units
      • Exhaust fans
      • Cooling tower fans
      • Liquid coolers
      • Condenser fans
      • Secondary chilled water pumps
      • Domestic and hot water pumps
    5. Analyze which fan and pump motors are appropriate for retrofitting a VFD.  Analysis should consider the ability of the system design to perform properly under variable flow. For example, where fan systems require minimum flow rates and room to room pressure differentials, these must be maintained. In general, VFDs function best when installed on high efficiency equipment.
    6. Either remove inlet guide vanes (or other flow modulating device) or remove the actuator and open the guide vanes to avoid counteracting the VFD’s modulation of airflow.
    7. Use a harmonics calculator to identify whether harmonic filters should be installed.
    8. Install and program VFDs to avoid operating equipment in the critical speed range. Consult the pump/motor manufacturer for information about optimal speed, vibration, and resonance.
    9. Establish new control sequences to optimize energy reduction while maintaining proper system performance. For example, sequence control of the VFDs to either run the maximum or minimum number of motors consistent with loads and energy savings. Alternately, upgrade controls to modulate fan capacity according to the position of zone dampers.
    10. Incorporate VFDs in the facility’s commissioning program (see performance improvement measure Retrocommission HVAC controls) and preventive maintenance program (see performance improvement measure Practice preventive maintenance of major HVAC equipment).
    11. Assure that areas with specific minimum code-required air exchanges are not adversely affected by implementation of the VFD program. 
  • Tools

  • Case Studies

    Cheyenne One Medical Office Building, Advanced Energy Design Guide for Small Hospitals and Healthcare Facilities (requires free registration to download)

    • Key Points
      • Installed VFDs on air handlers and large supply fans. Combined with exterior-zone only VAV space heating and carbon dioxide monitoring.
      • All green strategies combined resulted in 50-55% energy savings over a comparable medical office building. 4.5 year projected payback period.

    Saint Francis Care

    • Key Points
      • Installed VFDs on fans and on cold water, hot water, and chilled water pumping systems.
      • Received ENERGY STAR label.
  • Regulations, Codes and Standards, Policies

    American Society for Heating, Refrigerating and Air-Conditioning Engineers (www.ashrae.org)

    Air-Conditioning, Heating, and Refrigeration Institute (www.ahrinet.org)

    U.S. Department of Energy, Energy Efficiency & Renewable Energy

    Disclaimer: The references above are intended to provide guidance on compliance considerations related to implementing this PIM; however, they may not address every possible consideration. We welcome your comments and additions – please contribute to the conversation using the comment box below.

  • Cross References: LEED

    • LEED for Existing Buildings: Operations + Maintenance
      • Energy & Atmosphere Prerequisite 1: Energy Efficiency Best Management Practices—Planning, Documentation, & Opportunity Assessment
        • Document the current sequence of operations, develop a building operating plan, develop a systems narrative, create a preventive maintenance plan, and conduct an energy audit that meets the requirements of the ASHRAE Level I - Walk-through assessment.
      • Energy & Atmosphere Prerequisite 2: Minimum Energy Performance
        • Establish the minimum level of operating energy efficiency performance by achieving an energy performance rating of at least 69 using the EPA’s ENERGY STAR® Portfolio Manager tool; or, demonstrate energy efficiency at least 19% better than average following the LEED Reference Guide for Green Building Operations & Maintenance; or use the alternative method described in the LEED Reference Guide for Green Building Operations & Maintenance AND have energy meters that measure energy use.
      • Energy & Atmosphere Credit 1: Optimize Energy Efficiency Performance
        • Achieve increasing levels of operating energy performance relative to typical buildings of similar type utilizing any of the methods described in Energy & Atmosphere Prerequisite 2.
      • Energy & Atmosphere Credit 3.1: Performance Measurement—Building Automation System
        • Utilize a computer-based building automation system (BAS) that monitors and controls major building systems.
      • Energy & Atmosphere Credit 5: Measurement & Verification
        • Develop a Measurement and Verification plan by incorporating the Calibrated Simulation method; or the Energy Conservation Measure Isolation as specified in the International Performance Measurement & Verification Protocol Volume III.
    • LEED for Healthcare: New Construction and Major Renovations
      • Energy & Atmosphere Prerequisite 1: Fundamental Commissioning of Building Energy Systems
        • Designate a commissioning authority to commission the heating, ventilating, air condition systems and associated controls.
      • Energy & Atmosphere Prerequisite 2: Minimum Energy Efficiency Performance
        • Establish the minimum level of energy efficiency for the proposed building and systems by a whole building energy simulation; or a prescriptive compliance path utilizing the ASHRAE Advanced Energy Design Guide (AEDG) for Small Hospitals and Healthcare Facilities; or a prescriptive compliance path complying with ASHRAE Standard 90.1.
      • Energy & Atmosphere Credit 1: Optimize Energy Efficiency Performance
        • Achieve increasing levels of energy performance beyond the prerequisite standard to reduce energy usage.
      • Energy & Atmosphere Credit 5: Measurement and Verification
        • Develop a Measurement and Verification plan by incorporating the Calibrated Simulation method; or the Energy Conservation Measure Isolation as specified in the International Performance Measurement & Verification Protocol Volume III.
  • Cross References: GGHC

    •  Green Guide for Health Care Operations Section
      • Facilities Management Prerequisite 1: Energy Efficiency Best Management Practices—Planning, Documentation, & Opportunity Assessment
      • Facilities Management Prerequisite 2: Minimum Energy Efficiency Performance
      • Facilities Management Credit 1: Optimize Energy Efficiency Performance
      • Facilities Management Credit 4.3: Building Operations & Maintenance: Building Systems Monitoring 
  • PIM Synergies

  • Education Resources

    Energy UniversityEnergy University Courses

    The American Society for Healthcare Engineering (ASHE) has approved the courses below for continuing education credits. ASHE issues credits in quarter-hour increments, and a total of 10 contact hours equals 1 continuing education credit.

    Active Energy Efficiency Using Speed Control

    Many motors only have two settings: on and off. They operate at constant speed. If a motor turning at constant speed is driving a device or process that requires less output, adjustments are required to achieve the desired output level. This adjustment is often achieved by letting the motor run at full speed, while using downstream devices to block part of the output. This is like driving your car by having one foot fully depressing the accelerator pedal, and the other on the brake to constantly control the speed. It sounds absurd, but this is still one of the most common control methods. An estimated 60% of motors are not speed controlled. The focus of this course is to explore the different ways we can control motor speed efficiently and with minimal physical stress on equipment. In addition, we'll discuss other advantages such as controlled starting and regulated torque.

    ASHE has approved this course for .50 contact hour.

    Efficient Motor Control With Power Drives Systems

    In buildings, nearly three quarters of the electricity consumed is used to turn motors. For a typical motor, the lifetime energy bill is equivalent to 100 times the cost of the motor itself. The money invested in motors, is merely 1% of their total cost. And installing and maintaining those motors accounts for only 2% of overall motor costs. 97% of costs associated with motors are spent on the energy required to operate them. This course will provide an overview of power drive systems and motors along with insight on efficiency. This course will also cover, gears - types, efficiency and maintenance.

    ASHE has approved this course for .50 contact hour.

  • More Resources

  • PIM Descriptors

    Energy

    Level: Intermediate

    Category List:

    • Building and Maintenance
    • Controls
    • HVAC

    PIM Attributes:

    • Basic Device Upgrades
    • System Upgrades

    Improvement Type:

    • Retrofit/Renovations
    • New Buildings
    • Operations and Maintenance

    Department:

    • Engineering/Facilities Management
  • Interested in underwriting this PIM? Contact us to find out how!

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