Connecting, Nurturing, Creating for Sustainable Environment

Energy Efficient Retrofits Guide: Lifts
   

2.4.17 Variable Voltage Variable Frequency (“VVVF”) Lift Drives

Why?

§  significant energy savings
§  enhanced equipment lifetime

Where do they work best?

Office Buildings (Types 1, 2 & 3)

Hotel Buildings

(also residential buildings or any other high-rise buildings)

Image Source: ebm-papst

Overview

VVVF lift drives are able to regulate both voltage and frequency inputs to the motor throughout the journey via a frequency inverter. This allows VVVF lifts to use much less electric current and energy during acceleration and deceleration, and reduces the wear and tear of the equipment during the start or stop phase of the motor[1].

These lifts can be used in various types of multi-storey buildings for energy and cost savings.

Modelled Costs and Saving Potentials (assumptions are listed in Appendix A)

VVVF Lift Drives

Scenario Type

End-of-Life

Total Cost

Capital Cost (per m2 building area)

HK$0

HK$375

Payback Period (years)

0

92

Saving Potentials (per m2 building area)

Cost

HK$4/year

Energy

4 kWh/year

Carbon

2 kg CO2-e/year

Advantages

  • technology is mature
  • moderate to significant energy savings depending on building height
  • extended equipment lifetime
  • improved safety, speed, reliability and riding comfort
  • they are becoming a norm for new lift installations

Limitations

  • high retrofitting costs which make this very expensive unless a new lift system is needed – this is why the figures above are based on the incremental cost of VVVF lifts compared with a like for like replacement at end of life

Additional Considerations

  • amount of energy saved depends on the load of the lift
  • can be combined with regenerative braking drives (see Section 2.4.18 below) for maximum energy efficiency

Relevance to Landlords and Tenants

  • cost savings primarily for landlords, with potential savings for tenants in the longer run


2.4.18 Regenerative Braking Lifts

Why?

§  able to harness energy that would otherwise be dissipated as heat
§  energy savings in air conditioning

Where do they work best?

Office Buildings (Types 1, 2 & 3)

Hotel Buildings

(also residential buildings or any other high-rise buildings)

Image Source: Mitsubishi Electric

Overview

In conventional lifts, the power generated by traction is dissipated as heat in the building, whereas lifts with a regenerative function are able to use their motors as a generator when the carriage is travelling down, and feed the current back into the facility’s electrical grid for usage in elsewhere. When the lift car is travelling up with a light load, or down with a heavy load, the system can generate more power than it uses. Over time, the power generated can add up to noticeable savings.

The amount of regenerative power produced depends on several factors, including building height, operating speed, elevator capacity and type/age of the lift.

Modelled Costs and Saving Potentials (assumptions are listed in Appendix A)

Regenerative Braking Lifts

Scenario Type

End-of-Life

Total Cost

Capital Cost (per m2 building area)

HK$13

HK$390

Payback Period (years)

3.1

95

Saving Potentials (per m2 building area)

Cost

HK$4/year

Energy

4 kWh/year

Carbon

2 kg CO2-e/year

 

Advantages

  • technology is mature
  • improved safety, speed, reliability and riding comfort
  • energy savings in both lift and air-conditioning use, by being able to generate electricity and reduce heat dissipation at the same time
  • surplus energy can be used by other electrical systems[2]

Limitations

  • high retrofitting costs which make this very expensive unless a new lift system is needed, which is why the figures above are based on the incremental cost of regenerative braking lifts compared with a like for like replacement at end of life
  • actual energy savings are dependent on lift usage and building height

Additional Considerations

  • they work best and save more energy in high-rise buildings with multiple lifts
  • there are also some add-on regenerative braking modules available in the market

Relevance to Landlords and Tenants

  • cost savings primarily for landlords, with potential savings for tenants in the longer run

 

 

⇐ Back To Table of Contents

    Follow BEC on

       

    Sign Up For BEC Updates:
     
Return To Top