A study for improving the energy efficiency of lifts with adjustable counterweighting

This article presents a study of the potential energy efficiency improvement by means of adjusting the lift counterweight. The lift energy consumption in different counterweight set-ups is studied by employing measured lift traffic and energy consumption data from an office building in Finland. Overall, dimensioning the counterweight based on traffic analysis is one of the fastest and most cost-effective means of improving the energy efficiency of lifts. The results from the building imply, however, that with a relatively constant loading throughout the day, the continuous adjusting of the counterweight provides limited energy savings compared to systems where the counterweight is sized according to the average load. Nevertheless, active adjustment of the counterweight size may provide considerable savings in lift systems if there is a wide variation in the car loading between the hours of the day. Furthermore, reducing the counterweight potentially improves the ISO 25745-2 energy efficiency classification of the lift, thus increasing the product attractiveness in the market. Practical application: This article presents practical approaches to analysing the energy consumption of counterbalanced lifts. The modelled results can be used to optimise the mass of the counterweight in order to achieve considerable energy savings in the actual or expected traffic profile.