Lift energy use, ISO 25745 and the route to lower running costs

Where the energy actually goes

On a modern traction lift, energy use splits roughly 40% running and 60% standby — though the ratio inverts on heavily-used installations. The running component covers the motor, drive, lighting and ventilation while the car is moving. The standby component is everything else: controller, position indicators, car lighting, machine-room ventilation, alarm circuits and (on older installations) constantly-energised motor-generator sets.

This is why on a typical office lift used 200 cycles a day, the single highest-impact upgrade is rarely the motor — it is putting the controller, lighting and door operator into a managed sleep mode between calls.

ISO 25745 in plain English

ISO 25745-1:2012 defines how to measure lift energy consumption. ISO 25745-2:2015 defines how to calculate annual energy consumption and assign an energy class from A (best) to G (worst) — the same scale building managers are familiar with from EPCs and appliance labelling. ISO 25745-3:2015 does the same for escalators and moving walks.

The classification is calculated from a measured running-energy figure (in Wh per cycle, per kg of useful load) plus a measured standby figure, weighted by a usage profile based on the building type and traffic intensity. The standard publishes default usage profiles for residential, office, hotel, hospital and other common building types — so a like-for-like comparison between lift offers is possible without bespoke modelling.

Where the realistic savings come from

On an existing lift, the modernisation interventions that move the energy class one or two bands are well-established:

• VVVF (variable voltage variable frequency) drive replacing a two-speed AC or DC drive — 40–60% reduction in running energy, with regenerative variants returning braking energy to the grid.
• Gearless permanent-magnet motor replacing a worm-geared AC motor — efficiency from typically 60–70% up to 90%+.
• LED car lighting and demand-driven car ventilation — running 24/7 on older installations, the saving is annualised, not per-cycle.
• Controller sleep mode — putting the controller, indicators and lighting into a managed low-power state during quiet periods. Often the single largest standby reduction.
• Modern door operator with brushless DC motor and adaptive force — both faster (reducing per-cycle motor time) and lower-energy.
• Regenerative drive paired with the existing motor where the motor is healthy. On a mid-rise office lift, a typical payback is 4–7 years on energy alone.

What the numbers actually look like

A 630 kg, 1.0 m/s, 5-stop traction lift in an office, used to ISO 25745 "intensity 3" (medium traffic, ~750 cycles/day), with an older worm-geared two-speed motor and an always-on controller, will typically use 4,500–6,500 kWh/year. The same lift modernised to a gearless VVVF regenerative drive with sleep-mode controller and LED lighting will typically use 1,400–2,200 kWh/year — a 65–70% reduction.

At a UK commercial electricity rate of £0.28/kWh (2025 indicative), that is £900–£1,200/year per lift in direct energy saving, before any carbon-reporting or BREEAM-credit benefit. On a building with six lifts, the annualised saving funds a meaningful slice of a wider modernisation programme.

How to ask for energy-class performance in a tender

The cleanest contractual specification is to require the offered lift (or modernised lift) to achieve a stated ISO 25745-2 energy class — typically Class A for new build, Class B as a minimum for modernisation — at a stated usage intensity. The supplier is then obliged to evidence the class with measured or calculated data referenced to the standard, not marketing-page claims.

For modernisations, requiring a before-and-after energy measurement (over a 7-day reference period using a calibrated logger on the supply) gives an objective basis for snagging — and a credible figure for ESG reporting.

Practical checklist for duty-holders

• Ask your maintenance contractor for the current ISO 25745-2 energy class of each lift, calculated against your building's actual usage intensity.
• On any modernisation, specify a minimum energy class as a contract requirement.
• Specify a regenerative VVVF drive as standard for any lift with three or more floors of travel and medium-or-higher traffic.
• Include controller sleep-mode, LED car lighting and demand-driven ventilation as baseline scope, not optional extras.
• On new builds, request the modelled annual energy consumption (kWh/year) in the tender response — not just the energy class, which can compress big differences.
• Where the building has an EPC, BREEAM, LEED or ESG-reporting commitment, ensure your lift specification feeds those reports — the data is straightforward once it is specified to ISO 25745.