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As the value of exisng properes are enhanced with greater energy eciency, in recent years manufacturers have increasingly embraced demands for more energy ecient lis. However, as the requirements will be dierent for commercial, industrial and residenal real estate, a high degree of technical insight is required to implement the right blend of energy eciency measures to opmise these benefits.


to reveal the opportunities for energy saving and cost reduction. There are a wide range of country-specific standards relating to lift energy efficiency. In the UK, the BREEAM scheme offers possible credits in relation to lifts, within Section Ene 06 “Energy efficient transportation systems”. International standard - ISO 25745 – Energy performance of lifts, escalators and moving walks – includes methods of measuring actual energy consumption of lifts and for carrying out periodic energy verification checks in operation. Part 2 of the standard covers energy calculations and classification for lifts and provides a method to estimate energy consumption on a daily and an annual basis.


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In terms of practical applications, outlined below are just some that can help to reduce lift energy consumption and the carbon footprint of a building.


Standby mode


Powering down equipment when it is not in use of course delivers substantial energy reductions, particularly in buildings where there are periods of inactivity. For example, the power side of the lift controller and other operating equipment, such as lift car lighting, user displays and ventilation fans, can be automatically switched off when the lift has been idle for a prescribed length of time. Any required standby mode energy could be supplied with the installation of one or two solar panels, depending on the levels of sunlight available.


ABOUT THE AUTHOR Dean Taylor is Regional Director for Vertical Transportation at TÜV SÜD Dunbar Boardman, Europe’s leading lift, escalator and access consultancy, developing and delivering solutions across all sectors of the built environment since 1981. Operating throughout the UK and Ireland, as well as the Middle East and India, it is part of TÜV SÜD, one of the world’s leading technical service providers.


Variable Voltage Variable Frequency (VVVF) drives


VVVF drive systems are the key to efficient lifts. Older drive systems use separate motors and generators, which results in energy being lost due to the number of elements employed by the system. However, VVVF drives use a single control system, therefore reducing ‘lost’ energy. Energy Savings can be as high as 30 per cent in comparison to older direct current (DC) drive equipment.


Regenerative drives


Lifts fitted with regenerative features convert the energy generated from the motor into electricity that can be reused elsewhere in the building. Compared to older lifts, regenerative lifts are 20-30 per cent more energy efficient. When regenerative drives are used in conjunction with VVVF drive systems, energy consumption savings of between 40-50 per cent can be made.


It is vital to correctly assess energy demand 34 BUILDING SERVICES & ENVIRONMENTAL ENGINEER FEBRUARY 2021 Read the latest at: www.bsee.co.uk


hen considering lifts within a building, it is vital to correctly assess their


energy demand


ENERGY MANAGEMENT How green is your lift?


Li manufacturers are developing innovave, ecient equipment Energy efficient lighting


A simple way to contribute to increasing the energy efficiency of a lift is to replace old lighting with LEDs. This will help to bring running costs down, particularly relating to energy use and the reduction of maintenance cycles, as older incandescent or fluorescent lighting uses 90 per cent more power. Additional energy-saving options include smart lighting that switches off when the lift is not occupied and dimmable controls so that passengers can adjust light levels.


Solar power


Solar-powered systems can deliver an energy saving of up to 50 per cent. The number of required photovoltaic panels to successfully power a lift of course depends on the level of sunlight that is available, consequently this technology is usually better suited to sunnier regions.


Destination control


Smarter use of lifts, where less power is required as they are not being needlessly used and car capacity can be optimised, will increase


energy efficiency – good news for the environment and the financial bottom-line. Destination control is where you enter your desired floor in a central control panel before being directed to a specific lift - rather than jumping into the first one that arrives. This optimises traffic, making it potentially possible to reduce the number of lifts and/or derive a better service in a building. Destination control has been proven to achieve system energy savings of up to 25-30 per cent.


Traffic analysis


Traffic analysis assesses the demand and movement patterns of a building and determines the optimum number and size of lifts based on the anticipated passenger demand. In the past, traffic analysis involved a simple mathematical probability formula, which gave a ‘system interval’ for the lifts. This was based on a handling capacity, which related to a percentage of the population of the building in a five-minute period at peak-time. Modern computer software now enables complex traffic to be simulated in any given building type. Modelling this type of scenario over a full day most accurately reflects the peak passenger traffic for a


given building and its use. The resulting analysis gives an output with an ‘average waiting time’ and an ‘average time to destination’, which is more representative of the normal user experience. The software can also be used to calculate energy use over a given period, which is useful to ensure that the most efficient equipment can be specified.


The total energy consumption of the lift installation is also dependent on how effective the planning stage is. For example, if stairs are accessible, attractive and adjacent to the lifts, there is likely to be a reduction in passenger use for short trips. It is also advisable to avoid over-sizing, as larger lifts result in greater inertia, larger motors and therefore increased energy use. However, in order not to compromise the service for passengers, the focus should always be on appropriately sized lifts rather than ‘the smaller the better’. It is also important to factor in the type of traffic that will be using the lifts. For example, in a shopping centre there is likely to be family groups using prams and shopping trollies. This means that lifts must be larger in order to carry enough people per journey. Also, in a residential development, they will be required to accommodate large items such as furniture and ambulance stretchers.


Embrace innovation


Several key factors are driving demand for energy efficient and reduced emissions buildings, which are increasingly seen as a business opportunity. This includes market pressure, tenant expectations, operating cost reduction, social/corporate responsibilities and legislative requirements.


Consequently, lift manufacturers are developing innovative, efficient equipment that secures them a competitive edge and this should be embraced by the building services industry.


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