The world’s population has increased six-fold in the past 150 years, while at the same time becoming increasingly urbanised each year.
The need for more people to live on less land makes the increasing construction of tall buildings inevitable.
The ability to continue to construct and access taller buildings has traditionally been driven by technological advances in elevators such as increased speeds and improvements in elevator traffic control.
New technologies such as regenerating drive systems, destination dispatch control systems, double-deck elevators and TWIN allow tall buildings to be constructed more efficiently than ever, making high rise development economically sustainable.
The elevator industry is a major factor in tall building construction. Every day there are more than 7 billion elevator journeys taken in buildings all over the world - the equivalent to the entire population of the world taking a daily journey in an elevator.
Elevators can consume up to 10 per cent of a high rise building's electricity usage. Increasing the efficiency of the drive systems can have a significant impact on the buildings carbon footprint.
Early steam powered and hydraulic elevators consume significantly more electricity than today's modern elevators.
Modern variable voltage, variable frequency drives consume less than one quarter of the energy consumed by hydraulic motors.
Regenerating drive systems return the energy of an elevator's downward journey back to the electricity supply, reducing the overall elevator energy consumption by up to 30 per cent.
Control systems which transport passengers efficiently to their destination with a minimum number of journeys and stops, combined with modern drive systems, make elevators increasingly energy efficient and sustainable.
With increasing land and construction costs, the key to building a modern skyscraper that is economically sustainable is increasing the building efficiency, which means reducing the size of the building core and plant spaces to optimize the yield.
As the service which occupies the most floor space in a building, elevators provide the greatest opportunity for space savings and efficiency improvements. Saving just one shaft can have a significant impact on a tall building's efficiency and the feasibility of the development. Recent elevator technologies offer further opportunities to improve building efficiencies by allowing the installation of fewer shafts while still achieving the same level of performance.
Double-deck destination dispatch in particular can provide substantial reduction in the number of elevator shafts in office tower developments, increasing the available area and potentially the value of the building.
TWIN elevators, meanwhile, can effectively be used to reduce the overall number of shafts in a wide range of tall buildings such as offices, hotels and mixed-use towers, while maintaining the same level of service.
Case Study: Rialto South Tower, Melbourne Australia.
The Rialto Towers are premium grade office towers located in Collins Street, Melbourne. Engineers from Meinhardt undertook the innovative design of the structure of these landmark towers over 30 years ago, and construction was completed in 1986. The Rialto South Tower remains the tallest office tower in Australia when measured to its roof.
The existing South Office tower comprises four passenger elevator services, including a total of 20 passenger elevators as follows:
- Low rise elevators (serving L1 to L12)
- Mid rise elevators (serving L12 to L24)
- High rise elevators (serving L24 to L37)
- Sky rise elevators (serving L37 to L54)
An alternative elevator design was considered for the tower utilising two banks of double-deck destination dispatch elevators, based on an equivalent level of performance to the original lift services.
Glen Pederick, discipline leader – building services at Meinhardt and a member of the Council on Tall Buildings and the Urban Habitat Advisory Board explained the new approach.
“For this alternative design, the low rise service would comprise 6 No. 1800kg double-deck destination dispatch elevators and would serve levels 1 to 29. The high rise service would comprise 6 No. 1600kg double-deck destination dispatch elevators and would be configured to serve levels 30 to 54,” said Pederick.
The service core for alternative double-deck destination dispatch design is compared with the original core design below:
“The alternative passenger elevator design requires 12 double-deck elevators, while the original design utilizes 20 passenger elevators. As a result, there are eight less elevators and eight less elevator shafts,” Pederick said.
Installing less elevator shafts provides the opportunity to gain floor area in the building. The alternative design allows an additional 2850 square metres of floor area for tenants of the building, which is the equivalent in area of almost three floors of the building.
With premium Melbourne CBD office space rental currently at $475 per square metre per annum, this extra space could provide an additional AU$1.35 million in annual rental income.
Premium Collins Street office space in Melbourne is currently valued at around AU $10,000 per m², so the additional value of the extra floor space in the building would be of the order of AU$28 million.