Cost Model: Lifts & Escalators Costs can vary widely for different solutions but  the key is to strike a balance between the value of floor area occupied and the system’s performance criteria, writes David Hughes at Davis Langdon Landings and lift lobbies are often a focal point of a building's design, required to emphasise its communication routes. Planning for vertical transportation is also a key engineering design issue and certain decisions need to be taken early in the design process. Costs of different solutions can vary widely, and it is important to strike a balance between capital, value of the floor area to be occupied by the lift shafts and lobbies, and performance criteria such as waiting times. The lift and escalator industry, in common with many other industries is constantly refining its product ranges in response to advances in technology, the demand of its customers, changes in regulations governing the industry both in Ireland and abroad, and to gain a technological edge over competitors. The past 10 years have seen significant developments with the industry. There are currently two main types of lift drive system available – electric traction drive and hydraulic drive. The use of the latter is in decline with the advances that have been made in traction drive in the last few years. A number of factors should be considered when evaluating which is the more suitable option for a particular project. The most important variables to consider are the number of people to be transported, desired passenger waiting times and frequency of use. ELECTRICAL TRACTION LIFTS Modern traction drive lifts provide high performance without the need for frequent maintenance such as lubrication and adjustment. They may be categorised as follows: Machine room-less Most modern lifts are arranged with the drive motor mounted within the shaft and the controls housed in a compact panel adjacent to a door, thereby removing the need for a separate machine room. MRL units now dominate the low and medium-rise passenger lift market and this trend is set to continue as designers recognise the following performance advantages:

Passenger comfort and accurate landing levelling – especially with regard to the needs of people with limited mobility and recommendations from Part M of the Building Regulations; Energy usage and whole life costs – where traction drives are superior, not least because of the energy-saving advantage resulting from the counterweight; Flexibility in car dimensions, maximising the utilisation of the shaft resulting in the capacity to carry larger volumes; Manufacturers continually expanding the capabilities of these units; The MRL may have some operational disadvantage with regard to ease of access for maintenance but this is considered to be outweighed by its advantages.

With machine room For projects with more exacting performance criteria in terms of travel height and speed, there is no alternative to having a machine room, which may be arranged above, below, or, exceptionally, to one side of the lift shaft. Gearless technology Gearless technology was previously used primarily in high-rise lift installations that require greater travel speeds with medium passenger loads but is now used for most installations. Geared traction systems were historically used in some mid-applications with high-rated loads and lower speeds but are not used to any great extent today. Variable voltage frequency Variable voltage frequency (VVF) controllers provide smooth acceleration and braking of the lift car (thus improving passenger ride comfort while enabling quick and efficient travel between destinations), together with precise car levelling at floors. HYDRAULIC LIFTS The use of hydraulic lift technology is in decline. It is optimised for low rise, low-usage installations where moderate car speed is acceptable. This is normally used on building applications with heavy loads, including freight, goods or lift application (i.e. vehicle lifts). The direct acting system normally requires a borehole to accommodate the hydraulic ram which is fixed to the underside of the lift car. For “indirect acting” hydraulic systems, the cylinders and pistons are arranged vertically and a remote control centre can respond immediately and proactively to any incidents or faults. Innovation for tall buildings A recent breakthrough development in technology is the concept of two lift cars running independently in a single shaft. This simple concept, called TWIN, offers significant space-saving advantages inside a building by eliminating one lift shaft while providing increased passenger-handling capacity. Coupled with hall-call destination control (which allows passengers to select their destination floor before entering the lift), TWIN technology challenges conventional traffic analysis constraints – offering the opportunity to increase the lifting capacity in previously “under-lifted” buildings as occupancy levels are increased – in a refurbished office design or change of use, for example. The TWIN concept is currently available from only one manufacturer, and has not yet been applied to a project in Ireland. The “double deck” concept, which is better established than the TWIN system, also makes very efficient use of hoist way space. This consists of two lift cars, powered by a single electric traction drive, which move together, serving odd and even floors simultaneously. Where this type of lift is used, special arrangements must be incorporated within the building to route passengers to the lift car that will serve their destination – these could include stairs or escalators and the building entrance hall. Similarly, the control system needs to prevent time wasted during off-peak journeys by matching destination floors to car stop commands. The rule of thumb for double deck to operate efficiently is a zone of around 15 to 18 levels for each group though this is wholly dependent on the building layout. Group control Many of the major manufacturers have developed hall-call destination control systems. Each request is analysed by the control system and the passenger is assigned to the lift that will result in the quickest journey. By reducing intermediate stops and empty car runs, the handling capacity can be increased by up to 30% compared with conventional controls. The latest systems can respond to patterns of travel in the building, resulting in more efficient use of the lift group and reduced passenger waiting times. Group control can be particularly effective for refurbishment projects, where it may be possible to provide improved service without increasing the number of lifts in a building. ESCALATORS Escalators are very effective in moving large numbers of people slowly with no waiting time, but are relatively expensive and occupy a large amount of floor spacing compared to lifts. Their usual range of application therefore includes airports, retail parks and department stores, leisure centres and high-density office areas such as trading floors. A limited range of functional options may be specified, including step width, elevation angle and travel speed (normally 0.5 – 0.75m/s). Aesthetic and enhanced functional finishes can be incorporated in the design, such as concealed lighting, balustrades material, handrail type and cladding material.

David Hughes Davis Langdon PKS Several factors combine to influence the cost of a lift installation, including the requirement for and location of a motor room (MR or MRL); intelligent car group control; number of floors; fire-fighting; thru car; isolated installations – grouping of lifts most economical; number of openings per floor; passenger capacity and finishes and facilities. Davis Langdon PKS has been involved in a large number projects with lift and escalator installations throughout Ireland. This database of information has been used to generate the cost model above, based on a standard sizes and finishes. Rates are using August 2008 as a base date.