Key design considerations for lifts and escalators in offices - part 3 lift design for the redevelopment of existing office buildings

By Graham Barker

Part one covered lift design considerations affecting building layout and space take, click here to read part one.

Part two covered making the right choices during lift design, click here to read part two.

There are many key design considerations for lifts and escalators in offices which are consistent across all projects, in Part 3 we’ll focus on lift design associated with the redevelopment and refurbishment of lifts and escalators in existing office buildings:

• The challenges of lift design for existing office buildings
• The importance of lift and escalator feasibility studies for existing offices
• Suitability of the existing office lift provisions
• Opportunities to increase building population density
• Escalator constraints

The challenges of lift design for existing office buildings

For new office developments, the vertical transportation design has the luxury of not being restricted by an existing structure. Instead, the key consideration is minimising the building area occupied by the lift cores and lobbies to maximise the net lettable area. Every square foot or metre given over to lift shaft is space that can’t be leased to a tenant.

In an existing building, the cross-sectional area of the lift shaft is typically a restriction due to the significant structural works, and therefore costs, which would be needed to move lift shaft walls. Frequently existing building will be increased in height with the addition of extra floors, and the lift shaft extended. Similarly, lift shafts may be excavated to increase their depth, or to enable the lift to serve new basement levels.

In any case, the constraints of an existing building often increase complexity and require a slightly different approach to that applied to new build development.

The importance of lift and escalator feasibility studies for existing offices

In an existing building, the first action should be to engage a lift consultant to undertake a feasibility assessment which will identify restrictions or limitations imposed by the structure on any lift or escalator works, and determine the areas where challenges may exist complying with latest regulations and standards. In parallel with this, the lift consultant will consider the architect or developer’s plans and pull all these inputs together to provide advice on realistic opportunities which will help in delivering the overall aims of the development.

The lift and escalator survey and feasibility assessment can often form part of the developer’s due diligence when considering purchasing a property, with the lift consultant often surveying the existing lift provisions as part of the acquisition process providing advice on the feasibility of future vertical transportation modifications.

Some examples of challenges a lift consultant may face for existing buildings include:

• Addition of new lower floors, associated with the excavation of the lift pit
• Addition of new upper floors and extension of the lifts to serve them
• Extending existing lifts to serve what was previously the roof level to activate the roof
• Increasing the size or speed of lifts to improve the buildings lift capacity without structural modifications
• Change lifts to a machine room less arrangement to release the area previously occupied by machine room
• Assessment of options to extend the lifespan of the lift whilst minimising capital investment
• Replacement or refurbishment of aged escalators which are landlocked

The feasibility assessment will inform the developer if their plans are deliverable within the envisaged budget and programme. The long lead time and high capital costs associated with lift works can have significant impacts on the projects on-time and on-budget success if not correctly planned for from the start.

Suitability of the existing office lift provisions

In most existing office buildings, the key initial consideration regarding lifts and escalators will be the suitability of the equipment for the intended use, the remaining life span of the equipment, and any significant capital expenditure which will be needed.

Opportunities to increase building population density

Over time the way that offices are used has developed. And the theme over recent years has seen office population density increasing placing greater demand on the lift system. It is important to assess the potential for existing office buildings, and lift systems, to handle this increased building population and to ensure that lift waiting times will be acceptable. This is an area where your lift consultant can couple a lift performance measurement survey with lift traffic analysis simulation to assess the suitability or limitations of the existing equipment.

Taken to the next step, performance measurement of existing lift systems can also identify ways in which a lift system’s performance can be improved – be it by tuning of the existing system, or through targeted lift modifications and upgrades to deliver enhanced lift system performance with minimal intervention or capital investment. In a recent project, performance measurement of the existing lifts identified minor adjustments which could be made to the setup of the existing lifts, delivering marked improvement in lift performance, allowing the lifts to achieve BCO compliance even though the occupancy of the building increased.

Escalator constraints

Escalators are usually inserted into a building as part of the building’s construction sequence, often being installed before surrounding walls and floors.. An escalator in a need of refurbishment or replacement will need to be managed differently.

In this scenario there are generally three potential solutions:

1. A complete replacement can be undertaken when the escalator can be removed and a new unit brought into the building. If the escalators are located adjacent to the building entrance, or in an atrium this replacement can be undertaken easily.. However, the further into the building an escalator is, the bigger the challenge becomes of removing it.
2. Where removal is not an option, then refurbishment of the existing may be considered. The various wear components of the escalator are removed and either reconditioned or replaced with new.
3. Over recent years the concept of ‘in truss replacement’ has been developed where the escalator internals are stripped out leaving only the structural escalator shell. Then through detailed surveying and design, a new escalator is engineered and manufactured to fit within the original structure.

Its fair to say that no two escalator projects are the same and each needs its own detailed assessment of the available options, which are a factor not only of the escalator equipment but more significantly of how the old and new escalator equipment can be brought to site.

Lift and escalator consultancy for office developments

There are many ways in which a lift consultant can help to improve the value and operation of office buildings, through the thoughtful specification of the vertical transportation equipment.

This series of blogs aimed to provide some thoughts, coupled with experience from previous projects, to assist with the reader’s future building designs and the associated lift and escalator design considerations. To discuss in more detail please don’t hesitate to contact the writer or comment below.