The Property Council of Australia Guide to Office Building Parameters provides a simple design specification for new office buildings. The specifications for lift design are based on an up peak traffic calculation with performance parameters as set out below:
Property Council Lift Performance Parameters for Offices
Description Handling Capacity Waiting Interval Min Car Capacity
Premium >= 15% in 5 min <= 25 seconds >= 21 persons
Grade A >= 14% in 5 min <= 30 seconds >= 16 persons
Grade B >= 12% in 5 min <= 35 seconds
Car Load factor <= 80%
Population: 1 person per 12M² NLA
The guidelines are not specific in the setting of calculation parameters such as lift acceleration and jerk rates, door opening and close times or passenger transfer times. In some instances these parameters may have been maximised, within achievable but not necessarily practical settings, in a calculation to get an otherwise effective lift solution in line with the PCA Guidelines.
Advances in elevator technology have seen the introduction of systems, such as the KONE Polaris Destination Consultation System, which allow passengers to select their intended destination from the lift lobby and be directed to the lift that will take passengers to their intended destination with the minimum number of stops. The advantage of a Destination Consultation System is that, whilst a passenger may wait a little longer in the lobby, the total journey time is significantly reduced as a result of the smaller number of stops.
Whilst the KONE Polaris Destination Consultation System provides a significant boost to up peak performance, this boost is not directly proportional to that achieved in other traffic scenarios such as two way and lunch time peak. When considering a lift solution that requires the use of up peak boosting, to meet PCA Guidelines, it is important to also check the lift performance in other traffic scenarios to ensure that the lift system can provide a balanced and efficient people flow throughout the working day.
If optimistic lift performance parameters have also been included in the traffic calculations this will be compounded by the addition of up peak boosting and the relevance of the calculations to real life traffic flow requirements may be further compromised.
When starting an Grade A Office design from a brief, where information is often limited to the number of levels to be served and the approximate NLA on each level, we would generally start with a conventional traffic calculation with default settings as follows:
- Lift Car Capacity: 21 – 24 passengers
- Lift entrances: 1100 - 1200 mm wide with 2pc doors
- Door Closing Time: 3.1 seconds for 1100 mm doors / 3.4 seconds for 1200 mm doors
- Door Open Time: 1.4 seconds to 800 mm open
- Passenger Transfer Time: 1.6 – 2 seconds in and out
- Speed selected for a nominal travel time of between 20 & 25 seconds over the travel
- Acceleration Rate: 1.0 m/sec²
- Jjerk Rate: 1.6 m/sec³
You may find that a preferred lift grouping, that is otherwise quite practical, just falls short of the PCA guidelines with the default settings and that the addition of another lift places the lift performance well above what is required for the target market. Depending on the situation changes to parameters such as, lift car size, door times and or acceleration rates may be enough to bring the calculated lift performance well within required PCA Guidelines. All parties should be aware that the calculated lift performance will be at the lower end of the scale for the chosen Building Grade and that there is little if any room for additional NLA or travel to be added to the project.
The addition of a KONE Polaris Destination Consultation System may be considered for a number of reasons including the following:
1. The Destination Consultation System is the latest in lift allocation technology and may fit well into the high tech image required in modern high rise CBD Office designs.
2. The lift lobby layout may restrict vision to all lifts and the DCS system will guide the passengers to the relevant lifts.
3. All lifts in a group may not serve all floors and the DCS system will allocate the correct lifts to take passengers to these floors.
4. When a double deck lift solution is required the DCS system is required to provide effective allocation to the top and bottom lift car levels.
5. Where a lift selection is close to providing the required level of up peak performance the introduction of a DCS system may boost up peak performance to meet the required guideline. To ensure that the lift design is capable of meeting people flow requirements, throughout the working day, lift performance in other traffic scenarios should always be taken into account when using a DCS solution for this purpose.
When looking at a design for a Grade A Building which is to include a KONE Polaris Destination Consultation System we use the following philosophies to ensure an effective lift solution.
1. The base conventional lift design should use realistic parameters and be within 2% of meeting the required level of up peak performance from the PCA Guidelines.
2. The Destination Consultation System should not be used to eliminate lifts from the group unless the simulated lunch hour and two way performance is at an acceptable level.
3. With a 14% - 15% up peak handling capacity time to destination is less than 80 seconds.
4. With a 17% - 18% up peak handling capacity time to destination is less than 120 seconds.
5. With a 14% handling capacity two way waiting times should not go much over 30 seconds.
6. With a 14% handling capacity lunch hour waiting times should not go much over 30 seconds.
7. Lift parameters such as speed, car sizes and door width should be commensurate with the image, technical and practical requirements of the buildings intended market.