It's one of the hardest things to fix once a building is finished: too few lifts and tenants queue every morning for the life of the building; too many and you've spent core space and capital you didn't need. Getting the lift count and size right at design stage is what lift traffic analysis is for.
What lift traffic analysis is
Lift traffic analysis models how a building's population moves through the day and tests whether a proposed lift group can cope — before anything is installed. It turns "how many lifts?" from a guess into a measured answer.
The numbers it produces
- Handling capacity — the share of the population the lifts can move in five minutes (offices are commonly designed for around 11–15%, depending on grade).
- Average waiting time — how long people wait for a car; the headline measure of service quality.
- Time to destination and lobby interval — the full door-to-door experience, not just the wait.
Demand profiles — the patterns that matter
A demand profile describes how many people want to travel, in which direction, at a given time. The same lift group can sail through one profile and choke on another, so a proper analysis tests several:
- Up-peak — morning arrival: almost everyone is travelling up from the lobby at once. For offices this is the classic sizing case — handle the up-peak and you usually handle the rest.
- Down-peak — end of day: the flow reverses, with everyone heading down to the lobby.
- Two-way / interfloor (lunch) — midday: people travel up, down and between floors all at once. Often the hardest pattern, because the cars can't simply shuttle one way.
And the dominant profile depends on the building's use:
- Office — up-peak drives the design; the lunch two-way peak is the stress test.
- Residential — a morning down-dominant flow (people leaving for work) and an evening two-way flow.
- Hotel — two-way through the day, with check-out (a morning down surge) and check-in (an afternoon up surge) as the pressure points.
A good analysis runs the profiles that matter for the building's use — a design tuned for the morning rush can still leave people queuing at lunch.
Conventional vs destination dispatch
How the lifts are controlled changes the answer. Conventional collective control sends the nearest car to each landing call; destination-group dispatch groups passengers heading to similar floors into the same car, cutting stops per trip. Destination control can lift performance most in busy, stop-bound buildings — but the only way to know the real difference for your building is to simulate both on the same demand.
How it's done
Fast analytical estimates give a first read; a Monte-Carlo simulationthen runs realistic passenger demand through the proposed design and measures what actually happens. Everything is grounded in published engineering — ISO 8100-32:2020, CIBSE Guide D, and the PCA Office Quality Grade Matrix — so the result is auditable, not a black box.
A note on standards: PCA vs CIBSE vs ISO 8100-32
Three reference frameworks shape lift traffic design, and it helps to know what each one actually does:
| Framework | What it sets | Where it fits |
|---|---|---|
| PCA Office Quality Grade Matrix Property Council of Australia | Design demand and waiting/interval targets tied to a building's quality grade (Premium, A, B…) | The Australian benchmark a design is graded against |
| CIBSE Guide D UK design guide | Recommended handling capacity and interval / waiting time by building type and desired quality — and the round-trip-time calculation method that produces them | The design-stage reference for sizing, and the published basis for the calculation |
| ISO 8100-32:2020 International standard | A standardised simulation method and verdicts — under-sized, close to the limits, properly sized, or a robust design with sufficient capacity — for defined office, hotel and residential demand templates | The formal international benchmark for verifying a design by simulation |
They reason about the same peaks but differ in the exact arrival rates they assume and the waits they call "good" — so a design can pass against one and sit borderline against another. In short: PCA sets the grade a design is judged against, CIBSE Guide D provides the sizing recommendations and the round-trip-time calculation behind them, and ISO 8100-32 provides the simulation method that verifies the result.
When to do it
At feasibility and design stage, to size the lift group before the core is fixed — and again whenever a building changes use, adds floors, or modernises its lifts.
Model it yourself
You can run all of this in Traffic Studio — model office, residential and hotel demand profiles, compare conventional and destination dispatch on the same demand, and grade the design against PCA and ISO 8100-32, right in your browser.
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