1) What this calculator estimates
The calculator converts occupancy into expected simultaneous users, then applies an occupants-per-sink ratio. It supports design discussions and temporary works submittals. The output is a count of usable handwash positions; if you install troughs or multi-tap stations, convert them into equivalent positions.
2) Occupancy, shifts, and effective presence
When “total across shifts” is enabled, workers are divided by shifts to estimate concurrent attendance. Add visitors or other occupants who will use welfare areas during the same periods. For phased construction, size for the peak workforce rather than the project average. If the site has separate welfare points, run the tool per point to avoid under-sizing during peak breaks.
3) Peak factor and queue behavior
The peak simultaneous use factor represents break-time clustering. Values in the 50–80% range often suit typical sites, while synchronized meal breaks may justify higher peaks. If breaks are staggered, use a lower peak and note the rationale.
4) Ratio selection and allowance
The ratio (occupants per sink) is your main design assumption, so keep it consistent across submissions. Apply an allowance (often 10–15%) to cover uneven distribution, downtime, accessibility needs, and short-term spikes. Conservative ratios and modest allowances reduce waiting and improve hygiene performance.
5) Floors, zones, and placement checks
Use floors or zones to spread sinks closer to work fronts and welfare entrances. Set a minimum per zone when walking distance is a concern. Example: 120 workers, 20 visitors, 2 shifts, 70% peak, ratio 25, and 10% allowance gives 3 sinks, allocated 2+1 across two zones. Verify soap and drying provision, drainage, and at least one accessible station.
FAQs
1) Is this a code compliance tool?
No. It is a planning calculator that documents assumptions. Always confirm fixture counts and placement with your local regulations, client requirements, and project welfare specification.
2) What does “occupancy entered is total across shifts” mean?
If checked, workers are divided by shifts to estimate concurrent presence. If unchecked, the workers value is treated as the number present at the same time.
3) How should I choose the peak simultaneous use factor?
Use higher values when breaks are synchronized or welfare areas are centralized. Use lower values when breaks are staggered or zones are independent. Record the rationale in the project note.
4) Why is the result rounded up?
Fixtures cannot be installed as fractions. The calculator uses ceiling rounding to avoid under-sizing and to provide a conservative, practical count.
5) What does the additional allowance cover?
Allowance adds resilience for accessibility, uneven distribution, downtime, cleaning closures, and unexpected visitor spikes. It is a planning buffer, not a substitute for proper layout.
6) Can I use floors as work zones?
Yes. Treat “floors/zones” as welfare areas, wings, or work fronts. This helps allocate sinks to reduce walking distance and local queues.
7) What if minimum-per-floor increases the total too much?
Review whether zones are defined too granularly, or lower the per-floor minimum. Alternatively, keep the minimum and justify it for travel distance, accessibility, or critical hygiene areas.