Datum

01

The problem

My supervisor’s team ran five separate single-file HTML calculators. Nothing was stored, every calculation had to be saved locally by hand, and each tool had its own output format.

Datum puts all five on one signed, branded sheet that saves automatically to the cloud and files itself by job number.

02

Five engines, one platform

Each calculator is a pure engine, separated from the interface so it can be tested on its own.

• Pump Head: closed-loop hydronic head from segment friction (Darcy–Weisbach with Swamee–Jain, or Hazen–Williams), fittings and equipment losses, with automatic pipe sizing and velocity / friction-rate flags.
• Staircase Pressurisation: the ASHRAE orifice method and the BS 5588 leakage method side by side, for doors-closed and doors-open cases.
• Parking Ventilation: basement car-park exhaust and fresh air by air-change rate, with shaft, louver and fan sizing.
• Fresh Air & FAHU Capacity: ASHRAE 62.1 outdoor air per zone, plus psychrometric coil, heat-wheel and fan-power calculations to select the air-handling unit.
• Fire & Smoke Requirements: a rule engine for Dubai’s CDGH-OP-25 (Ch. 9 & 10) that returns sprinkler, riser, pump, pressurisation and smoke-control requirements with code references.

03

Accuracy first

All five calculation engines were ported unchanged from the original source to preserve engineering accuracy. A parity test suite then runs the new engines against the originals over roughly 5,500 randomised cases. It currently passes 18/18 with exact matches.

04

Accounts, saving and exports

Anyone on the team can open the shared link, create an account and start saving calculations. Supabase row-level security keeps each engineer’s sheets private, verified by a 15/15 security test suite.

The interface uses a drawing-style title block (project, job number, sheet, revision) with a results rail that updates live. Every calculation exports to Excel, CSV or JSON, or prints as a formatted, company-branded submittal sheet.