Northgate is two data halls with 42 and 28 kW of IT around the clock on a computer-room air handler — a deep coil and a draw-through plug fan, no outside air, the halls' return on the coil — fed by the modular chiller holding 13 °C: a warm loop of the kind TC 9.9's A1 band permits. A UPS room sits on a remote condensing unit and an indoor DX unit cut along the refrigerant lines, and a NOC on the split.

Two things the first run taught: a 90 kW-class chiller ran flat out against 50 + 35 kW of IT, and a well-mixed hall at 25 °C on 14 °C water limits the CRAH to an 18 °C supply — 73 kW against 75 — so the halls hold 26 °C (A1 allows 27) on a 13 °C loop. In winter the indoor unit's economiser holds the UPS room on outside air while the condensing unit idles.

On Singapore's year the building reads 911 MWh of cooling on 260 MWh of electricity, the halls held at 26 °C every hour after the cold-start hour. Until 2 Oct it read 1 015 and 278: the NOC's split cycled through saturated hours, its room's humidity went out as no number at all, and the machine ran flat out all year against a room it could not read — 137 MWh of cooling booked for a room that needs 36.

What it reads on Singapore

Cooling / electricity	911 MWh / 260 MWh
Halls	26 °C every hour after the cold start
Loop	13 °C leaving water — an A1-band warm loop
NOC	24.0 °C all year on its split, 36 MWh of cooling (137 booked before the fix of 2 Oct)

What it taught

• A warm loop is a real design choice the model can price: 13 °C water, a deep coil, a hall at 26 °C.
• A refrigerant pair across two blocks runs one hour behind, like water: the indoor unit takes the feed the condensing unit reported last hour.
• Constant gains make every hour count — unmet hours around the clock, no setback, no schedule.

The machines

• CRAH, 8 m³/s chilled water — open in the builder
• Air-cooled chiller, 90 kW class — open in the builder
• Condensing unit, 12 kW class — open in the builder
• Indoor DX unit, 12 kW class — open in the builder

Sources

• ASHRAE TC 9.9 thermal guidelines (A1 band)
• PVGIS TMY, Singapore

Readings of the shipped model on the building's own PVGIS typical meteorological year; engineering estimates from catalog data and published correlations. The building runs on every plan, including Free, a few times a day.