Lakeside is one 1 660 m² floor from the DOE prototype: four perimeter zones and a core, DOE occupancy shape, 26.7 / 15.6 °C setback, optimum start, a 0.012 kg/kg ceiling. One packaged DX VAV rooftop serves it — an outside-air box with an economiser and a 62.1-pinned DCV floor, eight inverter modules on a 7 m³/s coil, a 60 kW electric warm-up heater, a supply fan holding 150 Pa of duct static, a two-fan condenser with head-pressure control — with a VAV box on every zone.

Three sizing lessons, all measured: three modules on 3 m³/s held none of the zones (the floor peaks near 70 kW at 90.1's densities and 32 m² of aperture); 6 m³/s left north and east short a dozen hours a week when every box's peak coincided; and boxes must be sized to each zone's peak with headroom rather than area share — south 1.8 m³/s against north 1.2.

On Chicago's year every zone is held to the hour — on the sun each façade actually sees, now that the rooms declare which way they face; on the horizontal scalar every wall is handed noon-strength sun and the same floor reads 3–8 unmet cooling hours a perimeter zone and 121 MWh of cooling against 106, and the six-module bank the rooftop first carried left the west zone 10 (7 Sep) — and 129 MWh of the 132 MWh of heating is reheat — the boxes' at their minimums and the ceiling's. That is what a VAV rooftop in a cold climate does, and the page says so.

What it reads on Chicago

Cooling / heating	106 MWh / 132 MWh (129 of it reheat)
Electricity	160 MWh
Zones	every zone held to the hour on the eight-module bank (six left the west zone 10 unmet cooling hours, 7 Sep)
Deck	13 °C reset to 18 °C from the critical zone (90.1 §6.5.3.5)

What it taught

• A box at its bare peak is short whenever the deck sits above its floor; size boxes to each zone's peak with headroom.
• A VAV box with a cooling load opens on the neutral deck on heating hours rather than parking at its minimum — or the core sits at 26 °C for 455 hours.
• A VAV handler makes its winter deck with its economiser, but only while some box is cooling; a cold deck otherwise is reheat for nothing.
• Which way a façade faces is worth more than its aperture: the same glazing reads 3–8 unmet cooling hours a zone on the horizontal scalar and none on the sun it sees.

The machines

• Packaged DX VAV rooftop, 7 m³/s — open in the builder

Sources

• DOE Commercial Prototype Building Models — Medium Office
• ASHRAE 90.1 Appendix G System 5; §6.5.3.5 reset
• PVGIS TMY, Chicago

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.