Bayou is a 2 000 m² sales floor on Houston's year with a 0.0095 kg/kg humidity ceiling, a prep room on a split, and a frozen store at −20 °C. The display cases are modelled as what they are — a negative gain, 35 kW sensible and 8 kW latent taken out of the room — which is why a supermarket's rooftops heat in the shoulder seasons and its night latent is negative.

Three gas rooftops each bringing their own 0.9 m³/s of outside air cannot hold the ceiling against some 80 kW of outside-air latent: on Houston's year the floor sits more than 3 % over it on 1 391 hours, 1 371 of them while the store is open, and the rooftops' furnaces burn 261 MWh of gas, half of their heat reheat for the ceiling they miss. A dedicated outside-air unit on the modular chiller — the DOAS scaled to 2.7 m³/s with a gas reheat — now leads the floor and the three rooftops recirculate behind it under the priority rule, so the unit carries the latent and the rooftops are asked only for the rest. Hours over the ceiling: 1 391 → 0 — and the building's cooling goes from 675 to 436 MWh, its electricity from 223 to 196 MWh and its gas from 261 to 203: the unit holds the ceiling for less of everything than the rooftops spend missing it.

That is the wheel's doing. The unit's recovery core is a sorption wheel (humidity efficiency 65 %, Eurovent 17/14's own worked figure, under the 73 % the certified sorption rotors read in summer), not a plate: on Houston's year the outside air's moisture is the load, and a wheel hands most of it back to the exhaust before the chilled-water coil sees it. Against the same unit on a plate core, the building's cooling falls from 715 to 436 MWh and its electricity from 265 to 196 MWh, the gas from 213 to 203, the floor held on its ceiling either way (10 hours more than 3 % over it on the plate). On a plate the dedicated unit would still hold the ceiling, but for more cooling and more electricity than the three rooftops spend missing it; the moisture recovery the recommendation describes for the humid Mediterranean, read here on the Gulf coast, is what makes it cheaper as well.

The frozen store is a unit cooler with both refrigerant ports open, fed by a Copeland ZF49K5E condensing unit on R404A drawn as its own block — the refrigerant coupling. A ZF25 was tried first and ran short on a 35 °C afternoon; the ZF49 holds the store between −20.0 and −19.9 °C every hour of the year at a seasonal COP of 1.10, the unit cooler cycling with its fixed-speed compressor.

What it reads on Houston

Cooling	436 MWh (most of it the outside air the unit brings in; 715 with a plate core in place of the wheel, 675 with the three rooftops alone)
Electricity / gas	196 MWh / 203 MWh (265 / 213 on a plate core; 223 / 261 with the rooftops alone)
Sales floor over its ceiling	0 hours more than 3 % over the 0.0095 kg/kg ceiling (1 391 with the three rooftops alone, 10 on a plate core)
Frozen store	−20.0 to −19.9 °C every hour; 55.5 MWh of unit-cooler duty on 50.5 MWh at the condensing unit — 45 K of suction superheat at the compressor, 8 of it the coil's
Prep room	held to the hour on its split; 658 humid hours, never 4 % over its 0.012 kg/kg ceiling — a split with no reheat holds it by over-cooling

What it taught

• Ventilation air is where the moisture arrives; drying it once at the door beats asking every rooftop to do it.
• A machine that leads a room carries its latent; the ones behind it are asked for the remainder — the priority rule has a moisture side.
• A cold store's condensing unit is sized for the hot afternoon, not the annual mean; pull-down margin of two to one is ordinary.
• Where the outside air's moisture is the load, a sorption wheel is worth two-fifths of the cooling: it hands the moisture back to the exhaust, and the coil is sized on what is left.

The machines

• Supermarket outside-air unit, 2.7 m³/s — open in the builder
• Recirculating gas rooftop, 3 m³/s — open in the builder
• Unit cooler, −20 °C store — open in the builder
• Low-temperature condensing unit, R404A — open in the builder

Sources

• Copeland Product Selection Software rating database (ZF49K5E on R404A)
• ASHRAE 55 humidity bound; ASHRAE 62.1 ventilation rates
• Eurovent Recommendation 17/14 (2025), Moisture recovery in ventilation and air conditioning systems; Eurovent Certified Performance, rotary heat exchangers (AARE)
• PVGIS TMY, Houston

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.