The words the app uses, each in a sentence, with the section that says more.
A machine whose only job is the ventilation air: 100 % outside air, recovered against the exhaust, dried once at the door and delivered neutral, the rooms' sensible load carried by other machines. Kinds of systems → Recovery unit and DOAS.
A machine serving one room that holds a supply-air setpoint, resets it upward as the load falls and slows its fan, so the room gets less air rather than warmer air. How a machine is run → Constant volume and SZVAV.
A room's own damper on a shared cold deck, metering its air between a minimum and a maximum and reheating at the minimum. Multi-zone VAV and terminal boxes.
The outside-air damper opened past its minimum on a cooling hour when the outside air is cooler, or carries less heat, than the return: free cooling. Economiser and outside air.
A plate exchanger between the cooling-tower loop and the chilled-water loop: when the tower makes water colder than the chilled-water return, the exchanger carries the load and the chiller idles — free cooling on the water side, the way the airside economiser is free cooling on the air side. A building run gives a plant with one a free cooling stage ahead of its chiller stage. See the plate exchanger.
The outside-air minimum following how full the rooms are, down to the per-area share and no further. Economiser and outside air.
A damper that sends part of the air across the coil and mixes the rest back; the coil dries the share it sees and the bypassed air is the reheat, for nothing. Humidity: ceilings and floors and the cleanroom case.
Condenser fans taken off on a cool day to hold a minimum condensing temperature — a constraint an expansion valve needs, not an economy. Head-pressure control.
A room's upper and lower bounds on moisture; the ceiling makes the machine over-cool and reheat (or bypass), the floor steers a humidifier. Humidity: ceilings and floors.
How a stage with too much capacity unloads: a fixed-speed compressor runs flat out for part of the hour, an inverter or a valve turns down. Cycling and modulation.
A join between two blocks at their open ports — water, air or refrigerant — carrying last hour's state across, one hour behind. Couplings between blocks.
The order machines serving one room take it in: the lead is offered the whole load and the latent, the next what the lead did not deliver. Several machines on one room.
What a system is — rooftop, split, air handler, chiller, condensing unit, fan coil, evaporative, recovery, plant, unit cooler, or a label of your own. Kinds of systems.
A saved or published system placed into a design as one block showing its open ports; the solver flattens it. Systems can contain systems.
One set of entering conditions the Design tab solves at; a typical meteorological year is the 8 760 hours the Simulate tab runs against. A solve is one condition; a simulation is a year of them.