A 60-unit mid-rise building where per-unit PTHP equipment is weighed directly against a diversified central plant, and corridor pressurization introduces the program's first shared, code-driven ventilation problem.
The project brief: a 5-story, 60-unit apartment building, each dwelling unit conditioned by its own packaged terminal heat pump, with shared lobby, corridor, and amenity space conditioned separately. This module calculates loads for three representative unit types, selects PTHP capacity per Manual S against fixed equipment increments, and works a full side-by-side comparison — 52.0 tons of installed PTHP nameplate capacity versus 39.1 tons of diversified central-plant capacity for the same 60 units.
It closes with a worked corridor pressurization calculation — sizing a central makeup air unit to 110% of aggregate unit exhaust airflow to keep the shared egress corridor positively pressurized relative to every unit — the first life-safety-driven ventilation problem in this program's real-project sequence. The full worked numbers, bill of materials, and design reasoning are part of the unlocked module below.