Station Park | 18, 28, 36, 43, 50 fl | U/C

[taylortbb]

You can build a building with a single-loop system (switchover spring and fall) or with a dual-loop system (separate heating and cooling pipes, no switchover). The dual-pipe system will cost somewhat more (don't know how much), and will cost somewhat more to operate (as both heating and cooling systems will need to run simultaneously).  So, yes, single-loop systems are still being built.

There's a middle ground option, the water source heat pump. It also uses a single loop, but instead of directly feeding coils in a fan coil unit, the loop is linked to the "outside" side of a heat pump. Then the heat pump can be used in heating or cooling mode. It provides the same flexibility as buildings that are built with heat pumps on the balconies, but none of the downsides.

That's why I'm surprised they'd setup a classic single loop system in this day and age. Just by putting heat pumps in you can get the flexibility, and the building system is largely the same.