System Types & Applications9 / 17
Split Units & Multi-Split Systems
Indoor/outdoor splits, wall-mounted, multi-indoor, refrigerant piping.
10 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026
Walk past any UK office, shop or surgery and count the outdoor units on the wall: split systems are how most commercial buildings actually meet their cooling, and increasingly their heating. They are cheap to install, efficient when done well, and chronically mismanaged in practice. This lesson covers the configurations (single splits to VRF), what decides their real-world efficiency, and the operating habits that cost multi-split estates a fortune.
In this lesson
- 01From single split to VRF
- 02What decides real efficiency
- 03The estate problem: settings and fighting
- 04Sources and further reading