Arguably, the most popular systems for medium to large commercial projects are now VRV or VRF systems, these are modular heat pump or condensing units connected to a number of room mounted fan coil units. The systems use copper pipework distribution systems to connect all the components. Refrigerant is used to provide both cooling and heating and electricity is used as the power source.
These systems are inherently very reliable and very efficient and provide extremely economical running and owning costs because the capacity of each system is matched to the load by varying the refrigerant volume (VRV) or flow (VRF).
VRV/VRF systems provide year round heating or cooling if required, so you do not need a boiler and radiators if a heat pump is used.
Many options are available with various means of controlling, both locally, centrally and remote, you can have cooling only, cooling and heating or heat recovery. Heat recovery can be used in some buildings to reduce fuel consumption by recovering waste heat from zones that need cooling to others that may simultaneously require heating.
Split systems can serve single rooms or areas, either cooling only or heat pumps.
Multi-split systems effectively are smaller versions of VRV and VRF and can be designed to serve up to 7 small rooms or areas.
Chilled water fan coil systems use a central water chiller providing chilled water to any number of room mounted fan coil units. Heat pumps are also available but more commonly 2-pipe systems only provide cooling as heating is dealt with by an existing heating system, or 4-pipe where a boiler is used to also supply hot water to the same room fan coil units.
Variable water temperature (VWT) systems have a common two pipe water distribution system to which are connected room or zone mounted terminal units (effectively a fan coil unit but also with a refrigeration compressor) that are heat pumps. The central plant comprises a cooling tower or other heat rejection device plus a water boiler. The temperature of the water circuit is adjusted by the central plant to suit prevailing conditions and the terminal units then adjust the required heating or cooling to suit the room requirements.