The rise and rise of VRFs

VRFs are fast becoming the cooling – and heating – option of choice for UK commercial building specifiers, taking share from chillers in the process.

Speaking to a range of suppliers in the sector, it is clear that continuing improvement the key areas of efficiency; ease of use – across design installation and user operation; and flexibility, thanks to compact footprints and a wide range of combination of units; are making VRFs the go-to technology for building designers in both new build and retrofit applications.

‘The efficiency gains, with improved ESEER and COP performance have been driven by product innovation in all the fundamental areas of the system: compressor, heat exchanger, use of refrigerant and controls. The forthcoming introduction of lower-GWP refrigerants, brought about by the European F-Gas Regulations, are expected to increase efficiency further.’

Whereas typically a chiller will have an ESEER of around 4, VRF systems now average over 6 and exceed 7 in some cases, the experts note.

Simplicity and ease of use is another strong driver. It should not be overlooked that VRF systems will often be packaged with their own sophisticated Building Management Systems (BMS) too, which avoids the level of integration that is required with chiller installations. In the words of one expert: “There is far more work involved in making chillers operate successfully with the separate BMS and so this only really pays off in very large systems.”

Manufacturers have made great headway in ensuring that the complexity of VRF systems do not translate into complex consumer controls, with a whole host of Apps and touchscreen control units launched to make the user environment as familiar as a smartphone.

Installers are increasingly drawn to this simplicity too: speed and cost of installation is another advantage compared either to a chilled water or all air system. One expert notes: “VRFs can be rolled out relatively quickly, with only small fridge lines and simple condensate pipe work to be fitted. There is no need for water treatment plant, pressurisation, filtration, venting or many of those other considerations with chillers.”

The sheer choice of permutations available with VRFs is another driving factor – creating unrivalled flexibility. If we add to this the fact that the equipment can generally be specified from available stock, as opposed to the usually built-to-order chillers, the advantages for specifiers continue to stack up. Also, a VRF installation can be achieved in stages, allowing building owners to avoid the high capital cost of a large capacity chiller.

New hybrid systems are expanding the application potential even further – combining VRF with hydronic modules enables a specifier to enjoy many of the benefits of chilled water systems, with a much more compact footprint from modular VRF units – which obviously helps with both installation and usage of operating space.

And it isn’t just cooling applications that now fall within the abilities of VRFs. The addition of heat pump hydro boxes to many VRF ranges is making them available for heating and cooling in what has traditionally been the territory of commercial air source heat pumps, or AC/boiler combinations. Let’s not forget also that VRF systems can be provided with heat recovery options, so there are opportunities for building owners to reap further efficiencies.

That isn’t to say of course, that VRFs are the cure-all for every application in the UK or that they are perfect, with experts pointing to the fact that non-chiller DX installations still sometimes struggle to get the cooling levels and air distribution right. One says: “It’s easy to forget that the whole idea of Air Conditioning for a specifier generally should be to make people comfortable, not to save money or to minimise the amount of equipment required; comfort is often better with the much more controllable and adjustable “traditional” cooling & heating systems.” Thus it requires careful attention to the controls system specification and installation

But it is clear that VRFs, in the UK, at least, are on the rise!