The daikin VRV III is a good choice if engineered and installed correctly. As stated before, they have water cooled available as well, and they can heat and cool at the same time (Re-Heat models). This improves energy efficiency.
They also have an option where Daikin monitors operating conditions and local weather forcasts, and they remotly adjust the operating perameters for maximum energy efficiency. For example, on hot, dry days they may adjust the suction pressure setpoint higher, lowering latent removal but maintaining comfort conditions.
On a moist day, they may lower the suction set point to allow more latent removal.
Daikin claims they can achieve up to 20% more energy savings this way.
VRV-IV has been released in the UK, and it allows heating and cooling at the same time, and even continuous heating while in defrost.
Another nice feature is their I-Touch / I-Touch Manager building management system. All systems can be controlled from one place, with remote access and e-mails, and scheduling.
Other things such as lighting can easily be hooked in to this control system.
The HVAC contractor can install it all. They may need a little help with the commissioning. The system can also tie in to existing BMS systems.
We have been designing, installing, servicing and maintaining these systems for over 8 years.
In that time, we ave had exactly one compressor failure (DOA on origional start up) and one condensing coil leak on a 4 ton VRV-III-S. That is it.
Maintenance is easy if the space requirements are followed. The air filters they supply are not good.
Another idea is to use Daikin/McQuay water source heat pumps. They have a some that use the same VRV technology in a self contained unit. They tie in to the same communication bus as the VRV systems.
Daikin / McQuay also makes a packaged unit called the "Rebel" that is great for 100%OA treatment. It also ties in to the same BMS line.
Another nice feature is fire alarm circuits only have to be brought to one place to shut down the entire system. This can save a lot of money.
Generator loads can generally be smaller as well because you can have the hvac systems run in a limited mode, and there is no inrush current. Many times we have saved electrical services from having to be upgraded as well.
We work on a wide variety of equipment, from residential to chillers and everywhere in between. We have found the Daikin VRV to be the most energy efficient in our area, and among the most if not the most reliable.
I will tell you, when designed, installed, and commissioned improperly they are a nightmare.
I have had to go in and re-design a few systems.
The big thing with maintenance is to not let people put gages on the systems. It won't tell them anything.