VAV versus VRV decline prophecy

[afak]

Hi to every One
I wish if we can make a comparison between vav and vrv systems looking at the advantage and disadvantages of them( suppose for the same building) from the coming points of views:
1. equipment costs:central and peripherals
2.installation time, costs, and difficulties
3.the meaningful of energy saving
4.the real importance of the money to be saved in the coming years comparison with the direct high costs of the system used and the impact of direct cash money to be payed for the costs of those intelligent complicated systems.
5.the amount of maintenance costs, troubles and dangerous for every system.

Which of the two expect to decline in the next years?

[Tesla]

Hi afak
3. It is logical on a large scale (building) to have both, and many buildings being built do. A VRV chiller with variable chilled water primary, variable chilled water secondary or fixed chilled water and VAV air side with floating static pressure. The above is most economical for medium to larger size buildings. For smaller low rise buildings and limited options, for life cycle costs are more favorable using only the VRV split systems. Over all the combination of the two systems can provide closest required conditions and efficiency. It's more a matter of cost effectiveness of the life cycle dependent on the size of the plant.

[frank]

VAV systems normally have a perimeter floor heating loop which adds to the cost and also humidity control problems.

The old VAV systems without VFD fan control were rather uneconomical to say the least.

[install monkey]

vav's are old, usually the operation of the bellows is via pneumatics or supply air- they are awkward to access.
also vav supply air has to be limited as above around 35deg the rubber bellows go brittle and then become noisy.
usually the vav master unit controls upto 2 slave vavs down stream and then some clever git sticks a partitioned office in where someone is always too hot/too cold- also you get the complaints of draughts in the morning ,then again vrv's can be a pain too in open office area's both systems are vulnerable when the outdoor unit dies, a section of the office is affected.
vav's are gonna decline in my eyes as theres not many about up north

[Tesla]

VAVs are plentiful in Sydney and other cities in Ausie with larger buildings. Sure you get more efficiency with a DX VRV Split type system (as a sub system). But when compared between a bunch of 20kW VRVs to a few 2000kW chillers with VRV the chillers win. On top of this the space it would take for the 100 or so DX VRVs compared to a 2000kW chiller. Each system needs to be looked at on a life cycle cost for various capacities. In a way many of the new VRVs use VAV. Both of these methods are needed for most efficient systems just using different machines for large or small loads.

[afak]

vav's are old, usually the operation of the bellows is via pneumatics or supply air- they are awkward to access
The Pneumatic Control has many problems.But the new vav systems resolve those problems using more intelligent methods to achieve less noise and more accurate controlling of the air flow. In stead of the Pneumatic Control they began to use an Electronic Control then advance to the direct digital control (DDC) boosted by micro processing and digital communication with possibility of PC monitoring and controlling .