HVAC System with VRV or Chiller System is Cheaper ? 1

[JoeH78]

dear ALL,

Let's assume that we have the same square meter of area to be cooled(e.g. 1200m2) using the same heating cooling loads and design principles will the VRV system or using one outter chiller model be more efficient in terms of cost? ]

 

[HVAC-Novice]

You need to perform an energy simulation. this depends on climate, the use profile, type of facility, enclosure and local energy cost. And it also depends on the specific equipment. You won't believe it, but they make more than one type of chiller and pumps

 

[JoeH78]

@yes I know, but which one would be more cost efficient since the input is same for both of the system? They are in very same location, same building, why would one be prefering to use VRV instead of chiller based system or vice versa.

 

[JoeH78]

I was exepecting something more like that, but from human

User
advantages of VRV system over chiller based systems ?
ChatGPT
VRV (Variable Refrigerant Volume) systems and chiller-based systems each have their own advantages and are suitable for different applications. Here are some advantages of VRV systems over chiller-based systems:

Energy Efficiency: VRV systems are often more energy-efficient compared to chiller-based systems, especially in partial load conditions. VRV systems can modulate their capacity based on the actual cooling demand of the building, leading to reduced energy consumption.
Zoning Flexibility: VRV systems offer greater zoning flexibility, allowing different areas or rooms within a building to be cooled or heated independently. This can lead to better comfort control and energy savings by avoiding overcooling or overheating of unused spaces.
Compact Design: VRV systems typically have a more compact design compared to chiller-based systems, which require large chillers and associated equipment. This can be advantageous for buildings with limited space for mechanical rooms or outdoor equipment.
Installation Flexibility: VRV systems are easier to install and retrofit compared to chiller-based systems, especially in existing buildings where space and access may be limited. The modular design of VRV systems allows for easier transportation and installation of indoor and outdoor units.
Quiet Operation: VRV systems generally operate more quietly compared to chiller-based systems, which may have noisy compressors and cooling towers. This can be beneficial for buildings where noise levels are a concern, such as residential or commercial areas.
Individualized Control: VRV systems allow for individualized control of temperature and airflow in different zones or rooms, providing occupants with greater comfort and flexibility.
Improved Comfort: The precise temperature control and zoning capabilities of VRV systems can lead to improved comfort for building occupants, as each area can be maintained at its optimal temperature without affecting other zones.
Integrated Heat Recovery: Many VRV systems offer integrated heat recovery capabilities, allowing for simultaneous heating and cooling within the same system. This can improve overall energy efficiency by recovering waste heat from areas requiring cooling and using it to heat other areas.
While VRV systems offer several advantages over chiller-based systems, it's important to consider factors such as initial cost, maintenance requirements, and suitability for specific building types and applications when selecting the most appropriate HVAC system.

User
disadvantages ?
ChatGPT
While VRV systems offer numerous advantages, they also have some disadvantages compared to chiller-based systems:

Initial Cost: VRV systems typically have a higher initial cost compared to traditional chiller-based systems. The cost of the equipment and installation may be prohibitive for some projects, especially for larger buildings or those with high cooling/heating loads.
Complexity: VRV systems can be more complex to design, install, and maintain compared to chiller-based systems. They require careful consideration of system layout, refrigerant piping, and control strategies to ensure optimal performance.
Refrigerant Piping: VRV systems rely on refrigerant piping to connect indoor and outdoor units, which can be challenging to install in existing buildings or structures with limited space. Proper sizing, insulation, and routing of refrigerant piping are critical to avoid performance issues and refrigerant leaks.
Limited Capacity: While VRV systems offer flexibility and modulation of capacity, they may have limited capacity compared to chiller-based systems. This can be a drawback for buildings with high cooling/heating loads or those requiring centralized plant systems.
Outdoor Unit Noise: While VRV systems are generally quieter than chiller-based systems, the outdoor units can still produce noise during operation. In noise-sensitive areas or residential applications, the sound of outdoor units may be a concern and require mitigation measures.
Maintenance Requirements: VRV systems require regular maintenance to ensure optimal performance and reliability. This includes cleaning filters, inspecting refrigerant piping, checking for refrigerant leaks, and servicing components such as compressors and fan motors. Improper maintenance can lead to reduced efficiency, system failures, and increased operating costs.
Compatibility Issues: VRV systems may not be compatible with existing HVAC infrastructure or building control systems, requiring additional integration efforts and potentially increasing project costs.
Dependence on Electrical Power: VRV systems rely on electrical power to operate compressors, fans, and control components. In areas with unreliable power supply or frequent outages, this dependence on electricity may be a drawback compared to chiller-based systems that can use alternative energy sources such as natural gas or district heating/cooling.
Despite these disadvantages, VRV systems remain a popular choice for many applications due to their energy efficiency, flexibility, and comfort benefits. Careful consideration of project requirements, budget constraints, and maintenance considerations is essential when selecting the most appropriate HVAC system for a building.

 

[HVAC-Novice]

You should hire an HVAC engineer familiar with both. and you probably should provide them with more information than you did here or to ChatGPT.

So many variables and there is no single answer. For starters, a chiller could employ an AHU with VAV, or FCU and DOAS. or a combination of both. Chiller can be air or water cooled. and based on size it can be a centrifugal or other chiller. VAV systems also can use economizers. There also are installation and maintenance considerations. VRF is proprietary and requires refrigerant lines throughout the building. There also are maximum allowable line lengths.
Is this a whole 20 floor office building or a single office suite, what are hating needs... all that matters.

A well designed VAV system can be more efficient than VRV.

 

[BronYrAur]

First cost? Operating cost? Too many variables. Is this just one large open space? Office? Warehouse? number of zones? Required ventilation?

You need more information to make that decision.

 

[SAK9]

VRV system will be obviously cheaper. You can save more by using ductless systems. There is also cost saving as the VRV system comes with its own control system so you may not require a full on building automation system required for chilled water systems

 

[HVAC-Novice]

It isn't "obvious" which system will be cheaper (if by cheaper you mean upfront cost). and you still need duct for ventilation and exhaust. You also need controls for ventilation and if you are in any type of humid climate you need OA cooling. And the VRV controls are not "free" you pay for them as part of the package.
It also isn't clear if and what heating is required.

Can VRV be cheaper? Yes. But this can't be a blanket statement on basically no information given in the OP.

 

[dbill74]

My experience has been that VRV's tend to be more energy efficient.
That said, they aren't without other problems and complications.
For one, they still need an DOAS unit and duct for ventilation air.
Depending on your locale, the size of the system can have limits set on the amount of refrigerant in the system requiring multiple VRV systems.
Not every maintenance person knows how to or is qualified to work on VRV systems.

In response to ChatGPT's VRV Advantages;
[ul]
[li]Energy Efficiency: I agree, it isn't huge, but yes.[/li]
[li]Zoning flexibility: Completely disagree. Both system types are equally zoneable. In some ways, VRV can be more restrictive due to their limited zone sizing. Chilled water with VAV system can have massive zones 1,500+ square foot zones alongside 100 square foot offices. I don't know if VRV can do that.[/li]
[li]Compact Design: Again, disagree. There are trad-offs in the design. I can think of one building that used VRV where the yard for the condensing units is 3-4 times that needed for an air-cooled chiller or cooling tower.[/li]
[li]Installation flexibility: Not as flexible as ChatGPT makes it out to be I think. When internal space is very limited, VRV can be advantageous.[/li]
[li]Quiet Operation: Disagree here. Inside a building, a VAV system can be quieter than VRV which has fans in every room. As for chillers or cooling towers, there are ways to mitigate the noise, and VRV will have condensing units outside making noise.[/li]
[li]Individualized control: Same as zoning flexibility, no difference.[/li]
[li]Improved comfort: Disagree, actually give this to the chilled water system for not needing separate OA duct running throughout the building.[/li]
[li]Integrated Heat Recovery: Not sure I buy this one. It is rare that one part of a building needs heat while another needs cooling at the same time. Yes VRV can do it, but is it worth it?[/li]
[/ul]

You need to hire someone to do a complete LCCA including energy simulation in accordance with ASHRAE 90.1 Appendix G.

 

[HVAC-Novice]

dbill74 is right and re-enforces the " it depends".

Heat Recovery can be beneficial if you have internal rooms that require cooling in heating season. but with no information given, it is hard to tell. and if you live in moderate climate, VRV can provide heating as a heat pump. but this doesn't work in cold climates and you need separate heating (fuel, electric). Again, it depends.

For energy efficiency, yo really need to do a good energy simulation. With VAV you can control ventilation and cut it off in unoccupied rooms or modulate it in meeting rooms. with a VRV, you usually have a CV system and every room gets the design ventilation all the time, even if unoccupied. unless you make this a VAV system. but then the upfront cost goes up.
for VRV you also need to meet ASHRAE 15 and this requires many ducted units. so you add a lot of small fans and ducts. Small fans = less efficient.

To muddy the water even more, you also can use water-based VRV and use geothermal etc. You cannot just eye-ball this and collect some opinions from strangers off the Internet.

I once performed an energy simulation comparing a VAV to VRV and the VAV actually was more efficient when using high efficiency VAV design. WE are in a heating climate and this was a small building with littler core cooling needs.