Aircon Diversity

[ecodian]

I have a question on Aircon diversity.
1. If the cooling load for the hotel is calculated to be 2000 tons, what is the normal diversity used for the design?
2. Supposed we used 75% as the diversity, should the main pipe and the branch pipe be size according to the diversity?

[Abby Normal]

you have the diversity of the occupancy, as well as the diversity of the time of day

I would start by going back to how 2000 tons was calculated and see the time of day that the load peaks at.

It most likely peaks late in the afternoon, so west zones are at a maximum, maybe the east zones are at 50%, central zones constant.

Then grow a set as to derate for less than peak occuopancy

THe outdoor air temperature does not matter too much where you are, what will matter is how sunny it is and how humid it is

Check the months of decrmeber out if you have lots of south facing glass, assuming you are north of the equator, I am a little rusty on my geography these days

approach it likre it was a diakan vrv job

[ecodian]

The hotel is designed with a centralized aircon system with chiller, cooling tower as the main system, AHU for the lobby, banquet hall and function room while FCU for individual hotel room. The occupancy for the hotel is expected to be highly fluctuated with full occupancy on holiday season but light on low season. What I am interested mainly is on the sizing for the chilled water pipe. If I size the CHWP per the diversity to save cost, will the piping system be unstable when certain floor of the hotel are fully occupied?

[Abby Normal]

On my side of the world we do a lot ov VAV air systems. So with VAV you calculate when the building peaks as well as when the individual zones peak.

You put the equipment in place and the main chilled water pipes, main air ducts etc, to handle what you feel is the buildings peak.

You put the branches from the mains to the zones sized to the zones peak load.

A lot of time residential calculations are an average calculation. The residence is constant volume so identiacal rooms with east and west exposures have the same air flow. They get more air than needed when the sun is not beating on them, and are short a little air when the sun is blaring on them. They are averaged.

So you need to make sure your hotel rooms are not averaged but are counted in the building paeak as if they are vav loads.

Once you get the peak load, based on full occupancy, then you grow some balls and see how full you want to design for for some extra diversity.