Any suggestion about setting old conventional HVAC system (for tall buildings in hot climates)?

(this is in connection with my previous questions here, here and here)

Doing a research project on tall buildings in hot climates (tropical desert e.g. Dubai), I am going to simulate two HVAC systems to represent old and current conditions. The research is not focused on HVAC systems but defining and simulating two hypothetical “conventional” systems are inevitable: one for the past (decades ago, when windows with single pane glass where common) and one for “present” time.

For present scenario I’m using FCU+DOAS…

My question here is about the “past” scenario: Which HVAC systems where most common for tall buildings in the past? Any suggestions about setting related parameters would also be helpful and appreciated e.g. cooling COP, airsideeconomizer, thermostats common values, min and max indoor humidity, etc.


I would recommend putting this question on unmethours as well.

I’ve already asked it there, no replies yet though.

Alright. I have shared your question with one of the engineers with experience in the UAE region. Will post once I hear from him.

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thank you @devang
I’ve just found this document. It’s not about modeling but has good info about the present and future (and in some cases about the past) A/C systems. Worth reading.

Here’s what I got back.

When you say tall buildings, do you mean by High rise buildings?

As I know, since Dubai is relatively new city, most of the buildings are constructed since starting of 2000. There has been very few high rise buildings previously, UAE. One of the older, in fact the first high rise building in middle east is the World trade center (completed in 1979). They had water cooled chillers since the very beginning.

Another example of old building is Hyatt regency Hotel, which was completed in 1980s. They too had water cooled chillers with a capacity of around 5000TR. They too use water cooled chillers.
Most of the residential buildings and office buildings at that time (I presume more than 90%) had Window ACs. These building heights range between 4 to 10 floors.
Hotels built between 80s and 2000 most have air cooled chillers and water cooled chillers. I do know a couple of hotels with window AC too.

The designs are done in UAE, based on design parameters like 115F outdoor temperature and 73.4F (+/- 2) indoor temperature (thermostat set points). They have been following this since very long.
I am not sure about the Efficiencies but it was definitely too low. The current COPs for Air cooled chillers are like 2 to 2.4 COP, Water cooled chillers range between 4.5 to 5.5, DX units would have EER around 8 to 10. Window ACs are now out of the picture.

Economizer use in this region is almost none (still), except few buildings. This is due to the outdoor conditions (dust, stand storm etc.)
The relative humidity indoor ranges between 30% to 60% and the RH outdoor ranges from 0% to 100%.

It is also worth to be noticed that previously (80s and 90s) HVAC systems design was not performed in the right way. They mostly used thumb rules to calculate the capacity of system. This might not be the case with high rise iconic buildings (like WTC and Hyatt).

I believe this should be really helpful.


Thank you and your friend. It’s definitely helpful.

Dear @devang , would you please send me your and your friend’s full names and affiliations as I’d like to mention your contribution in my research documents?