open door cooling load 2

[javier83]

Hi!
I am running a cooling load test at a lifestyle shopping center. In these centers, tenants operate with their doors open and therefore cold air leaves the room and the warm air from outside enters (during the cooling season). I would like to know how to calculate this extra load to show the tenants how much power they need if they want to operate with open doors.

I have followed ASHRAE funtamentals when calculating the cooling load, but they do not address the open door situation. I would like to know how to calculate this and what are the variables I need (pressure differential, temperature differential, wind speed and direction).

Thank you

 

[marcoh]

All the variables you mentioned have a large impact on the infiltration load into the tenancy and are all very hard (if not impossible) to quantify into hard $$!

If the tenant has 2 doors (front and back say), a 1m/s wind can easily produce 4m3 of infiltration which the AC will never be able to handle.

Wost case scenario is that the AC system runs at 100% capacity when ambient is above room conditions. Best case scenario is assuming infiltration as per normal energy modelling calcs and reality will be somewhere between the two.

 

[quark]

Good point by Marcoh.

Dehumidification handbook by Munters suggest the calculations to be based upon 150fpm velocity across the door and applying ambient conditions to indoor conditions for calculating sensible and latent loads. Try to get near exact values of no. of door openings and the duration of door opening. The main redundancy comes when we assume full door opening from the time you push it and till it closes completely.

If it is an already existing store, take some readings and get an average figure.