EXCEL

[fouttyw]

Does anyone have an excel spreadsheet that I can put in BTUs/and cubic feet of a room and it will tell me the AC size I need.

 

[ChrisConley]

No. Such a program doesn't really exist.

You need to add windows (type and orientation), walls, roof, floor, interal gains: people, lights, equipment.

Try searching for 'load estimating software'. There are some less expensive software packages out there.

Try:

http://www.elitesoft.com/

 

[MintJulep]

If you know the BTU's, you know the size AC you need.

 

[stanlsimon]

Twenty years ago we did hand load calculations using the method prescribed in the ASHRAE manual. That avenue is still open. You need to figure all the surface areas of wall, window, roof,and floor along with their respective U values and solar heat gain factors. A spread sheet program would make the process somewhat less laborious.

You also need to know how many people, how much lighting, any miscellaneous heat loads such as cooking, computers, motors, etc.

Don't forget to add in heat or cooling of required outside ventilation air as well as unwanted infiltration.

It is much easier to use computer software such as Carrier E-20.