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Community and Q&A

Sizing AC

tomgood46 | Posted in Mechanicals on

We are building a concrete ICF home in a constant hot climate … using ductless a/c … have been told by the ICF people that A/C may not be necessary … I’m not buying this … at least in bedrooms … what size a/c in the bedrooms … will 6000 btu work ? smaller/larger

Thank you

Tom Good

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  1. GBA Editor
    Martin Holladay | | #1

    Air conditioning is not necessary, of course, since people lived for millions of years without it.

    If you want air conditioning, you need to perform a cooling load calculation (otherwise known as a Manual J calculation) to determine the size of your cooling system. Here is more information on performing cooling load calculations: Calculating Cooling Loads.

    Your HVAC contractor is perhaps proposing that the entire cooling load of your house can be handled by just a few ductless minisplit units, without putting an indoor unit in each bedroom. This approach can work, although fewer hot-climate builders have endorsed it than cold-climate builders. For more information on this approach, see Just Two Minisplits Heat and Cool the Whole House.

  2. user-946029 | | #2

    You probably could get away with it, if you take advantage of prevailing winds and extend the overhangs to reduce solar heat gain. Or, an air exchanger would provide a healthy number of ACH.

    Do you have humidity to deal with? If so, a dehumidifier would help give you comfort.

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