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Community and Q&A

Calculating Conditioned Floor Area

Alan Ferguson | Posted in Energy Efficiency and Durability on

I’m calculating the conditioned floor area to determine ventilation needs for my new construction home. Is the floor of an open loft included?

My home is a 26 x 48 timberframe on a slab. Half of the ground floor–26 x 24–is an open “great room” with kitchen, dining, and living space. Above the kitchen is a 13 x 12 loft open to the “great room.” Is the area of the loft included in the total conditioned floor area?

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  1. Steve Knapp CZ 3A Georgia | | #1


    I'll give your post a bump. My layman's understanding of the ASHRAE ventilation guidelines is they are more of a ballpark than a precise formula for calculating rates. That is, I don't think the loft really matters. But let's see if one of the experts will chime in.

  2. Jon R | | #2

    Agreed, I'd focus more on using low VOC materials, good/comfortable/safe kitchen exhaust and assuring 15+ CFM/person to all long term occupied, closed door rooms (eg, bedrooms, office).

  3. Alan Ferguson | | #3

    Steve/Jon, thanks for your thoughts. Decided not to include the loft area. Should someone with more knowledge on the subject see this, I'd love to learn more.

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