We build multi million dollar homes in Phoenix AZ. This is a deseret community and we build slab on grade. 90% of our competitors use underground air returns with rigid duct supply in the attic. We insulate just below the roof, not at the ceiling, so our attic space is a bit more tolerable. We have chosen to install our a/r and supply ducting, flex, in the attic. We would like to understand why our competition uses underground a/r. We have not been able to find anyone in the trade that can show us definitively that one system is better than the other. We strive in everything we do to provide the best products and building techniques for our customers. We are proud of our homes. We do not want to install underground a/r just because most of our competition is doing so. Is there any hard data available showing the pros and cons of each, especially regards the Phoenix AZ area. The idea of returning the air in the cool underground is appealing, but that is not hard data.
Thanks for any help.