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I figured out at least part of my problem. When I changed my simplified model from one with a Packaged Rooftop VAV with Reheat to one with Ideal Air Loads, I forgot to change my zone cooling and heating design airflow method to DesignDay. I had previously set it to Flow/Zone. I still do not know why the user design heating load was so high though, nor why the user design airflow was so low by comparison.

Now my user design heating load is showing up as 18,440 BTUH (which is about 10% higher than the answer I get by multiplying the BTUH/SF by the zone floor area.). Seems reasonable.

The user design airflow is still coming out low by comparison. If my design heating supply air temperature is 105 degrees F and I'm trying to maintain 70 degrees F setpoint on my heating design day, the associated zone airflow in heating for a user design heating load of 18,440 BTUH should be around 488 cfm. The zone report now gives only 8.12 cfm as user design airflow in heating.

I figured out at least part of my problem. When I changed my simplified model from one with a Packaged Rooftop VAV with Reheat to one with Ideal Air Loads, I forgot to change my zone cooling and heating design airflow method to DesignDay. I had previously set it to Flow/Zone. I still do not know why the user design heating load was so high though, nor why the user design airflow was so low by comparison.

Now my user design heating load is showing up as 18,440 BTUH (which is about 10% higher than the answer I get by multiplying the BTUH/SF by the zone floor area.). Seems reasonable.

The user design airflow is still coming out low by comparison. If my design heating supply air temperature is 105 degrees F and I'm trying to maintain 70 degrees F setpoint on my heating design day, the associated zone airflow in heating for a user design heating load of 18,440 BTUH should be around 488 cfm. The zone report now gives only 8.12 cfm as user design airflow in heating. heating, which is too low.