Hi Charles,

If all materials in your layers use the simplified resistance entry
format, there is no mass associated with the wall. When using the layer
methodology, you must use the "properties" format for the majority of
your materials. The properties format includes specific heat and
density input values. The layer constructions require specific heat and
densities in order to take thermal mass into account in the load and
energy balance calculations. If you do not want the thermal mass taken
into account, you can use a simplified construction and specify a user
defined U-value. Keep in mind that Appendix G requires thermal mass
calculations to be done for both the Proposed and Baseline buildings.
Simplified constructions should only be used during very early schematic
design runs for quick snapshots.

Regards,

Sheila Sagerer