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check zone sizing values #622

Open mdahlhausen opened 5 years ago

mdahlhausen commented 5 years ago

The .idd sizing zone heating maximum airflow fraction is default to 0.3 assuming a VAV system Check HVAC system types and make sure this is set to 1.0 for DOAS and non-VAV systems. Likely a source of heating unmet hours in some models.

jiangithub commented 5 years ago

DesignDay method should be used for the following two inputs under sizing:zone. Then, the heating maximum airflow fraction input should not affect the simulation. !- Heating Design Air Flow Method !- Cooling Design Air Flow Method

For zones served by AirTerminal:SingleDuct:VAV:Reheat, the following input should be used to inform sizing and to align with E+ prototypes. 0.5, !- Maximum Flow Fraction During Reheat From test runs to create the six DOE prototypes with multiple zone VAV systems, I saw four of them use 0.5 already but medium office and primary school use Autocalculate. Both of them should be changed to 0.5. It is known that E+ will ignore the input of 0.5 for reheat coil type other than hot-water coil, i.e. the input doesn't impact medium office with electric reheat.

EnegyPlus V9.0 I/O Reference: For heating coil types other than the hot-water coil, e.g. electric, steam, and gas, the reverse action works the same as the normal action always keeping the air flow at the minimum during heating.

It is not clear why air_terminal_single_duct_vav_reheat_set_heating_cap is needed instead of using the autosize feature in E+.