Bugfix for CFIS systems w/ supplemental fan and sub-hourly timesteps

[shorowit]

Pull Request Description

Discovered a bug with supplemental fan runtime for a CFIS system when using sub-hourly timesteps. It would be awfully complicated to fix the issue given how the CFIS EMS program operates (based on time), so I rewrote the program to be simpler (based on outdoor cfm). Now simulations with sub-hourly timesteps better match simulations with hourly timesteps. CFIS systems run with hourly timesteps or without supplemental fans are unchanged.

	60 min timestep (MBtu)	15 min timestep, orig (MBtu)	15 min timestep, now (MBtu)	15 min timestep, orig (Diff)	15 min timestep, now (Diff)
base-mechvent-cfis.xml	63.6	63.9	63.9	0.6%	0.6%
base-mechvent-cfis-airflow-fraction-zero.xml	63.6	63.9	63.9	0.6%	0.6%
base-mechvent-cfis-control-type-timer.xml	63.9	64.2	64.2	0.5%	0.5%
base-mechvent-cfis-dse.xml	63.6	63.9	63.9	0.6%	0.6%
base-mechvent-cfis-evap-cooler-only-ducted.xml	33.5	33.6	33.6	0.0%	0.0%
base-mechvent-cfis-no-additional-runtime.xml	53.9	54.5	54.5	1.2%	1.2%
base-mechvent-cfis-no-outdoor-air-control.xml	64.4	64.9	64.9	0.8%	0.8%
base-mechvent-cfis-supplemental-fan-exhaust-synchronized.xml	60.3	59.1	60.8	-1.9%	0.8%
base-mechvent-cfis-supplemental-fan-exhaust.xml	59.3	58.5	59.8	-1.4%	0.8%
base-mechvent-cfis-supplemental-fan-supply.xml	62.8	59.8	63.1	-4.8%	0.5%

Note 1: We don't expect perfect agreement but HVAC runtime fractions will differ a small amount between hourly and sub-hourly simulations.

Note 2: All files were run with zero infiltration, zero duct losses, and an unvented clothes dryer to eliminate interactions.

Checklist

Not all may apply:

• Schematron validator (EPvalidator.xml) has been updated
• Sample files have been added/updated (openstudio tasks.rb update_hpxmls)
• Tests have been added/updated (e.g., HPXMLtoOpenStudio/tests/test*.rb and/or workflow/tests/test*.rb)
• Documentation has been updated
• Changelog has been updated
• openstudio tasks.rb update_measures has been run
• No unexpected changes to simulation results of sample files