izXfer

Name Type Variability Description/Comments
zi1 TI Start of run subscripts of zones involved (air flow > 0 = into zone 1)
zi2 TI Start of run iz_zi2 = -1 iff not interzone
doas TI Start of run subscript of DOAS where air is supplied from (air flow > 0), or exhausting to (airflow < 0)
ua UA Start of hour air-to-air coupling const (Btuh/F) thru walls etc.
nvcntrl choice:IZNVTY input time
  • Control type for nat vents:
  • C_IZNVTYCH_NONE: no venting (iz_ua only)
  • C_IZNVTYCH_ONEWAY: "diode" variant of 2 way (xfer iff t1 > t2)
  • C_IZNVTYCH_TWOWAY: high/low/hdiff vent (pre-2010)
  • C_IZNVTYCH_ANEXT: airnet vent to exterior (zi2=-1)
  • C_IZNVTYCH_ANIZ: airnet vent between zones
  • C_IZNVTYCH_ANHORIZ: airnet large horiz opening (e.g. stairwell)
  • C_IZNVTYCH_ANEXTFAN: airnet fan to/from exterior (zi2=-1)
  • C_IZNVTYCH_ANIZFAN: airnet fan between zones
  • fan flow adds fan heat / uses electricity
  • C_IZNVTYCH_ANEXTFLOW: airnet specified flow to/from exterior (zi2=-1)
  • C_IZNVTYCH_ANIZFLOW: airnet specified flow between zones
  • specified flow transfers air (no fan heat, no elec)
  • C_IZNVTYCH_ANHERV: heat/energy recovery ventilator
  • C_IZNVTYCH_ANDUCTLK: duct leakage
  • C_IZNVTYCH_ANSYSAIR: system air flow
  • C_IZNVTYCH_ANOAVRLF: [RSYS][rsys] OAV relief air
  • ( = interzone hole sized per flow)
afCatI AFCAT Start of run
  • air flow input category (accounting only) C_AFCAT_xxx
  • or 0 = unknown
  • resolved to iz_afMtrCat1 and iz_afMtrCat2 for runtime
  • AFMTR pointers, derived from zone zn_afMtri
  • NULL if not specified or same on both sides of IZ type
Name Type Variability Description/Comments
afMtrCat1 number Start of run ... for iz_pAfMtr1
afMtrCat2 number Start of run ... for iz_pAfMtr2
Name Type Variability Description/Comments
a1 AREA_GEZ Start of hour
  • vent area 1, ft2
  • _TWOWAY = low vent area
  • AirNet = minimum vent area ("infil only")
a2 AREA_GEZ Start of hour
  • vent area 2, ft2
  • _TWOWAY = high vent area
  • AirNet = maximum vent area ("infil + vent")
  • BUT note it is OK if a1 > a2
L1 LEN_GZ input time opening dim 1, ft (_ANHORIZ)
L2 LEN_GZ input time opening dim 2, ft
hz number input time
  • _AN (non FAN): height of iz_a1 relative to arbitrary 0 (ft)
  • _TWOWAY: height a1 - height a2 difference (ft)
Name Type Variability Description/Comments
stairAngle FLOAT_GEZ input time
  • stair angle, deg (_ANHORIZ) (90 = vert)
  • default = 34 deg
cd FRAC_GZ input time orifice coefficient, dimless (user input, default 0.8)
exp number Start of run power law exponent, (user input, default 0.5)
cpr number input time wind pressure coefficient (ignored if not _ANEXT)

fan volume flow (cfm, += into zone1; if <0, fan is exhaust)

Name Type Variability Description/Comments
vfMin AFLOW Start of subhour
  • min vent flow rate, cfm (for fixed flow types)
  • (*net* supply flow for _ANHERV)
vfMax AFLOW Start of subhour max vent flow rate, cfm (for fixed flow types)
tEx TEMP Start of subhour
  • vent exterior air drybulb temp for ANEXT, ANEXTFAN, ANEXTFLOW, and ANEXTHERV, F
  • default = current ambient dry bulb (from weather file)
wEx FRAC_GZ Start of subhour
  • vent exterior air humidity ratio, lb/lb
  • default = current ambient humidity ratio (from weather file)
windSpeed FLOAT_GEZ Start of subhour
  • windspeed seen by this vent, mph
  • default = zone-adjusted windspeed
linkedFlowMult FLOAT_GZ input time
  • multiplier for flow to/from linked zone or [DOAS][doas] or ...
  • applied to flow seen by "other" zone or device (but not this zone)
  • supports zone multiplier schemes
  • initially implemented for [DOAS][doas] only, 6-1-2023
Name Type Variability Description/Comments
ASEF number Start of subhour apparent sensible effectiveness (for _ANHERV)
LEF number Start of subhour latent effectiveness (for _ANHERV)
SRE number Start of subhour HVI sensible recovery efficiency (for _ANHERV)
ASRE number Start of subhour HVI adjusted sensible recovery efficiency (for _ANHERV)
RVFanHeatF number Start of subhour
  • fraction of HERV fan power that heats supply air (experimental)
  • default 0
vfExhRat number Start of subhour
  • exhaust ratio (for _ANHERV) = (vfGross exhaust)/(vfGross supply)
  • default = 1 (balanced)
EATR number Start of subhour
  • exhaust air transfer ratio (for _ANHERV)
  • vfGross = vfNet / (1.-EATR)
fan vent fan characteristics (unused if not fan type)
FAN
Name Type Variability Description/Comments
fan.fanTy choice:FANTY Start of phase
  • fan position choice, according to application as follows; constant.
  • air handler supply: DRAWTHRU (default) or BLOWTHRU
  • ah return/relief: NONE (default), RETURN, or RELIEF
  • terminal: NONE (default), SERIES, or PARALLEL
  • zone exhaust fan: NONE or EXHAUST (no types, just whether exists)
  • AirNet ([IZXFER][izxfer]): ditto
fan.vfDs AFLOW_GZ End of subhour design volumetric flow (cfm actual air). constant, RQD except as noted. *s cuz varies when autoSizing.
fan.vfDs_As AFLOW Start of phase autoSized ditto for ah sfan and rfan for naming consistency. 6-95.
fan.vfDs_AsNov AFLOW Start of phase
  • raw autoSized ditto b4 overSize added, for report/probes. 7-95.
  • cnausz.cpp code ASSUMES x, x_As, x_AsNov together for access thru one ptr. cuprobe.cpp's name search also requires together.
fan.vfMxF number Start of phase
  • factor by which fan flow will exceed vfDs (at reduced pressure). default 1.3. constant.
  • Error if < 1.0; typically <= 1.5.
Name Type Variability Description/Comments
fan.press PRESAIR_GEZ Start of run
  • system design pressure, "H2O (inches of water), constant, used in defaulting power / efficiency.
  • default: supply 3, r/r .75, tu .3, zx ???.
  • 0 allowed 5-1-92 to eliminate fan heat for test/calibration purposes.
only one of eff and shaftPwr may be given:
Name Type Variability Description/Comments
fan.eff FRAC_GZ Start of run
  • fan (hydraulic) efficiency at vfDs and press (any temp), constant,
  • default from power if given, else .65. (1-eff) of fan shaft power is converted to heat in airstream.
fan.shaftPwr BHP_GZ Start of run
  • fan shaft power at vfDs and press (any temp). constant. default: from eff
  • Btuh internally, entered in BHP (user name 'shaftBhp') (cvpak converts).
  • ^^^^make user name 'shaftBhp'. field type name??
fan.elecPwr FLOAT_GZ Start of run
  • motor input power, W/cfm (based on vfDs); shaftPwr and elecPwr cannot both be
  • input
Name Type Variability Description/Comments
fan.motTy choice:MOTTY Start of run
  • motor type (C_MOTTYCH_PSC or C_MOTTYCH_BPM)
  • [RSYS][rsys] only minimal use 4-12, could effect defaults
Name Type Variability Description/Comments
fan.motEff FRAC_GZ Start of phase motor/drive efficiency, constant, default .9.
Name Type Variability Description/Comments
fan.motPos choice:MOTPOS Start of phase
  • motor/drive position: choice of INFLO (default), INRETURN, EXTERNAL. constant.
  • INRETURN is for supply fans only and will be deferred/omitted if difficult
  • chip per taylor 3-4-92).
Name Type Variability Description/Comments
fan.curvePy fan part-load energy consumption curve cubic polynomial coefficients with x0
PYCUBIC2
Name Type Variability Description/Comments
fan.curvePy.k[index] number Array [6] Start of phase FLOAT k[6]. [0..3] are coeff, [4] is minimum x, [5] is terminator needed by cul.cpp.
Name Type Variability Description/Comments
fan.mtri TI input time subscript of meter (MTR) to which energy consumption is charged
fan.endUse choice:ENDUSE Start of phase
  • end use to which energy consumption is charged
  • not used for all fans (many implicitly default to "fan")
Name Type Variability Description/Comments
fan.ausz BOO Start of run
  • non-0 if fan being autoSized (AH sfan, rfan): input contained [AUTOSIZE][autosize] _fanVfDs. 7-1-95.
  • see also AH::fanAs, asRfan, asFlow. 7-1-95. */
  • FAN setup time members, set by cnfan.cpp:FAN::setup. May be resetup during autoSize run.
  • also cMx may be init by setup, to be non-0.
Name Type Variability Description/Comments
fan.outPower number Start of subhour
  • motor output power (work done by fan), member 7-95 for one setup check in cncult5.cpp
  • inPower = shaftPwr/motEff is computed as needed.
fan.airPower number Start of subhour
  • fan heat to air (Btuh) at vfDs (& pressure): work done by fan, plus motor/drive inefficiency if in flow.
  • Note work done by fan is modelled as HEAT ADDED TO AIR AT FAN per Chip/Niles (3-92, undocumented)
  • heat to air around motor (in return air etc) at design flow is: (inPower - airPower). this is 0 if motor in air flow.
FAN runtime members, set by cnah.cpp:FAN::pute( cFlow, temp)
Name Type Variability Description/Comments
fan.cMx CFLOW End of subhour max heat cap flow (Btuh/F) at curr air temp & run press & ref w: .vfMx * air vsh * 60 (min/hr)
fan.c CFLOW End of subhour current average flow in heat cap units (Btuh/F): input saved for probing by last call to FAN::pute()
fan.t TEMP End of subhour current air temp, input saved ditto, used in converting BtuF/F to cfm
fan.frOn number End of subhour
  • fraction of time fan is on, saved input
  • made local to pute()to save members 10-92:
  • *s *e FRAC relFlow // fraction of design flow
  • *s *e FRAC relLoad // fraction of full load per part load curve for fan type (1.0 if over design flow: assume pressure drops)
fan.p number End of subhour (motor) power consumption for subhour -- inPower * relLoad. *subhrDur for meter.
fan.q number End of subhour heat (power) to air this subhour: airPower * relLoad. Member needed in addition to c and dT??
fan.dT TEMPDIFF End of subhour temp difference due to fan: q/c
fan.qAround number End of subhour heat to air around motor, if not in air flow, for use re supply fan motor in return air

derived / internal

Name Type Variability Description/Comments
nvcoeff number Start of run nat vent overall coeff Btuh/(dt^.5). set by izxSetup().
air1 z1 air state (tdb and w)
AIRSTATE
Name Type Variability Description/Comments
air1.tdb DBL End of subhour air dry-bulb temp, F
air1.w DBL End of subhour air humidity ratio, lb moisture/lb dry air
air2 z2 air state (may be ambient or from DOAS)
AIRSTATE
Name Type Variability Description/Comments
air2.tdb DBL End of subhour air dry-bulb temp, F
air2.w DBL End of subhour air humidity ratio, lb moisture/lb dry air
Name Type Variability Description/Comments
rho1 number Start of subhour z1 moist air density, lb/cf
rho2 number Start of subhour z2 moist air density, lb/cf (may be ambient or from DOAS)
ad[index] Array [2]
  • airnet working data
  • [ 0]: infil only
  • [ 1]: infil+vent
ANDAT
Name Type Variability Description/Comments
ad[index].Ae AREA_GEZ End of subhour effective vent area, ft2; function of vent type and iz_cd
ad[index].AeLin AREA_GEZ End of subhour modified iz_Ae, ft2; prevents discontinuity at delPLinear
ad[index].pres1 DBL End of subhour pressure at z1 side of element, lbf/sf (for pressure-dependent)
ad[index].pres2 DBL End of subhour pressure at z2 side of element, lbf/sf (for pressure-dependent)
ad[index].delP DBL End of subhour pressure diff across element, lbf/sf (+ = pz1 > pz2)
ad[index].mdotP DBL End of subhour
  • air mass flow rate, (lbm moist air)/sec (+ into z1)
  • pressure driven: derived via pressure balance
  • fixed flow: as set
ad[index].dmdp DBL End of subhour derivative of ad_mdotP wrt pressure (0 for fix flow)
ad[index].mdotB DBL End of subhour
  • add'l buoyancy-driven mass flow, (lbm moist air)/sec
  • balanced flow z1 <-> z2, used only for _ANHORIZ
ad[index].mdotX DBL End of subhour
  • air mass exhaust flow, (lbm moist air)/sec (+ out of z2)
  • HERV = exhaust flow
  • Other = ad_mdotP
ad[index].xDelpF DBL End of subhour buoyancy flooding pressure factor
ad[index].xMbm DBL End of subhour buoyancy max possible flow factor
ad[index].tdFan DBL End of subhour air stream temp rise across fan, F
ad[index].pFan DBL End of subhour fan (electrical) power for meter, Btuh (*not* W)
amfNom number End of subhour
  • nominal air mass flow, lbm/sec
  • = fVent weighted average of iz_ad[ 0] and iz_ad[ 1]
  • NOTE: approximate when fVent not 0 or 1