Housing Ventilation Room Volume Factor Tool

Description

Return netVolume = floorArea*ceilingHeight-displacedVolume, airChangesPerHour = airflowPerHour/netVolume and nominalResidenceHours = netVolume/airflowPerHour.

Air-change and transfer calculations relate a volume, flow, time and driving force under an assumed model. Nominal air exchange or a well-mixed exponential response differs from measured clearance, spatial mixing and contaminant-specific treatment.

Return netVolume = floorArea*ceilingHeight-displacedVolume, airChangesPerHour = airflowPerHour/netVolume and nominalResidenceHours = netVolume/airflowPerHour.

When to use this tool

Use Housing Ventilation Room Volume Factor when checking a supplied ventilation, concentration-decay or oxygen-transfer term.

How to use the tool and how it works

Enter floorArea, ceilingHeight, displacedVolume, airflowPerHour. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read netVolume, airChangesPerHour, nominalResidenceHours. Use the output convention below.

Require positive floorArea, ceilingHeight and airflowPerHour and nonnegative displacedVolume smaller than floorArea*ceilingHeight. Return netVolume = floorArea*ceilingHeight-displacedVolume, airChangesPerHour = airflowPerHour/netVolume and nominalResidenceHours = netVolume/airflowPerHour. Volume and hourly airflow must use the same volume unit.^[1]

Input field	Meaning and units	Accepted input
floorArea	Floor Area	Required. Finite number; strictly above 0.
ceilingHeight	Ceiling Height	Required. Finite number; strictly above 0.
displacedVolume	Displaced Volume	Required. Finite number; minimum 0.
airflowPerHour	Airflow Per Hour	Required. Finite number; strictly above 0.

Output field	Interpretation	Returned shape
netVolume	Net Volume	Required. Finite number.
airChangesPerHour	Air Changes Per Hour	Required. Finite number.
nominalResidenceHours	Nominal Residence Hours	Required. Finite number.

json

{
  "input": {
    "floorArea": 20,
    "ceilingHeight": 3,
    "displacedVolume": 10,
    "airflowPerHour": 100
  },
  "output": {
    "netVolume": 50,
    "airChangesPerHour": 2,
    "nominalResidenceHours": 0.5
  }
}

Limitations and assumptions

The residence time is a nominal mixed-volume ratio, not guaranteed clearance time or evidence of adequate ventilation. Supply effective relevant airflow rather than assuming all recirculated air removes contaminants.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use measured effective airflow and a suitable mixing or transport model before drawing conclusions about treatment performance or exposure.

References

Calculation and input contract: environmental-health/housing-ventilation-room-volume-factor — tool.io

Similar or alternative tools

Indoor Air Change Exponential Removal Term
Compute remainingFraction = exp(-airChangesPerHour*hours) and finalConcentration = equilibrium+(initial-equilibrium)*remainingFraction.
Household Water Filter Throughput Factor Tool
Calculate household water filter throughput factor from explicit caller-supplied inputs.