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Calcimator

Fire Origin & HRR Calculator

Estimate heat release rate, flashover time, and ventilation control for fire investigation. Uses Thomas correlations and t-squared growth models.

Inputs

sq ft
ft
lbs/sq ft
sq ft

Results

Heat Release Rate

3,254 kW

≈ 217 homes' peak draw

Time to Flashover

2.9 min

Ventilation ControlledYes
How to Use This Calculator
  1. Enter Room Area, Ceiling Height, and Fuel Load.
  2. Set Ventilation Opening.
  3. Review Heat Release Rate (kW) and Time to Flashover (min).
  4. Use Ventilation Controlled to inform your decision.
  5. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Ventilation Opening

Ventilation OpeningHeat Release RateTime to Flashover
111,541 kW2.4 min
366,784 kW3.7 min
6510,280 kW5 min
9010,280 kW6 min

What each input means

Room Area
Floor area of the room of origin.
Ceiling Height
Floor-to-ceiling height of the room.
Fuel Load
Combustible material weight per square foot (residential avg: 5-10).
Ventilation Opening
Total area of windows and doors open during the fire.

What each result means

Heat Release Rate
Estimated peak HRR based on controlling factor.
Time to Flashover
Estimated time from ignition to flashover.
Ventilation Controlled
Whether the fire was limited by available air supply.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Room Area = 200, Ceiling Height = 8, Fuel Load = 8, Ventilation Opening = 20 = 4 input(s) provided
  2. Calculate Heat Release Rate
    Heat Release Rate
    3254 = 3254
  3. Calculate Time to Flashover
    Time to Flashover
    2.9 = 2.9
  4. Calculate Ventilation Controlled
    Yes = Yes

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