Verif.2.6: Occupant incapacitation

1. Definition

One occupant stands in the centre of a room of 10 m by 10 m by 3 m with no fire. A pre-evacuation time above 10,000,000 s keeps the occupant in place. Hazardous conditions, such as CO, HCN, CO2, irritants, heat or radiation, are applied according to the incapacitation sub-model of the evacuation model. The time at which the model’s Fractional Effective Dose (FED) reaches 1 is compared with the same time from a hand calculation or an independent fire model that uses the same FED equations at the occupant’s position. The test is a modified version of a test of Korhonen and Hostikka (2009).

Source: NIST TN 1822, Verif.2.6, pp. 23-24, Fig. 2. This is a paraphrase, not the text of the standard.

Reference: Ronchi, E., Kuligowski, E. D., Reneke, P. A., Peacock, R. D., Nilsson, D. (2013). The Process of Verification and Validation of Building Fire Evacuation Models. NIST Technical Note 1822. National Institute of Standards and Technology. 10.6028/NIST.TN.1822 (Page numbers are the printed page numbers of TN 1822.)

2. Scenario

Scenario picture not available.

3. What to expect

The time to FED = 1 in the evacuation model equals the time in the hand calculation or fire model. The result is a quantitative comparison of the two times. TN 1822 asks to repeat the test for each hazardous condition of the sub-model, and states that a model without a toxicity or hazard sub-model should describe that limitation. The test is static, and testers may extend it to a moving occupant.

Our criterion: Timestep-integrated FDS+Evac FED reaches 1 within one timestep of the independent constant-hazard calculation

FED is accumulated by a test-local adapter on each timestep (JuPedSim has no native FED model); the test checks the adapter against a hand calculation.

4. Our result

Status: TEST-LOCAL

Test cases of this row

• test_time_to_fed_one: bound: expected <= measured <= expected + dt, expected = 1 / closed-form FED rate (dt = 0.05 s, deterministic run)

5. Our implementation

Deviations from the standard:

• JuPedSim has no hazard, FED or incapacitation model. A test-side adapter integrates the FDS+Evac FED (Korhonen and Hostikka 2009) on every time step (dt = 0.05 s) for constant CO = 5000 ppm, CO2 = 2 % and O2 = 18 %: the CO dose rate 4.607e-7 C^1.036 per second (C in ppm), multiplied by the CO2 factor exp(0.1930 c + 2.0004) / 7.1 (c in %), plus the low-O2 rate 1 / (60 exp(8.13 - 0.54 (20.9 - O2))) per second. When FED reaches 1 the adapter sets the desired speed to zero. This gives FED = 1 after about 208 s.
• What is verified: the time integration of the adapter, that is, the step on which the sum crosses 1 is the first step at or after the closed-form time 1 / (total rate) and at most one time step later, and the occupant stays at its position. What is not verified: the FED model against an independent source (the reference uses the same equations), JuPedSim itself, or any hazard in a spatially or temporally varying field.
• Only the combined CO, CO2 and O2 condition is run. TN 1822 asks for each hazardous condition separately, and other hazards (HCN, heat, irritants) are not implemented.
• The occupant is held at (5, 5) m by a waiting stage that never ends. This is the same as a pre-evacuation time above 10,000,000 s without running that long. The room is two-dimensional, so its 3 m height is not represented.
• The scenario is built in code (tests/vv/test_nist.py) rather than loaded from a scenario file.

Model: CollisionFreeSpeedModel

• Test function: tests/vv/test_nist.py::test_time_to_fed_one

6. Our notebook

No notebook for this test yet.