Students, faculty, researchers, and engineers from fire safety programs around the world are invited to join a competition to predict the burning behavior of Christmas Trees. The highest individual and highest group scores will be announced to all competition participants.
First place winning team from the 2025 HRR competition are the China Academy of Safety Science and Technology.
Tentatively, this year’s competition is scheduled to take place on Thursday, December 17, 2026, at 12 p.m. (EST). All HRR predictions received prior to this date will be scored for the competition. The invitation to participate will be posted at the top of the page soon.
First and second prize in the 2025 competition (and the winners of the 2025 Golden and Silver pinecones) were earned by the China Academy of Safety Science and Technology and the Technical University of Darmstadt.
Pictured above: Second place winnining team, Technical University of Darmstadt.
In 2025, we received 168 predictions from 55 unique institutions across 22 countries (and 8 US states). Teams of at least 3 individuals from the same University or Research Institution are needed for a chance to win prizes for best team prediction: our coveted golden and silver pinecones.
To be updated in early December, 2026 (after trees are purchased and moved into laboratory storage).
| Ignition |
This year’s ignition source is unique (Fig. 2): a 1.5 m long, 30 cm wide tray with a 6 cm to 10 cm deep layer of excelsior will be placed next to the base of the tree. The tray will be positioned horizontally (flat) and ignited at the far end away from the tree. This does not represent a typical Christmas tree fire ignition scenario but it is relevant to flame spread and burning behavior of trees in wildland fires. Time, t = 0 s is defined as the time when the excelsior is first ignited. Tree ignition time will be defined as the earliest time at which calculated HRR exceeds 50 kW. |
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| Data |
Christmas tree mass loss rate (MLR) will be measured continuously at 1 Hz using a mass balance with a 0.1 g precision. If possible, cone calorimeter measurements will be performed to determine a representative heat of combustion, ΔHc, for each tree. If not, a constant value will be assumed – ΔHc = 17.7 kJ/g [Mell et al. 2009] – and heat release rate will be calculated as: HRR=MLR×∆Hc. |
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New for the 2026 competition: to celebrate & highlight our participants, we invite you to create and share a paper snowflake that has been cut and decorated to represent your institution. All paper snowflakes received by Dec. 10, 2026 will be used to decorate (and burn up with) our competition trees.
Paper snowflake guidelines:
Mail your snowflakes to:
Isaac Leventon
4356 Stadium Drive
Department of Fire Protection Engineering
College Park, MD 20742
United States
Please wait to submit your predictions until trees have been purchased and size/weight information is made available (approx. Dec. 1, 2026).
This year, the submission (and generation of) predicted heat release rate (HRR) curves will once again be made possible by visiting NIST’s Christmas Tree Heat Release Rate (HRR) page. We have updated this year’s curve generator to match expected fire size and allow for greater control over fire growth time. This custom-made app that allows participants to ‘build’ (and submit) a design fire curve by adjusting just four parameters that define:
In this app, after you click ‘Submit by Email,’ an email will be generated that contains the three parameters defining your HRR curve. In this email, please remember to add your name, email address, and lab affiliation if you wish to receive credit (and final competition results) and click send so that we receive your submission.
If you are having trouble automatically generating an email using the ‘Submit by Email’ button, please:
Additionally, a video guide to using this app to create HRR curves and submit predictions is available in Dr. Isaac Leventon’s Youtube Channel.
This year’s experiments will be repeated in triplicate, and your predictions will be scored with respect to the average and uncertainty of repeated results; expanded measurement uncertainties are calculated as per the table below. Points (100 possible) will be awarded in 5 categories as listed below. Our scoring system will award up to 20 points for each category so long as the predicted values are within the calculated uncertainties.
| Description | Uncertainty calculated as: | |
| Peak Heat Release Rate | Propagation of error including uncertainty in (1) time-resolved balance reading, (2) heat of combustion, and (3) standard deviation of repeated measurements | |
| Total Energy Release | Propagation of error including uncertainty in (1) steady-state balance reading, (2) heat of combustion, and (3) standard deviation of repeated measurements | |
| Time to Ignition | Measurement range (upper/lower bounds) | |
| Time to Peak HRR | Measurement range (upper/lower bounds) | |
| Duration for which HRR Exceeds 20% of Peak | Measurement range (upper/lower bounds) | |
Questions? Please contact the fire safety demo leader, Dr. Isaac Leventon (leventon@umd.edu).