Calculated Results
Example Data Table
Sample inventory and energy values for a small storage room.
| Material | Mass (kg) | Heat of combustion (MJ/kg) | Energy (MJ) |
|---|---|---|---|
| Cardboard | 180 | 16.5 | 2970 |
| Mixed plastic | 70 | 30.0 | 2100 |
| Wood pallets | 120 | 18.0 | 2160 |
| Total | 7230 |
Formula Used
Total fire load energy: Q = Σ(mᵢ × Hᵢ)
Fire load density: q = Q / A where A is floor area.
Adjusted density (optional): qₐ = q × SF where SF is the safety factor.
Wood-equivalent loading: w = qₐ / Hwood with Hwood in MJ/kg.
How to Use This Calculator
- Enter the compartment floor area in square meters.
- Add each combustible material as a separate row.
- Provide mass and a suitable heat of combustion value.
- Apply a safety factor when data quality is uncertain.
- Press Submit to display results above the form.
- Download CSV or PDF for reporting and archiving.
Inventory quality and uncertainty
Fire load results depend on how completely materials are listed. Missing packaging, pallets, and mixed plastics can shift totals by hundreds of megajoules in typical storerooms. Use weigh tickets, purchase records, and spot checks to improve mass estimates. When uncertainty is high, apply a safety factor so the adjusted density reflects conservative planning.
Heat of combustion selection
Heats of combustion vary by product grade and moisture. Paper products often fall near 14–16 MJ/kg, timber near 18 MJ/kg, and mixed polymers commonly exceed 25 MJ/kg. If multiple material types exist in one pile, treat them as separate rows. This calculator multiplies mass and heat value per item to build the total energy.
Density interpretation for compartments
Fire load density expresses megajoules per square meter of floor area. For a 60 m² room, adding 7,230 MJ produces about 121 MJ/m², and a 1.10 safety factor increases it to about 133 MJ/m². Density supports comparisons between spaces, helps prioritize housekeeping, and informs engineering discussions about protection levels.
Material breakdown insights
The Plotly chart highlights which materials dominate the energy budget. A small mass of plastics can contribute more energy than larger masses of paper or wood. Use the breakdown to target controls: reduce polymer stock, separate ignition sources, and improve segregation. Exported reports preserve the breakdown for audits and change tracking.
Wood-equivalent reporting
Wood-equivalent loading converts adjusted density to an equivalent kilograms of wood per square meter using a reference energy value, commonly 18 MJ/kg. This is helpful when communicating with non-specialists. If your reference differs, update the wood energy input and the conversion will update immediately in the results panel.
Workflow for periodic reassessment
Operational inventories change, so reassess fire load on a schedule or after storage reconfigurations. Capture baseline results, then repeat quarterly for high-turnover areas. Compare adjusted density and the top three contributors over time. When trends rise, revise storage limits and housekeeping rules to keep risk within acceptable targets.
Input units and consistency checks
Keep units consistent: mass in kilograms, heat values in MJ/kg, and area in square meters. If results look extreme, verify decimal placement and inclusion boxes. A quick reasonableness check is energy per pallet. Small corrections can change density in compact rooms.
FAQs
What is fire load in practical terms?
Fire load is the total potential heat energy from combustible contents in a space. It is computed from material mass and heat of combustion, then summarized as energy and energy per floor area.
Which area should I use for density calculations?
Use the effective compartment floor area where the combustible contents are stored. If the space has separated rooms, calculate each room separately to avoid diluting density with unused area.
How do I choose heat of combustion values?
Prefer manufacturer data, test reports, or reliable references for similar products. If only broad categories are available, keep items separate and apply a safety factor to cover variability and uncertainty.
Why does the chart show large impact from plastics?
Many plastics have high energy content per kilogram, often higher than wood or paper. Even modest plastic mass can dominate the total energy and drive the adjusted density upward.
Does the safety factor change the total energy?
The safety factor does not change the physical inventory energy sum. It scales the density for conservative reporting and decision-making, reflecting uncertainty in masses, heat values, and inventory completeness.
Can I use this output for code compliance directly?
Use it as an estimate and documentation aid. Formal compliance depends on the applicable local requirements and professional assessment of occupancy, compartmentation, and protection systems.