Hot smoke tests with Izar

Ever-larger and more complex building requirements entail increased requirements for smoke extraction in order to ensure personal safety in the event of a fire. In many cases, computer-based smoke exhaust simulations are carried out to demonstrate an adequate low-smoke layer during evacuation. Simulations rely on assumptions and simplified building geometries.
For quality assurance and verification of the correct dimensioning, a practical demonstration can be helpful. Basler & Hofmann therefore offers hot smoke testing on site, in addition to our computational models. The company has developed the innovative Izar test system, which puts the smoke exhaust system to the test. The specially designed gas burner burns the gas mix completely – enabling a maximum heat generation without any residue. The system is patented in Switzerland as well as in Europe.


  • Evidence of the low-smoke layer during the evacuation phase for rooms with high occupancy, with and without smoke extraction
  • Quantitative proof of the effectiveness and correct dimensioning of smoke extraction systems in buildings, underground garages, tunnels, etc.
  • Monitoring the spread of smoke in structures in which smoke is not extracted (such as railway tunnels)
  • Experimental assessment of the basic requirements for buildings with complex geometry
  • Quality assurance for engineered designs

Testing procedure

Izar is a mobile system and can be set up and used very rapidly. Special burners enable reproduction of any fire curve with high heat release rates in the megawatt range. Optimised combustion at stoichiometric balance enables the system to meet or undercut legal environmental thresholds and prevents damage to the building through soot formation or high flames. In order to visualise the heat transfer, a heat-resistant and precipitate-free fog fluid is fed in above the “fire source”. Sensors installed in the room record the temperature distribution. The data enable a detailed evaluation of the test, as well as comparisons with the computational model.

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Related areas of expertise

Fire protection , Tunnels , Structural engineering , Risk analysis and safety management , Building services