Possible master- and graduation projects
Physiological aspects in personal safety
What is the resistance of building occupants to heat flux, convective heat and toxicity of smoke gases? Is it possible to define the resistance of the human body in a mean value with a standard deviation, for several categories of age, heath level and damage levels (1st degree, 2nd degree, lethality)? Not only the human skin, but also the respiration system is relevant in relation to this research question.
Fire resilience: probabilistic building life time due to fire events
In most building codes personal safety of building occupants is the main objective. Because in most building codes an evacuation concept is applied in case of fire, a burn down scenario is acceptable, as long as there is enough time for building occupants to evacuate the building. Apparently, fire resilience is not one of the fire safety objectives in the building code. The risk subsystems ‘fire and smoke resistance of compartmentwalls’ and ‘fire resistance of load bearing structure’ are so called Lines of Defence, they don’t have to be extremely reliable.
Both separation constructions and load bearing elements can be assumed to be fire safe, when the required safe time (RST: the thermal load by a natural fire, expressed in minutes Standard Fire Curve) doesn’t exceed the available safe time (AST: the fire resistance of the construction in minutes Standard Fire Curve). In the comparison AST > RST time don’t apply to real time, but applies to a thermal energy according tot he standard fire curve. The larger the interval is between AST and RST, the higher the safety level is. This can be expressed in a safety factor: AST = (safety factor) x RST.
What is the probabilistic building life time, related to the safety factor AST/RST for compartmentation and load bearing structure? Of course tha answer depends on the function, size and lay-out of the building. What is the acceptable probabilistic life time for a fire resilient building, compared to a building according to the building code?
In case of fire: Leave the building?
Stay-in-place concept vs. evacuation concept: reliability and redundacy.
In case of fire the personal safety of building occupants is guaranteed by the escape routes. When escape routes are blocked or cannot be used by the building occupants, personal safety has to be guaranteed in a different way. By creating very reliable lines of defense in the building (reliable fire and smoke resistant separation constructions and load bearing structure) a ‘stay-in-place’ concept might offer a solution. In this concept only the building occupants in the burning compartment evacuate, while other building occupants stay in their safe compartment. This concept is future proof for an ageing population.
What is the reliability needed for the above mentioned lines of defense, to realize a stay-in-place concept that provides a safety level comparable to a normal evacuation concept? Is it possible to add redundancy to a stay-in-place concept?
Reliability of fire and smoke compartmentation, depending on the safety concept
Fire and smoke compartmentation are ‘lines of defence’ in a performance based approach of fire safety. Although compartmentation is only a barrier in fire and smoke propagation, not directly related to personal safety (the main objective in fire safety), an extremely reliable barrier means that the consequences of fire and smoke are limited to a specific area or compartment in the building. Outside this area building occupants are safe, there is no need for evacuation. In that case a ‘stay-in-place concept’ can be seen as a redundant measure for an ‘evacuation concept’.
What reliability for fire and smoke compartmentation is needed in case of an evacuation concept according to the building code? And what reliability for fire and smoke compartmentation is needed when a stay-in-place concept is applied in case of fire?
Reliability of fire and smoke compartmentation in case of fire can be expressed in fire and smoke resistance. Also adjoining (external) constructions, like facades and roofs, connected to the separation construction, must be taken into account, because they influence the fire and smoke resistance of the separation construction.
Fire risks of energy transition in existing residential buildings - the building envelope
Reducing the influence of the building envelope on the failure probability of fire and smoke resistant separation constructions
A popular renovation concept for existing residential buildings is to add a new thermally well insulated façade to the existing façade. The new façade elements contain combustible insulation material and create also a cavity between the new and the existing façade. Both insulation layer and cavity introduce a risk of fire propagation from one compartment to another.
The reliability of fire and smoke resistant separation constructions is depending on the adjoining constructions, like the façade. The Grenfell fire in London is an example of bypassing the fire and smoke resistant separations constructions by the façade. Nowadays, there is a lot of discussion about fire safe façades. When the right fire class (EN 13501-1) is applied, we assume that the façade is ‘fire-safe’ and cannot easily be ignited. This assumption links to prescriptive requirements in the Building Code, but doesn’t prevent the risk of bypassing the fire and smoke compartmentation.
However, not all façade fires ignite the compartments behind that façade. When a façade fire is not hazardous for the compartments behind the façade, there is no need to prevent the risk of bypassing the fire compartmentation. What are the distinguishing factors for igniting a fire compartment behind the façade?
How do we design the joint between façade and fire and smoke resistant separation construction? And what reliability is needed to minimize the risk of the spread of fire and propagation of smoke from a compartment to all other compartments behind the façade?
Fire risks of green façades
Green walls and living façades: a riskful addition of fire load?
Green façades are gaining popularity in sustainable building, especially to connect the building with its (green) environment. It is possible to create green façades that meet the required fire class. In the Netherlands a fire class B (EN 13501-1) is required for new buildings. However, the fire class has nothing to do with the combustibility of the façade and the fire risks introduced by the green façade. Think about the threat of a localized fire close to the façade, or a wild fire approaching the building, or an external flame in case of a post flashover compartment fire in the building. An irrigation system could help, but also the construction of the façade is important. It is important to prevent bypassing the fire compartimentation inside the building by a façade fire. Experimental research in the fire lab will be necessary to get insight in the ignition risks and the risk of fire spread in the façade.
Multi-storey residential buildings iin CLT - Fire resilience as boundary condition?
Fire resilience as additional requirement to fire resistance
CLT (cross aminated timber) is a popular construction material for new residential buildngs, because of the CO2-storage in the building. Is it necessary to prevent sustainable CLT residential buildings from a burn down scenario in case of fire? A burn down scenario is an acceptable scenario according to the Building Code, as long as the building occupants have enough time to evacuate. However, in case of a building with high sustainability and durability standards a burn down scenario decreases the sustainability and durability of the building. Fire resilience can be seen as boundary condition for sustainable buildings. When the construction material of a building is combustible this is a major challenge!
There are already lots of experiments available related to the combustion of CLT with different thermal loads. These experiments can be used in a natural fire concept. The natural fire concept determines when the thermal action on CLT constructions is sufficieently decreased to reach a self-extinguishing effect.
A new fire curve for residential functions?
Most residential functions contain small rooms. In small rooms the fire load never is uniformly distributed. This means that the so called t-squared curves, used as design curves for natural developing fires don’t give a realistic fire development in small rooms. Is it possible to develop a new design fire for residential functions?
A traveling localized fire in a large compartment
In large compartments with a relative low fire load density a developing fire might need a lot of time before flashover conditions are reached in the fire compartment. The t-squared design RHR-curves for fire development are not applicable in these compartments, because the fire will extinguish after some time from the axis of fire origin, due to the low fire load density. What are the consequences when taking into account the extinguishing process from the axis of fire origin for the building users and constructions, exposed to the fire? How does the thermal action on constructions of this localized traveling fire compare to the thermal action of a post flashover fire with the same fire load density?
By comparing several combinations of compartment dimensions and fire load density it might be possible to create a design guideline.
Biuminous and plastic roof coverings under PV panels
Combustible roof coverings under PV panels - ignition risk
Bituminous and plastic roof coverings underneath an array of PV paneld are exposed to high radiation fluxes and fire brands in case of fire in the PV system. In most cases flat roofs contain a plastic insulation layer (EPS, PUR, PIR,…). When the roof covering ignites also the insulation layer will start burning, resulting in a roof collapse and fire spread to the fire compartments inside the building. What is the probability of this scenario and how can we prevent ignition of the roof covering by radiation flux or fire brands? Experimental research in the fire lab will be necessary, accompanied with a literature review and a simulation study.
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