Permanent Fire Load of the Building Envelope

Abstract

Fire load, the total thermal energy released by the combustion of a material, is an essential part of determining a building’s fire performance and the associated fire protection strategies. Elements in a structure are typically categorized into two types of fire loads: permanent and temporary. Permanent fire loads represent the combustible materials in the building envelope. With the advent of energy
efficiency, polymer-based materials with unique burning behaviors have been utilized more in the building envelope. These, and other materials that experience delamination, charring, melting, etc., can affect the way permanent fire loads are quantified.
National guidelines prescribe the use of the heat of combustion (HoC), which is derived from grams of material and tested in controlled conditions through calorimetry techniques when calculating fire loads. Micro-scale tests to obtain HoC, e.g., Bomb Calorimeter and Microscale Combustion Calorimeter, indicate that the specimens do not represent large-scale behaviors and physical factors such as end-use of the material, ventilation factors, layering of materials, etc. Additionally, it has been examined that the current literature values that are derived from Bomb Calorimeter tests are deemed outdated and report underestimation or overestimation when calculating permanent fire loads.
The aim of the project is two-fold: carry out a theoretical examination of how permanent fire loads are calculated per country, and; utilize traditional and alternative approaches to obtain the Hoc for building envelope materials. By utilizing an increasing-scale testing approach, theoretical (Microscale
Combustion Calorimeter and Bomb Calorimeter) and realistic values (Cone Calorimeter and 1/3-scaled room corner test) for the Heat of Combustion were derived.
It was determined from the experimental design that the calculated fire load from the room corner tests results in the lowest fire loads, both permanent and temporary, because it considers systemic performance and material-to-material interaction. The presence of the non-combustible materials provided means to delay the burning of the combustible linings. Further, it was seen in the scaling of the
tests from micro- to final form of the samples, that the Cone Calorimeter is an attractive starting point to accurately represent permanent fire loads since materials could be tested as composites or in larger sizes vs. microscale tests.

Popular Abstract

As fire engineers, we continue to find ways to improve our understanding of how materials perform in the face of fire incidents. It has always been thought of that materials have different burning behaviors depending on factors such as available oxygen, composition, and even consideration of how materials are layered in a building construction. This has motivated the research to think ahead of such challenges, especially since more complex materials, with unique burning behaviors, are being used more and more. The burning question that merits to be answered for this dissertation is the following: with the increased use of polymers in building envelopes, how can we accurately obtain the energy that these materials release? The Total Energy released by the materials, technically termed the Fire Load, affects the severity of the fire and impacts the building design and the associated fire protection such as additional sprinklers and material selection.
In essence, the project employed two strategies to address this question. Firstly, a thorough examination of how fire loads are calculated per country was conducted. This is important to establish how Belgium, Sweden, The Netherlands, and the UK vary or are similar in how they approach fire loads. Secondly, experiments via traditional/micro-sample tests and alternative methods were done. Traditional/micro-sample methods, like the Bomb Calorimeter and the Microscale Combustion Calorimeter (MCC), are seen to be conservative because it completely ignites grams of material in controlled conditions. Nearly perfect energy is obtained from these tests. Cone Calorimeter and Room Corner tests are deemed appropriate to represent realistic values of the fire load since larger samples are used. Common building envelope materials such as insulation, calcium boards, and gypsum boards, plus a foot bench were tested in increasing scale. The Bomb Calorimeter and MCC use grams of material, the Cone Calorimeter use a 10x10 cm representative of the samples, and the Room Corner tests as a constructed room with the sample materials as the room elements.
It was determined from burning the materials in the experimental design that the calculated fire load or energy released from the room corner tests results in the lowest value. It was seen that in the room corner tests: effective construction of the room can delay the burning of the insulation housed between the calcium and gypsum boards; materials interact; and large sample behaviors such as delayed ignition can occur because of material thickness.
This thesis project aimed at demonstrating that alternative methods can be employed to give architects, designers, firefighters, and even lawmakers, more insights into how materials perform. More knowledge supports more informed decisions regarding fire strategies around fire loads. Beyond the traditional methods, fire engineers may use alternate methods that consider more real-life scenarios. Overall, the research project looks to add to continued efforts to better understand building materials and consider nuances such as material interaction and the benefits of effective construction.

• author: Pondevida Jamero, Gizelle Danine
• supervisor: Patrick Van Hees
• organization: Division of Fire Safety Engineering
• alternative title: An examination of the Heat of Combustion in theoretical and realistic combustion processes using an increasing-scale testing approach
• course: VBRM05 20231
• year: 2023
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Permanent fire load, temporary fire load, fire load, building envelope, insulation, building content, upholstered furniture, heat of combustion, MCC, bomb calorimeter, cone calorimeter, room corner test.
• report number: 5695
• other publication id: LUTVDG/TVBB—5695--SE
• language: English
• id: 9120048
• date added to LUP: 2023-06-09 15:54:55
• date last changed: 2023-06-13 15:40:15