Author: Brian Meacham, Brandon Poole, Juan Echeverria and Raymond Cheng, Worcester Polytechnic Institute. Re-posted by permission of Brian Meacham NFPA
Introduction
Many new commercial facilities are being designed and constructed with an objective of achieving a “green building” certification. There are many sustainable building features and products that singly or together may have an impact on fire safety unless there is a design approach which mitigates those effects. The Foundation commissioned this study to develop a baseline of information on the intersection of “green building” design and fire safety and to identify gaps and specific research needs associated with understanding and addressing fire risk and hazards with green building design.
Executive Summary:
A global literature review was undertaken to (a) identify actual incidents of fires in green buildings or involving green building elements, (b) identify issues with green building elements or features which, without mitigating strategies, increase fire risk, decrease safety or decrease building performance in comparison with conventional construction, (c) identify reports, studies and best practice cases which speak to the issue of addressing fire risk introduced by specific green building design elements, and (d) identify research studies in which building safety, life safety and fire safety have been incorporated as an explicit element in green building indices. In addition, consideration was given to how one might express the level of increased risk or hazard, or decreased performance, associated with fire performance of green building features. Steps were also taken to identify gaps and specific research needs associated with understanding and addressing fire risk and hazards with green building design. Brian Meacham et al, Fire Safety Challenges of Green Buildings (Fire Protection Research Foundation, 2012), p.2
When was the last time you had a fire behavior class?
If you were honest it has probably been several years and most likely half of the class slept or paid very little attention because most firefighters like hands on drills were they can tear up stuff.
Those that have done fire behavior training recently what materials did you use? Because there has been major changes to fire development in the modern fire environment and most text books have not caught up.
Hopefully this post will help bring a lot of new material from UL , NIST and many other places together in a post that firefighters can use to train their next shift.
Fire Dynamics
Fire Dynamics is the study of how chemistry, fire science, material science and the mechanical engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior. In other words, Fire Dynamics is the study of how fires start, spread and develop. But what exactly is a fire?
Defining Fire
Fire can be described in many ways – here are a few:
NFPA 921: “A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities.”
Webster’s Dictionary: “A fire is an exothermic chemical reaction that emits heat and light”
Fire can also be explained in terms of the Fire Tetrahedron – a geometric representation of what is required for fire to exist, namely, fuel, an oxidizing agent, heat, and an uninhibited chemical reaction.
Measuring Fire
Heat Energy is a form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state (NFPA 921). Heat energy is measured in units of Joules (J), however it can also be measured in Calories (1 Calorie = 4.184 J) and BTU’s (1 BTU = 1055 J).
Temperature is a measure of the degree of molecular activity of a material compared to a reference point. Temperature is measured in degrees Fahrenheit (melting point of ice = 32 º F, boiling point of water = 212 º F) or degrees Celsius (melting point of ice = 0 º C, boiling point of water = 100 º C).
º F
Response
98.6
Normal human oral/body temperature
111
Human skin begins to feel pain
131
Human skin receives a second degree burn injury
162
Human skin is instantly destroyed
212
Water boils and produces steam
284
Glass transition temperature of polycarbonate
446
Melting temperature of polycarbonate(Mask)
>572
Charring of modern protective clothing fabrics begins
>1112
Temperatures inside a post-flashover room fire
Heat Transfer
Heat transfer is a major factor in the ignition, growth, spread, decay and extinction of a fire. It is important to note that heat is always transferred from the hotter object to the cooler object - heat energy transferred to and object increases the object’s temperature, and heat energy transferred from and object decreases the object’s temperature.
CONDUCTION
Conduction is heat transfer within solids or between contacting solids.
courtesy of NIST
courtesy of NIST
CONVECTION
Convection is heat transfer by the movement of liquids or gasses.
courtesy of NIST (convection on firefighter)
RADIATION
Radiation is heat transfer by electromagnetic waves.
courtesy of NIST (Radiation on the firefighter)
Fire Phenomena
Fire Development is a function of many factors including: fuel properties, fuel quantity, ventilation (natural or mechanical), compartment geometry (volume and ceiling height), location of fire, and ambient conditions (temperature, wind, etc).
Traditional Fire Development The Traditional Fire Development curve shows the time history of a fuel limited fire. In other words, the fire growth is not limited by a lack of oxygen. As more fuel becomes involved in the fire, the energy level continues to increase until all of the fuel available is burning (fully developed). Then as the fuel is burned away, the energy level begins to decay. The key is that oxygen is available to mix with the heated gases (fuel) to enable the completion of the fire triangle and the generation of energy.
Fire Behavior in a StructureThe Fire Behavior in a Structure curve demonstrates the time history of a ventilation limited fire. In this case the fire starts in a structure which has the doors and windows closed. Early in the fire growth stage there is adequate oxygen to mix with the heated gases, which results in flaming combustion. As the oxygen level within the structure is depleted, the fire decays, the heat release from the fire decreases and as a result the temperature decreases. When a vent is opened, such as when the fire department enters a door, oxygen is introduced. The oxygen mixes with the heated gases in the structure and the energy level begins to increase. This change in ventilation can result in a rapid increase in fire growth potentially leading to a flashover (fully developed compartment fire) condition.
Changes in Today’s fires:
Modern Building Construction + More Plastics = Extreme Fire Behavior
Did you notice that fire development has changed? There is early decay now! We as firefighters need to share this with all firefighters especially ones that havn’t been to fire behavior class in some time.
Energy Efficient Modern Building Construction:
Effective Insulation
Properly installed and inspected insulation in floors, walls, and attics ensures consistent temperatures with less energy use. The result is lower utility costs and a quieter, more comfortable home.
High Performance Windows
Energy-efficient windows use advanced technologies to keep heat in during the winter and out during the summer. They also block damaging ultraviolet sunlight that can discolor carpets and furnishings.
Tight Construction and Ducts Homebuilders Making a Difference:
Advanced techniques for sealing holes and cracks in a home’s “envelope” and in heating and cooling ducts help reduce drafts, moisture, dust, pollen, pests, and noise. A tightly sealed home improves comfort and indoor air quality while lowering utility and maintenance costs.
The tactical considerations include:
Stages of fire development:The stages of fire development change when a fire becomes ventilation limited.
It is common with today’s fire environment to have a decay period prior to flashover which emphasizes the importance of ventilation
Forcing the front door is ventilation: Forcing entry has to be thought of as ventilation as well.
While forcing entry is necessary to fight the fire it must also trigger the thought that air is being fed to the fire and the clock is ticking before either the fire gets extinguished or it grows until an untenable condition exists jeopardizing the safety of everyone in the structure.
No smoke showing:A common event during the experiments was that once the fire became ventilation limited the smoke being forced out of the gaps of the houses greatly diminished or stopped all together.
No some showing during size-up should increase awareness of the potential conditions inside.
Coordination: If you add air to the fire and don’t apply water in the appropriate time frame the fire gets larger and safety decreases.
DON’T FORCE DOOR UNTILL YOU HAVE A CHARGED HOSELINE IN PLACE!
The most unique feature of the INhome is the biowall. The biowall is a home air filtration system that utilizes plants placed in a vertical wall, which remove harmful chemicals that can accumulate in homes that are tightly sealed like the INhome. Air from the home is drawn through the plant wall where the chemicals are removed by the plants and used as a food source. The wall requires very little maintenance and is even designed to water itself. The biowall improves the air quality in the home, saves energy, and provides a calming ambiance by bringing nature inside the home.
Bio Wall
One of the things that I really liked about the home was that it was sprinkled! GO PURDUE !!
Habitat for Humanity was able to build green by using sustainable materials and installing eco-friendly products, such as tankless water heaters, geothermal exchange heating and cooling systems, structural insulated panels, cool roofs, low-VOC paints, and copper fire sprinkler systems.
These 17 single-family homes are 1,200 square feet, and consist of three- and four-bedrooms, and one and a half baths. They were designed to complement the current architecture in the neighborhood, and all of the homes are pending LEED Platinum certification.
Structural Insulated Panels have came on strong in green construction in the midwest. I will have more information in later post about structural insulated panels.
If you are a member of the International Society of Fire Service Instructors you can access a free training program I have developed on structural insulated panels. It will be located in the community resource section.
International Society of Fire Service Instructors web site:
Greetings to all my Brother & Sister Firefighters!
What is Green Maltese? That was the question you thought as you clicked on this blog, and I am happy that you chose to find out.
Green Maltese: My goal is that Green Maltese becomes the place where fire service leaders can gain and share knowledge about the Green Movement and anything about Green (Sustainable) Building Construction.
Future Topics:
Green Buildings
Green Roofs
Recycled Materials
Photovoltaic (PV) Solar Power Systems
Green Building Rating Systems
Structural Insulated Panels
Daylighting
About Me: My name is John Shafer. I am a 16-year fire service veteran of career and volunteer departments, an Indiana regionally recognized instructor on building construction, fireground search and command management, and I’ve traveled throughout the State of Indiana delivering specialized training programs on building construction, fireground search and firefighter safety. I am a member of the International Society of Fire Service Instructors, have served as an advisor to the Indiana Department of Homeland Security for the state’s development of the Fire Training System of Indiana, and have assisted the development of the District 7 Training Council and the District 7 Response Task Force.
Special thanks to Chris Hebert Go Forward for allowing me the oppurinty to make this dream of mine come true, and Rhett Fleitz Fire Critic – FireCritic.com for his help and inspiration.
This blog is dedicated to educating and saving firefighters lives by sharing information about current and future issues concerning building construction. Please join me on the journey, and be inspired!
