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3. FIRE SAFETY

To varying degrees, reducing the risk of fire damage to both buildings and their contents is a function of all architecture. The problem originates in the use of carbon-based materials that, under the right circumstances, may enter into a state of rapid combustion. Fire is not something external to such materials, but rather an alternative state of being triggered by ignition and sustained by heat, in the presence of oxygen. Where carbon-based materials are used (ubiquitously in buildings), and where sources of ignition are plentiful (candles, matches, lightning, gas lamps or stoves, fireplaces and chimneys, boilers and furnaces, faulty electrical connections, and so on), it is not surprising that rooms, buildings, and entire sections of cities often burn. ¹

The function of fire safety in buildings has evolved over the years, following a trajectory involving increasingly greater control over both the initiation and spread of fire. Historically, the first significant functional fire safety goal was to prevent urban conflagrations, that is, to prevent fire spreading from a single building of origin to adjacent structures; the second goal was to limit fire damage to a building's floor of origin; and the third was to limit fire damage to the room of origin. To accomplish this, fire safety regulations governing the design of buildings have become increasingly rigorous and comprehensive, including requirements for more effective passive and active systems.

Passive systems refer, in general, to physical barriers that "compartmentalize" any given building into smaller zones from which a fire, having started, is not likely to transgress. The most basic compartment is the "story," created with continuous horizontal floor-ceiling assemblies that limit a fire to the floor of origin. Compartments can also be defined by continuous vertical elements, such as fire barriers and fire walls. Clearly, continuity of elements that define the boundaries of compartments is critical, so that openings in them must be limited and carefully designed.

Active systems refer, most commonly, to automatic sprinklers. On the one hand, these systems have proved to be incredibly effective in limiting fires to their room of origin, knocking them out in place before they have a chance to grow larger. The most common systems rely on water under pressure within a grid or loop of pipes placed just below the ceiling. On the other hand, fire sprinklers do not always work as intended. The National Fire Protection Association calculated a sprinkler failure rate of about 12 percent, taking into account both sprinkler operation and sprinkler effectiveness: "In fires considered large enough to activate the sprinkler, sprinklers operated 92% of the time. Sprinklers were effective in controlling the fire in 96% of the fires in which they operated. Taken together, sprinklers both operated and were effective in 88% of the fires large enough to operate them." ² Thus, it is dangerous to rely entirely on sprinklers, and passive protection remains important. It is thus a fairly big deal that the historic trajectory of increasingly more stringent requirements for both passive and active protection has seemingly come to an end, as modern building codes have incorporated so-called sprinkler trade-offs that allow reductions in passive protection and increases in both floor area and building height when sprinkler systems are used. ³

Both passive and active fire safety elements show up in building codes, but not always as absolute requirements. Instead, the mandated function of fire safety is accomplished by considering the risk of damage, death, and injury for each particular project, based on a number of fire science principles. First, the impact of "fuel" (combustible material consisting of the building itself or its contents) available for a fire must be considered. This can be done in several ways: by employing the basic passive strategy of compartmentation (i.e., using fire barriers, fire walls, horizontal assemblies, etc.) to subdivide a large space into smaller ones that have been separated from each other so that a fire is contained within the compartment where it starts; by adding active automatic sprinkler systems; and by enforcing floor area and height limits based on the occupancy of the space and the construction type of the building. The occupancy refers to the type of activity anticipated in the building, and activities that present a relatively greater risk of death or property damage—for example, assembly uses where lots of people gather in confined spaces, or storage/library stack areas where large quantities of combustible material such as books and magazines are intrinsic to the activity itself—have more stringent limitations on both floor area and height above the ground. The construction type refers to the materials used to construct the building and, in particular, whether they are combustible (e.g., made of wood, plastics, or other carbon-based materials), non-combustible (e.g., made of steel, reinforced concrete, or masonry), or protected with a fire-resistant covering. A building made with a more fire-resistant construction type can have greater floor area and building height. In fact, buildings with the most fire-resistant construction type (except when containing high-hazard occupancies) can be built with unlimited floor area and unlimited height, at least from the standpoint of fire safety—floor area and height may well be constrained by zoning ordinances that are based on considerations having nothing to do with fire safety.

Second, it is necessary to reduce the risk of fire spreading from a single building to adjacent properties. As the distance from a building's perimeter to its bounding property lines (its so-called frontage) increases, the risk of fire "jumping" from that building to adjacent construction is reduced, and additional floor area is permitted. On the other hand, to the extent that a building's exterior wall is constructed close to, or actually on, a property line adjacent to another piece of property, regulations regarding both the fire-resistance of that wall, as well as the amount and the required fire protection of openings in that wall, become more restrictive. At the extreme, it is common to prohibit all openings in exterior walls built on a side or rear lot line.

Third, it is necessary to reduce the risk of inadvertent ignition by regulating electrical installations and appliances that produce heat and fire (such as stoves). Societal trends that discourage (or even prohibit) smoking in buildings also help eliminate what remains a dangerous source of ignition, especially in residences: "Smoking materials, including cigarettes, pipes, and cigars, started an estimated 17,200 home structure fires reported to U.S. fire departments in 2014. These fires caused 570 deaths, 1,140 injuries and $426 million in direct property damage." ⁴

Fourth, it is necessary to enable fire suppression by encouraging the use of automatic sprinkler systems and by providing access (including additional fire stairs in tall buildings) and water (including the installation of standpipes) to trained firefighting personnel.

Fifth, it is necessary to exhaust or otherwise control smoke originating from a fire. Smoke is the largest cause of death in building fires, and much of the logic of compartmentation has to do with restricting the movement of this deadly gas. The classic "violation" of the compartmentation principle would occur in multi-story atriums, except that special building code provisions have been developed to ensure that smoke originating from fires can be controlled and, usually, exhausted from the top of such spaces. Otherwise, building codes generally permit openings in floor-ceiling assemblies to connect no more than two adjacent stories.

Sixth, it is necessary to provide adequate and protected means of egress (exits), along with detection and alarm systems, so that people are aware of, and can escape from fire in buildings. The number of exits for a room, or for an entire building story, is determined by the number of occupants in that room or story. In U.S. practice, rooms with no more than 49 occupants generally need only one exit. Some entire buildings with low occupancy (and no more than one or two stories) can also be built with a single exit, but this is atypical: most buildings need at least two means of egress.

The function of fire safety is implemented in buildings, not because owners and architects think it's a good idea, but because the historic experience of fire damage (including loss of life, injury, and loss of property) has led to the evolution of laws mandating specific fire safety provisions. Yet there is a difference between fire science and fire codes. Where fire science seeks to explain how fires start in buildings, how they spread, what sort of risks they pose, and how they can be prevented, controlled, and suppressed, fire codes attempt to prescribe requirements for construction that reconcile the costs of fire (i.e., death, injury, and property loss) with the costs of fire safety measures. Fire codes are therefore political documents that use engineering and scientific knowledge to support political goals. Even so, we can take code requirements as the de facto functional prerequisites for fire safety, since—for society as a whole if not for every individual building—these requirements provide a politically acceptable level of safety. That a political decision-making process defines this architectural function—with the underlying fire science often obscured in the prescriptive text and, in any case, not well understood by architects and building owners—gives rise to numerous misconceptions about fire safety and results in various types of non-compliance with current regulations.

Fire safety requirements are the outcome of political decisions based on the consideration, if not explicit calculation, of costs and benefits. This argument can be best understood by examining how governments have historically intervened to limit damage from fire, starting with the periodic conflagrations that routinely destroyed entire urban areas, and continuing with efforts to find cost-effective means to reduce and control fire damage within individual buildings.

Urban conflagrations were hardly limited to those fires famous for their impact on the history of architecture, notably the Great Fire of London in 1666 and the Great Chicago Fire in 1871 (Fig. 3.1). Virtually all cities experienced major conflagrations, and the causes were well known: combustible materials used for building walls, floors, and roofs; narrow streets which allowed fires to spread easily from one building to another; flammable material stored near ignition sources; and so on. In London before 1666, "the greater part of the houses were still half timbered with pointed gables facing the street." ⁵ The London fire began as a

strong east wind carried sparks from the burning timbers across the narrow lane on to hay piled in the yard of an inn opposite. The inn caught, and from there the flames quickly spread into Thames Street, then, as now, a street famed for its wharfingers. Stores of combustibles—tallow, oil and spirits—were kept in its cellars, whilst hay, timber, and coal were stacked on the open wharves near by. ⁶

Conditions in Boston, immediately before the Great Fire there in 1760, were similar: wood frame houses with combustible siding and roofing materials were common. Large amounts of combustible material could be found inside buildings, including commercial products in residential contexts ("rented rooms doubled as piecework shops, and leather, petroleum products, and the raw materials for manufacturing textiles covered their floors"). Ignition sources including candles and "lard or whale oil lamps with on open wick" were present. Narrow streets allowed fires to spread beyond the building of origin; manufacturing technologies commonly relied upon fire, often operating immediately adjacent to combustible materials ("Breweries, glassworks, tanneries, forges, candle-makers, dyers, and potters all had to use ovens or open-pit fires. Next to the flames were fuel sources"). Barns contained straw and hay. Armories and forts contained gunpowder. Combustible materials were stored in shipyards (e.g., rope, tar, sails, etc.). Combustible soot was present in chimneys directly adjacent to thatch roofs. And flagrant violations of existing, enacted, fire regulations (e.g., those mandating tile roofs or masonry walls) were common. ⁷

The potential damage from urban conflagrations was well known and well understood; and it was increasingly clear that economic costs of such fires exceeded the costs of remediation: "The evils of the old [i.e., London before the Great Fire] had been glaring, its critics legion. For many years, from the King downwards, men had striven to provide remedies." ⁸ What stood in the way of adopting safer building practices was not knowledge, but the unwillingness of individual property owners to transcend their own immediate interests: "Annual fire losses represented a waste of resources for the nation as a whole, but individuals were unwilling to shoulder the burden, in the form of more expensive buildings, to help reduce this loss." ⁹ In the case of the Boston fire described above, the economic motivation of individual owners to continue building with combustible materials was clear: "For all the damage the [earlier] Great Fire of 1711 caused and the handwringing that followed, Boston remained a wooden city because the cost of rebuilding in wood was lower than the cost of fireproofing." ¹⁰

Strategies that required large-scale planning and regulation were only possible with state intervention. Yet, as can be seen in the aftermath of the London fire, proposals that require state intervention to correct problems for their own sake, that is, proposals coming primarily from an aesthetic, idealistic, or moral standpoint, are not generally successful. Christopher Wren's radical vision for central London, one among several plans submitted immediately after the fire, was famously rejected, according to Wren's grandson, because of "the obstinate Averseness of a great Part of the Citizens to alter their old Properties, and to recede from building their houses again on their old Ground & Foundations." ¹¹ On the other hand, there were instances where private owners implemented voluntary standards for their own buildings, based explicitly on cost–benefit calculations—for example, taking into account the added costs of insurance for buildings that were not adequately fireproofed. Even so, while insurance costs may have had some effect on encouraging fire-safe practices, the idea that such a market-driven mechanism is sufficient to promote a rational allocation of resources to fire safety is questionable. As Sara Wermiel argues: "Unfortunately, the intense competition in the fire insurance industry made it difficult for companies to stick to a rate schedule, even if they wanted to. They were more likely to charge whatever it took to win or keep a customer." ¹² In general, it is unlikely that individual building owners would spend money for technologies that improved fire safety but were not mandated by building codes.

In the case of fire safety, state intervention on behalf of overarching economic interests had to contend with two major obstacles: first, uncertainty about the scope of the problem (fires happen in a probabilistic context that makes precise calculations of costs difficult); and second, the resistance of individual owners who would experience higher initial costs. As a result, laws compelling owners to adopt fire safety measures originate at points of greatest certainty (i.e., where the recent experience of fire damage is unequivocal) and where the results of inaction are calculated to have unacceptable negative consequences. Thus, an initial proclamation issued only one week after the Great Fire of London established the basic conditions for preventing future conflagrations: "Rebuilding was to be carried out in brick or stone, and all 'eminent and notorious streets' so widened that a fire could not cross from one side to the other." ¹³ In an analogous manner, the notorious Triangle Shirtwaist Factory Fire of 1911 in New York City "proved to be a turning point in the history of fire safety practice." ¹⁴ As various technologies to promote fire safety are introduced in limited ways, it becomes possible to increase, or decrease, their application over a broader range of building types, depending upon the actual costs and benefits experienced in these trial applications.

For example, automatic sprinkler systems in the U.S. were first generally used in Associated Factory Mutual mill buildings in the late 19th century—one of several fire safety measures required for lower insurance rates—but were rarely used in any other context until they were first mandated in building codes. Initial sprinkler requirements were limited to theaters, and only for the proscenium opening and stage. ¹⁵ As evidence of their effectiveness became known, and experience with their use made costs of installation more predictable, it became possible to more convincingly cite their economic benefits for an increasing range of applications. Other fire safety measures followed the same pattern. When outside fire escapes became required in some contexts, other measures that provided greater fire safety (e.g., fireproof stairs and corridors) were considered but rejected as too costly: "In dropping the requirement for fireproof stairs [per the 1871 revision of the 1867 NYC building law] and making fire escapes the all-purpose solution for emergency egress, lawmakers most likely accommodated the preferences of landlords for a cheap solution." ¹⁶ The costs and benefits of sprinklers versus passive systems (like fireproof stairs and corridors) are still being argued. New building codes have radically reduced the requirements for passive protection in cases where sprinkler systems are used:

In fact, there are literally hundreds of code-approved provisions to eliminate or reduce fire and smoke control features in the IBC [International Building Code] when sprinklers are installed. This trend to reduce or eliminate passive features while installing more sprinklers flies in the face of traditional views on fire safety as espoused by generations of fire scientists, fire protection engineers, and published experts. ¹⁷

Even after the collapse of the World Trade Center buildings in 2001 as a result of internal fires (where both passive and sprinkler systems proved ineffective), recommendations to strengthen building code requirements for fire safety have been only partially implemented, based on the cold calculation of costs and benefits. National Institute for Standards and Technology (NIST) recommendations for improved fire safety standards have been criticized on the basis of an implicit cost–benefit criterion:

From a theoretical standpoint, a requirement for redundant water supplies for a sprinkler installation seems logical in order to reduce the required fire ratings of the structural frame of a building. Again, our real world experience over the past 25 years indicates that providing a redundant water supply is unnecessary. A single tragic event, where providing a redundant water supply wouldn't have made any difference anyway, shouldn't change what our real world experience tells us. ¹⁸

The function of making buildings safe from fire is routinely undermined by both building users—who prop open doors that are part of fire barriers separating offices from corridors, or corridors from exit stairs, and so on—and building owners, who have locked exits to keep workers from leaving (most infamously at the 1911 Triangle Shirtwaist Factory fire in New York City, where 146 garment workers died), or who have locked exits to keep customers from entering without paying (492 people were killed in the Cocoanut Grove nightclub fire in Boston in 1942 and 194 people were killed in the Cromañón Republic nightclub fire in Buenos Aires in 2004).

Instances of owners or builders lobbying against, or circumventing, fire safety regulations are a consistent thread within the historical evolution of fire protection. Even well into the second decade of the 21st century, U.S. requirements for fire sprinklers in one- and two-family homes—included in model building codes since 2006—are not required in most states at the time of this writing, as lobbyists have successfully argued for legislation specifically prohibiting implementation of this particular code provision: "U.S. homebuilders and realtors unleashed an unprecedented campaign to fend off the change, which they argued would not improve safety enough to justify the added cost." ¹⁹

In other words, by this logic, the added "benefit" of extra safety needs to somehow justify the added cost of residential sprinklers. But how are such calculations actually made? The first part of the equation—the added cost for residential sprinkler systems—is fairly easy to determine, being approximately one percent of the total construction cost in the U.S. (i.e., about $1.50 per square foot), or about $2,000 for a home otherwise costing $200,000. In contrast, the second part of the equation—accounting for "added safety" brought about by this fire safety measure—is harder to quantify, as it includes not only the cost of property damage due to fire, but also, somehow, the "costs" of death and injury. Based on 2016 U.S. data alone, 257,000 residential fires occurred in one- and two-family homes, accounting for 2,410 deaths (representing 81 percent of all civilian fire deaths), 7,375 injuries, and $4.9 billion in property loss. ²⁰ The average cost per residential fire, not including the cost of death and injury, is therefore about $19,000. On the other hand, prorating this property damage over all 75 million owner-occupied homes in the U.S., the yearly average property loss would be only about $65 per home. ²¹

But what about the risk of death and injury in such fires? Assuming 2.53 people per household and 2,410 deaths per year out of the 190 million people living in 75 million one- and two-family houses, the chance of dying in such a fire in any given year is about one thousandth of one percent. Looked at over an 80-year lifetime, the chance of any given individual dying in a one- or two-family house is closer to one tenth of one percent, or about 1 out of 1,000. But can the "costs" of those lost lives really be determined? It turns out that there is a considerable academic literature that purports to calculate the "value of life," all of it testifying to the insanity of an economic system in which the need for safety measures is determined by assigning a dollar value to each human life. Yet it is only by using such values (e.g., "estimates of the value of life in the U.S. are clustered in the $4 million to $10 million range, with an average value of life in the vicinity of 7 million" ²²) that such cost–benefit decisions can be made. Following the same logic used in the calculation of property loss, the average value of $7 million per fire death is multiplied by 2,410 deaths (in 2016) for a total loss of $16.87 billion. Divided by all 75 million owner-occupied homes, the yearly average loss of life becomes about $225 per home. The average cost of a fire injury is about one thirtieth that of a fire death, ²³ or $7 million divided by 30, which equals $233,333 per fire injury. Multiplied by the 7,375 injuries and then divided by all 75 million owner-occupied homes, the yearly average cost of fire injury becomes about $23 per home. Thus, the average total cost associated with maintaining the status quo—that is, eliminating requirements for sprinklers in one- and two-family homes, while assuming that such sprinklers would dramatically reduce the incidence of residential fire damage, death, and injury—is about $313 per home, per year, while the average cost of installing sprinklers is about $2,000. ²⁴

Even using these extremely rough calculations, it is easy to see why model code agencies have included requirements for such residential sprinklers in their model codes: a one-time "annuity" of $2,000 for sprinkler installation compares favorably with an annual stream of $313 to cover the prorated costs of fire damage, death, and injury, at least when the assumed discount rate does not exceed approximately 14 percent. However, it is also easy to see why opponents of sprinkler mandates have been successful in counteracting these model code provisions in many states. First, homeowners are not actively organizing to demand sprinklers in their homes, in large part because there is an extremely low probability of dying in a residential fire; second, for any politician voting on such measures, the cost–benefit calculation is not really that compelling, with the outcome hinging upon exactly which discount rate is chosen, and the difference between computed costs and benefits not really being that great; and third, for home builders (and realtors) working in a competitive market that includes existing homes—for which retroactive sprinkler installation is not required—an additional cost of $2,000 either makes their product more expensive (and therefore harder to sell) or reduces their profit, giving them an incentive to advocate strongly against such provisions.

The idea that cost may motivate architects, builders, or building owners to reduce levels of fire safety is central to many of the examples already given: the refusal of property owners after the Great Fire of London (1666) to agree to any reconfiguration of London's street plan that would negatively affect the value of their own property; the use of fire escapes instead of (more expensive and safer) interior fireproof stairways; the painfully slow implementation of automatic sprinkler requirements, even after their effectiveness had been demonstrated; state legislation that actually prohibits model code requirements for residential sprinklers in one- and two-family homes from being implemented—all of these examples demonstrate that reducing cost can be an important motivation for lowering fire safety standards. The negative impacts of such cost-saving measures cannot be precisely determined for any individual building but only in the aggregate, since the probability of any given building being damaged is certainly low and, in any case, unknown. It is usually only when individual buildings are actually damaged by fire, and especially in those disasters where many deaths occur, that criticism of cost-saving measures enters the public discourse. This occurred, for example, in the aftermath of the Grenfell Tower apartment fire in London in 2017:

Promising to cut 'red tape,' business-friendly politicians evidently judged that cost concerns outweighed the risks of allowing flammable materials to be used in facades. Builders in Britain were allowed to wrap residential apartment towers—perhaps several hundred of them—from top to bottom in highly flammable materials, a practice forbidden in the United States and many European countries. And companies did not hesitate to supply the British market. ²⁵

While cutting costs that reduce fire safety in buildings is widely criticized, at least after fire calamities occur, such practices are entirely consistent with the competitive, profit-seeking ethos of capitalism and are only effectively curtailed by governmental regulation and enforcement.

Notes

¹ A short, unpublished version of this introductory paragraph and the historical overview found later in this chapter were presented by the author as "What Sustainability Sustains," Hawaii International Conference on Arts & Humanities, January 2008.

² Ahrens, "U.S. Experience with Sprinklers."

³ Ahrens, "U.S. Experience with Sprinklers."

⁴ "Smoking," National Fire Protection Association, accessed January 7, 2020, here.

⁵ Rasmussen, London: The Unique City, 99.

⁶ Reddaway, The Rebuilding of London, 22.

⁷ Hoffer, Seven Fires, 21–31.

⁸ Reddaway, The Rebuilding of London, 31.

⁹ Wermiel, The Fireproof Building, 4.

¹⁰ Hoffer, Seven Fires, 32.

¹¹ Reddaway, The Rebuilding of London, 33.

¹² Wermiel, The Fireproof Building, 173–74.

¹³ Reddaway, The Rebuilding of London, 49.

¹⁴ Wermiel, The Fireproof Building, 10.

¹⁵ Wermiel, The Fireproof Building, 132–33.

¹⁶ Wermiel, The Fireproof Building, 191.

¹⁷ Licht, Impact of Building Code Changes.

¹⁸ Shulte, "Report on the World Trade Center," 16.

¹⁹ Robert Faturechi, "The Fire Sprinkler War, State by State," ProPublica, June 22, 2016, here.

²⁰ Haynes, "Fire Loss in the United States."

²¹ Statista, "Number of Owner Occupied Housing Units in the United States from 1975 to 2018," accessed November 10, 2019, at https://www.statista.com/statistics/187576/housing-units-occupied-by-owner-in-the-us-since-1975/ (has been updated at a new link).

²² Viscusi, "The Value of Life."

²³ Hall, Jr., "Total Cost of Fire," 24.

²⁴ Brown, "Economic Analysis of Sprinkler Systems."

²⁵ David Kirkpatrick, Danny Hakim, and James Glanz, "Why Grenfell Tower Burned: Regulators Put Cost Before Safety," New York Times, June 24, 2017 (my italics).

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contact | contents | bibliography | illustration credits | ⇦ chapter 2 | chapter 3 | chapter 4 ⇨
 

First posted 30 October 2023. Last updated 30 October 2023.