What green building doesn’t get about hazards vs. risks

What green building doesn’t get about hazards vs. risks

Guest post by Stacy Fitzgerald-Redd 

Green building is about making buildings better, both for occupants and the broader environment. It has become mainstream because it is about creating better buildings, and who doesn’t want that? But before you can make better, greener buildings, you need to truly understand their impact on both occupants and the environment. A proper understanding of these impacts requires data derived through scientific research. It is peculiar, then, that the green building movement has strayed from its scientific roots when it comes to the treatment of the risks presented, or not, by various materials and compounds found in our buildings.

We talked science, now let’s talk math, specifically, one simple equation that explains how you correctly assess risk:

Hazard x Exposure = Risk

To understand this equation, we first need to have a proper understanding of the terms involved.

HAZARD – A hazard is anything that could potentially cause harm.  In reality, everything can cause harm in some manner.

RISK – A risk is the chance that someone will be harmed.  Whether someone will be harmed really depends on the level of exposure and the intensity of the exposure.

To illustrate the difference between hazard and risk, think of a tiger:

A TIGER IN A ZOO IS A HAZARD

A TIGER IN YOUR LIVING ROOM IS A RISK

A real world illustration can be made with the use of borates by different insulation manufacturers.  Borates are used in the manufacture of fiber glass insulation.  These borates provide properties that enable the fibers to be shaped and molded into different products.  The borates are embedded in the product and would never be released to the end-user.  Therefore, the borates, as used in fiber glass insulation, are not a risk because no one is going to be harmed.  Borates are also used in cellulose and other insulation products as a fire retardant.  The borates provide a coating on the cellulose fibers to reduce the fire threat that inherently exists in cellulose insulation.  If someone touched the cellulose insulation, they would have immediate dermal contact with borates.  Therefore borates, as used in cellulose insulation, are a risk. 

The borates comparison emphasizes that exposure is an essential element for risk to be present.  In the example of the tiger, immediate or imminent exposure is the key difference between hazard and risk.  This same concept of risk is demonstrated in yet another context – exposure to the sun.

 

In fact, exposure to the sun effectively illustrates the importance of placing risk in perspective.  As the picture makes clear, the risk presented by the sun can be effectively managed. Yet the sun is listed by the International Agency for the Research on Cancer (“IARC”) as a known carcinogen.  Radiation has been shown to be implicated in many forms of cancer.  Of the radiation received by an average American, 82 percent comes from natural sources.[1]  In fact, most naturally occurring substances are poisonous[2] (this surprising fact calls into question the notion that “natural” necessarily means better or safer, but that is a topic for another day).

Electricity, water, the sun, and almost everything else we encounter on a daily basis are hazards in that they can cause harm, but somehow we manage to make it through the day without incurring injury or serious harm.  Actually, in many ways we benefit from these hazards. How is that? It is because many of these hazards do not pose a serious risk because they are managed.

So how has green building gotten this wrong? The Living Building Challenge “Red List”[3] is a good example. This is a list of materials and chemicals that cannot, under any circumstances or in any quantity, be used in a building seeking Living Building certification. What is often debated with this list, and others like it, is what compounds belong on the list. However, with a proper understanding of how to assess risk, isn’t it clear that what we should be talking about is the idea of a list itself? How can a simple list of compounds, with no consideration of context (exposure), effectively speak to risk? The fact is it cannot. Lists, at best, can speak to hazards, but the absence of any consideration of exposure means they cannot speak to risk.

Lists are appealing in their simplicity. However, buildings are not simple, and science is not either. Both building professionals and consumers need be wary of the misleading allure that a simple list is the proper way to assess risk. For the green building movement to be true to itself it needs to acknowledge the complexity of risk. Failure to do so would mean a movement once grounded in science has truly lost its way.

Stacy Fitzgerald-Redd is director of communications for the North American Insulation Manufacturers Association (NAIMA).


[1] Larry Laudan, The Book of Risks (New York: John Wiley & Sons,, Inc., 1994), p. 75.

[2] Ibid. at p. 131.

[3]  Living Building Challenge Standard  (Red List can be found on page 44 of the standard)


Topics: Building Green, Healthy Homes, Indoor Air Quality, Insulation, Sustainability Trends & Statistics, Sustainable Products, Thermal Envelope


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