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The Next Big Thing in Healthy Building is Microscopic

Alan Scott

Healthy building is an increasingly important topic in the broader sustainable built environment arena, but much of the focus is on active designhealthier materials, and designing systems for air quality and comfort. These are important common sense features, but one of the more interesting areas of research in healthy building is something much smaller (microscopic, in fact!) and naturally occurring: microbes.

Many of us have some degree of germphobia and have been conditioned to fear the things we cannot see, and for good reason-touching a doorknob or shaking a hand and than absentmindedly scratching your nose can land you in bed with a miserable cold, flu or worse. To minimize the threat, we wash with anti-bacterial soaps and use harsh cleaning products to hyper-sanitize the surfaces around us.

But what if this shotgun approach to killing bad bugs was actually setting us up for worse infections? We know that bioclimatic design with passive, climate-responsive approaches to maintaining indoor comfort can offer a more efficient and effective alternative to using brute force energy in mechanical systems. Similarly, embracing the naturally occurring microbiome could offer a better solution to maintaining healthy indoor environments, compared to hyper-sanitization.

Microbes are everywhere. The human microbiome includes a microbial cloud, a unique personal cloud of invisible organisms (bacteria, fungi, etc.) that hovers around us. The total number of cells in the microbiome that is in and around you outnumbers your own cells 10 to 1. According to research by the University of Oregon's Biology for the Built Environment Center (BioBE), your body hosts a whole ecosystem of millions of living things. While some of these are potential pathogens to be avoided, scientists are just beginning to understand the array of other beneficial bacteria and fungi, which can have significant health benefits.

You may have heard of the hygiene hypothesis that suggests exposure to dirt at a young age may strengthen our immune systems and reduce our susceptibility to allergies. A recent study by the University of Chicago supports this hypothesis in its findings that exposure to microbial life on farms (a dirty environment) gave kids a natural resistance to asthma, allergies and other diseases. This suggests our increasing rates of asthma and allergies may be related in part to our lifestyles being too clean.

Another growing area of health concern is super bugs, the emergence of antibiotic resistant bacteria due to overuse of antibiotics in humans and in livestock, as well as the proliferation of antibacterial soaps and sanitizers. One of the most notorious is Methicillin-resistant Staphylococcus aureus (MRSA) infections caused by a type of staph bacteria that has become resistant to commonly used antibiotics. This is an area of particular concern in health care and nursing home facilities.

How can we apply this evolving science to building design and operation? We can start with a basic understanding of biodiversity. Without the regular application of chemical herbicides, the monoculture of a lawn can be quickly overrun with dandelions. By contrast, in a healthy forest we rarely see any one species of plant dominating the landscape because the diversity of species and their interdependence keeps the whole system in balance. The microbiome is no different. In a typical sealed building, air is recirculated and janitorial practices often focus on hyper-sanitization, so that when pathogens are introduced (through coughs, sneezes, etc.), there is little to resist their spread. Like the forest, a diversity of micro flora and fauna may prevent any one organism, especially harmful bacteria, from proliferating and increasing the risk of infection.

A recent study by the BioBE inventoried the biogeopraphy in dust within a LEED-certified building on the University of Oregon campus in Eugene, Ore., with some spaces having only mechanical ventilation and others with mixed-mode, natural and mechanical ventilation. The mechanical-only spaces were found to contain higher concentrations of potential pathogens and lower diversities of organisms, while spaces with operable windows experienced the opposite. Not surprisingly, microbes common to outdoor environments were present in greater numbers in spaces with operable windows, apparently helping to keep other microbe populations in check.

Another experiment looked at the impact of daylight on bacterial diversity in dust. It found that dark spaces had greater concentrations of bacteria, while light exposure led to lower concentrations, but greater diversity of organisms. More research is needed to draw firm conclusions to guide design recommendations, but these results reinforce what we already know intuitively: that is, buildings with plentiful daylight and operable windows tend to be better for our health. In addition to designing for healthy microbiomes, now we can also introduce a blend of helpful microbes into our buildings as a form of probiotic cleaning to reduce and control pathogen bacteria better than chemical cleaning regimens. Companies like BetterAir, Hollywood, Fla., are working with researchers to pioneer this approach.

While regular hand washing and building cleanliness upkeep are still recommended, we should nevertheless rethink our approach to creating and maintaining a healthy built environment based on recent discoveries about the rich and diverse microscopic world around us. Some examples of steps in the right direction include designing our cites with natural areas and gardens so that kids can get outside and get dirty, letting the outside into our buildings (including micro organisms), and dialing back the use of anti-bacterial products. To do this effectively, we need research to better understand how to design and operate buildings in a way that supports a beneficial microbiome while limiting the potential for harmful microbes. Perhaps your next project team might include a microbiologist along with the typical crew of engineers.


Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect with nearly 30 years of experience in sustainable building design. He is a director with YR&G Sustainability in Portland, Ore. To learn more, visit and follow Scott on Twitter @alanscott_faia.