Green, Sustainable Structures: Look Underground
Gary S. Brierley and Russell L. Jernigan — Dec 01, 2009
In L. Frank Baum’s book, The Wonderful Wizard of Oz, the Emerald City’s walls are green, but the city itself is not. Everyone in the Emerald City is made to wear green-tinted eyeglasses, making things appear green. Just another “humbug” created by the Wizard, who, as we now know, was a Wizard of Spin, not of actual magic.
Much of the hue and cry around “green” and “sustainable” construction feel like we’re being asked to don green glasses. In the rush for sound-bites, we may well be promoting a spin wizard’s “humbug” over actual sustainability. And yet, even with all the tooting of horns, there is a distinct shift developing from green-seeming to a truly sustainable ethos, and to the realization that the brilliant city needs more than green glasses.
In the popular press, it would seem that this rush to greenness is a new phenomenon, but tunnel engineers have been writing about environmental and sustainable concerns for decades. So it is with bemusement that we read about this “new global concern,” when, in fact, the greenest and most sustainable structures of all are right where they have always been: beneath our feet.
The use of the underground, from infrastructure to living quarters, is an ancient concept. Even Neanderthals came by the “cave man” moniker honestly. Tunnels don’t disturb surface activities such as farming or traffic, and that’s a plus. Tunnels are also less vulnerable to the weather, earthquakes and terrorism. One of the first aqueducts in Rome was built entirely underground for security reasons. For instance, the Aqua Virgo remained flowing when other aqueducts were destroyed during the Goth invasion of Rome and still flows today as the Aqua Vergine. There are qanats still transporting water after a thousand years in the Mideast. Cliff dwellers in the Southwest understood the insulating as well as the structural benefits of using the earth for housing.
The surface of our planet is an increasingly crowded space. It has been suggested that one of the chief contributors to global warming is the loss of natural cover. It is also becoming increasingly obvious that the earth needs large amounts of open space to renew its natural systems, and that human beings must begin to limit their impact on the planet. Until now those interested in preserving the surface of the earth as the domain of plants and animals had no reason to consider the future with anything but a gloomy, rearguard fatalism.
The environmentalist utopia is a planet devoted entirely to those functions that only the surface can perform: farms, homes, parks, gardens, commons, arboretums, conservatories, preserves, reservations, and wilderness. When you mention underground space or tunnels, most people think of large transportation projects such as subways, the Chunnel, or highway tunnels. They likely completely overlook parking garages and pedestrian underpasses, and have no clue about the maze of underground conduits facilitating everything from water in and waste out to phone and electrical cables.
What Are “Green” and “Sustainable”?
As the fervor for “green engineering” and “sustainable construction” approaches apocalyptic momentum, its ideology has passed from the realm of wish list extras to essential project features. More government entities are using a mix of mandates and incentives to push for greener buildings in both the public and private sectors. But what does it mean, in legal and contractual terms, to be “green”?
Though green building is interpreted in many different ways, a common view is that they should be designed and operated to reduce the overall impact on the built environment, human health and nature, from efficient use of resources to reduction of waste, pollution, and environmental degradation across the building’s life cycle. According to the U.S. EPA, “Green engineering is the design, commercialization, and use of processes and products, which are feasible and economical while minimizing 1) generation of pollution at the source and 2) risk to human health and the environment. Green engineering embraces the concept that decisions to protect human health and the environment can have the greatest impact and cost effectiveness when applied early to the design and development phase of a process or product.”
Green construction is not just a name, it is in fact a standard developed and maintained by the U.S. Green Building Council referred to as LEED certification. The main advantages of a LEED certification are:
- Lower operating cost and increased asset value
- Energy and water conservation
- Landfill waste and greenhouse gas reduction
- Healthier and safer environment for tenants
“Sustainable engineering,” by definition, takes the long view with “a set of environmental, economic, and social conditions in which all of society has the capacity and opportunity to maintain and improve its quality of life indefinitely ... without degrading the quantity, quality, or the availability of natural resources and ecosystems. … Sustainable civil engineering improves the quality of life today and in the future by improving infrastructure and the built and natural environments. Sustainable civil engineering also minimizes environmental impact by reducing the rates of consumptions of renewable and nonrenewable resources and the rate of generation of manmade wastes to or below the rates of the earth’s natural carrying capacity.” ASCE’s Task Committee on Sustainable Design believes that as the acknowledged stewards of the built environment, civil engineers must lead the way in planning, designing, and constructing sustainable infrastructure.
Sustainable development uses concepts such as resource conservation, waste minimization, and life-cycle costing in an effort to obtain acceptable economic activity combined with manageable environmental impact. Its vision is to facilitate not just growth, but growth that results from long-term, life-sustaining economic activity — financial and environmental.
From utilities to human space, development has already started to “burrow.” Moving transportation arteries to the basement is an old concept. Cities such as Montreal, Kansas City, and Houston are already ducking under their weather and traffic in an organic underground expansion of commercial and work space — imagine the conservation of design and life-cycle resources when such spaces, now that their viability and desirability has been proven and is gaining market-driven momentum, are specifically designed as a single integrated vision. Egress control aids issues like security, air quality, and insulation. Underground space can be constructed precisely where it is needed most, without causing massive disruption during construction and without taking valuable surface area out of circulation.
Underground development has already proven itself “earth friendly” during the construction phase: surface disruption is limited to very controllable access shafts and construction methods must meet or exceed all current federal, state, and local regulations and codes. Removed material is essentially the earth’s own, and can be recycled into other building projects.
Frankly, the interior of a modern office sky-rise is as isolated from the outside world as anything underground. Problems such as ventilation, lighting, and other utilities are comparable. However, underground, seasonal and diurnal temperature differentials that every above-ground structure must contend with are moot. Users of Montreal’s “Underground” (some 500,000 people daily) describe shirt-sleeve conditions in midwinter. Vintners have known for generations the efficacy of wine caves. The energy to either heat or cool an underground space is a fraction of the cost for a similar volume of above-ground space. Further, underground facilities provide unique and cost-effective opportunities to create highly controlled temperature, dust, and vibration environments for sensitive manufacturing or research activities.
Underground structures also do not require resource redundancy to be self-supporting. Recent improvement in lining design for below-ground structures has demonstrated conclusively that the ground is as available to resist load as it is to impose it, and that the ground can actually be incorporated into the structure in many cases. Hence, much thinner and less costly, but still very stable, structures can be provided by utilizing the local geology.
Buried infrastructure, pipelines, etc., once below the temperature and surface noise (vibration and disruption) thresholds, short of dramatic geologic events, lie quiescent. In the case of moving water — a serious concern in arid regions — open canals and irrigation can lose up to 60 percent, by some accounts, through evaporation, leakage, and other causes. Run the same flow underground, and even leakage is minimized if not eliminated.
In some cases, such as Austin, Texas’ Clean Water Program (ACWP), the use of underground solutions was in direct response to an EPA-issued administrative order. In the course of over 100 wastewater improvement projects, about 190 miles of sewer lines have been installed to date, and a sizeable percentage of those were installed — as the most resource- and cost-effective solution for those alignments — using trenchless technology. The amount of wastewater discharge from the collection system and the number of sewage overflows citywide have dropped dramatically as a result.
Don’t Sing Those Dollar Sign Blues
Of course, the resource demanding the most conservation for any project is money and underground projects have been seen as too costly, at least at the outset. But this is an increasingly inaccurate argument.
A few years ago the happy winner of an annual civil engineering award regaled the audience with the tale of his project, the design of a high-security facility for the government. First the speaker listed the specs: the facility had to be able to withstand a direct impact from a big tornado, shrug off a crashing airplane, and be impervious to terrorist attack. Nothing surprising. The engineer then described his solutions: concrete walls 4 ft thick, layers of reinforcing steel, and so on. The eyes of every tunnel professional in the room began to glaze; this happy fellow was boasting about spending tens of millions of client dollars just to replicate on the surface everything that was readily available under his feet. Indeed, the use of underground space for secure storage is well employed. From NORAD’s Cheyenne Mountain to underground vaults, both reclaimed and specifically excavated underground spaces, fit the bill.
But the value of green/sustainable buildings is not measured just by its cost to build. The project’s life cycle must also be taken into account. We’ve already noted underground water systems still functioning hundreds of years past their final amortization. There are subway lines functioning perfectly reliably through bores driven more than 100 years ago. London’s Greenwich foot tunnel, opened in 1902, was still a lovely stroll in 1991 when one of the authors used it to cross under the Thames.
Demand drives supply and innovation. As the near-surface utility network becomes more dense, the urban surface area becomes more valuable. The cost of disruption skyrockets — in both economic and sociological terms — rendering tunneling not only more satisfactory but also less costly as compared to various at-grade or cut-and-cover options for infrastructure improvement. In the case of another Austin project, the trenchless installation of a wastewater line was the only option that could be agreed upon by all stakeholders. And it was completed at a conservative cost, as well as three months earlier than the surface-based solution would have finished.
Writer Fred Hapgood relates a conversation with Ray Sterling, then director of the Underground Space Center at the University of Minnesota and a co-author of Underground Space Design: “European authorities tell me,” Sterling said, “the public tolerance for putting things on the surface has fallen so low that increasingly the test of whether something gets built at all is whether it can be put underground.” Hapgood further notes that Sterling spoke to him from an office seven stories beneath the Minnesota winter.
Older than dirt, the territory beneath our feet patiently awaits: quiet, earthquake-resistant, weatherproof, secure, energy-efficient, with virtually no constraints of geometry, scale, or location. And, through careful design, construction, and maintenance, underground space is more than compatible with conservationist and preservationist values, no matter how strictly construed.
No, you don’t need green-tinted glasses to see the brilliance of underground development. The marvelous land of green and sustainable development is right below our feet. Even the Wizard of Oz would have been impressed!
References:
Bruce Buckley; Eco-Design Risks: The Gray in Green; Green Source; 07/2009.
Albert Grant, P.E., F.ASCE and Craig Farkos, P.E., M.ASCE; “ Task Committee on Sustainable Design Outline Strategy”; ASCE News; 10/2009.
Gary Brierley and Joe Guertin; “Subsurfing USA”; World Tunneling; 03/1998.
Fred Hapgood; “Notes from the Underground”; Atlantic Monthly; 08/1994 and “The Underground City”; US Airways Attache´; 03/1998.
Gary Brierley, Kent A. Pease, and Ronald D. Drake; WT FOCUS: “Urban Underground Space Frontier”; World Tunneling; 11/1992.
Gary S. Brierley, Ph.D., P.E., is President and CEO, Brierley Associates, LLC, Denver. Russell L. Jernigan, Ph.D., P.E., PG., is a Partner with Brierley Associates, LLC, based in Austin, Texas.
