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“Sustainability” is a commonly used words today. The concept of sustainability is relatively new; it was only recently introduced politically in 1987 but its impact cannot be underestimated. It has become a main focus in the engineering field and it has a direct impact on many countries’ policies.
There is no universally agreement on what sustainability means or how it is achieved, for each country has its own uniqueness and naturally its own way to sustain itself. This article will attempt to define the word and provide reasons for the emphasis of sustainability.
Rome is the city that will be analyzed in this article due to its fascinating history and approach to sustainability. How can an idea as new as sustainability be incorporated into Rome, an almost 3,000 years old city? And it seems that the city is doing well in terms of sustainability, for Tom Rankin, an architect in Rome, claims Rome to be Europe’s most sustainable capital (Rankin, 2015). This article serves to analyze the validity of Rankin’s claim, using Basilica of San Clement as an example because the construction of the basilica represents the common sustainable practice in Rome very well.
What is Sustainability?
United Nations World Commission on Environment and Development (WECD) broadly defines sustainability as “meeting the needs of the present generation without compromising the ability of future generations to meet their own needs” (Our Common Future, 1987). More specifically, sustainability can be focused on the environmental, social and economical aspect (Sustainability Briefings, 2013) (Figure 1).
|Figure 1. Triple Bottom Line – Sustainability consists of Economic, Environmental and Social Aspect
Protecting the environment is part of being sustainable, for the environment affects the health and lifestyle of the current and the future generations.
According to The Natural Step, the environment can be protected by following these steps:
1) “We cannot dig stuff up from the Earth at a rate faster than it naturally returns and replenishes” (The Natural Step, 2015)
Our goal is to make sure that we do not consume more than nature can produce. If we consume more or faster than nature can produce, resources will eventually run out. This especially applies to non-renewable resources, such as fossil fuels.
2) “We cannot make chemical stuff at a rate faster than it takes nature to break it down” (The Natural Step, 2015)Humans are continuously creating more pollution and damage to the environment. We produce carbon dioxide when we breath, for instance. It is true that we will always produce waste. However, we can help protect the natural laws by limiting the damage we create whenever possible. An example is to use less automobiles to lower the emission of greenhouse gasses.
3) “We cannot cause destruction to the planet at a rate faster than it takes for regrow” (The Natural Step, 2015)An example is deforestation. By creating excessive physical damage to the environment, humans can damage the ecosystem. We must damage the environment less than it can handled, or at least cure the environment after it is damaged. In the deforestation example, we can replant the trees after deforestation to help nature recover. Notice that even after we replant the trees, it will take a long period of time until the environment fully recovers to its state prior to deforestation. This is why we should try to limit degradation by physical means; nature may take a while to recover and it may not return to its initial state.
In term of protecting the environment, a role model we humans can look up to is cherry tree. Cherry trees help the environment by consuming carbon dioxide, a greenhouse gas, and producing oxygen. Also, they produce thousands of blossoms every spring to reproduce. Cherry trees do good to the environment because they help reduce greenhouse gases and create little to no waste (McDonough and Braungart, 2002). Another role model is ant. Ants do good to the natural laws overall. The biomass of ants on this earth is more than that of humans yet ants do not damage the earth as much as humans do (McDonough and Braungart). They eat decaying organic matter, aerate the soil, can be used for medicine and many others that benefit the environment (McDonough and Braungart). Humans, on the other hand, create more damage than good to the environment. Humans use more natural resources than needed to survive, produce wastes that do not completely integrate back to nature and worst of all, we change nature. To be sustainable, we must take actions to create less harm to the environment. Protecting the environment is the right thing to do, for the current and the future generations.
Sustainability also means satisfying quality of life, for the current and the future generations. Just like The Natural Step lists, ” we cannot do things that cause others to not able to fulfill their basic needs” (The Natural Step, 2015). There are a lot of people on this planet and we are all striving to improve our quality of life (Figure 2).
|Figure 2. Current World Population and U.S. Population
The concept of sustainability in building infrastructures is increasingly enforced in engineering because engineers can have a direct impact on sustainability through design, construction, operation, maintenance, and demolition. Thus, engineers can have an impact on the environment as well as the quality of life for the individuals.
Sustainable practices help protect the environment, ensure the quality of life for individuals and at the same time have to be financially affordable. If sustainable practices are expensive, there would be less incentives to be sustainable. It turns out that sustainable practices can be affordable and even cheaper than less sustainable practices.
” We believe green buildings are not only good for the environment, they also provide immediate and long-term economic benefits for developers, building owners and occupants.”
– Turner Construction
In Roman and modern engineering, integrating sustainability into building practices is cost efficient. Such example can be seen in Basilica of San Clement in Rome, Italy.
Background: Basilica of San Clement
Basilica of San Clement, built in 1123, is a Roman Catholic Church located 300 yards north of the Colosseum (Sacred Destination, 2015) (Figure 3). Today, it is one of the most famous basilicas in Rome, Italy, not only because of its richly adorned interior with golden mosaic apse and gold- decorated ceiling, but also its availability for tourists to explore the multiple layers of history beneath (Sacred Destination, 2015) (Figure 4).
The Basilica of San Clement was built upon old structures and the bottom layers were not rediscovered and excavated until the beginning of the 19th century (Sacred Destination, 2015). The layer below the present Basilica of San Clement is a 4th century Dark Ages Church decorated with frescoes (Sacred Destination, 2015)(Figure 5, 6,7). It was destructed the Normans in 1804 and was structurally unsafe, thus the 12th century basilica was built above (Sacred Destination, 2015). This layer is now filled in with rubble to support the 12th century basilica above. During the excavation, the archaeologists exposed parts of the columns to let visitors see the structures of the ancient church (Figure 8).
The layer below the 5th century basilica lays a first century house and a Mithraic temple, separated by a narrow isle (Sacred Destinations 2015) (Figure 9). The 4th century church was built upon this layer many years after the buildings were destroyed in the fire of Nero in 64 A.D. (Sacred Destinations, 2015) Similar to the second layer, this layer was filled in and used as foundations for the structures above it.
How is Basilica of San Clement Sustainable?
The construction of Basilica of San Clement is sustainable because it reuses existing building components. The structures in the second and third layer are reused as foundations for the 12th century basilica above. The difference in columns is another example. The columns have different design: Ionic and Corinthian order and they are made of different materials: Proconnesian, marble, cipollino, granite and gray-veined marble (Barclay Lloyd, 2005) (Figure 12,13,14). Similarly, the tiles on the floor are of different colors and materials (Figure 11). The difference in columns and floor tiles suggests that they do not originate from the same locations; the builders who built the new Basilica of St. Clement used materials that they found nearby to build the new basilica. Reuse of building components is a sustainable practice. It satisfies the environmental,social and economic aspects of sustainability.
Basilica of San Clement is environmentally sustainable because it was constructed by reusing materials and structures from its surroundings. Some columns and tiles, for example,were reused from existing buildings and thus reduced the need to harvest new materials when building the 12th century basilica. Lessening the harvest of new materials satisfies laws of Natural Step, which are to limit resource extraction from the earth’s crust and to limit physical damage to the earth (Natural Step).
Using the foundations of the structures below and creating layers of structures in Basilica of San Clement is an example of social sustainability because it helped preserve history. When building Basilica of San Clement, the 4th century church, Mithratic Temple and the Roman house could be destroyed. Instead, the 12th century basilica was built on top and thus preserving the existing structures. This is socially sustainable because it allowed generations after the construction to be able to explore and gain insight into centuries of history beneath Basilica of San Clement. By looking at the frescoes and mosaics underneath, visitors can learn more about religion and culture back in the 4th century and 1st century (Sacred Destinations, 2015).
Although reusing materials and structures aid the environment and help preserve history, the builders did not reuse for those intentions when constructing Basilica of San Clement . The reuse of materials and structures was mainly driven by economic reasons; it was more financially reasonable to reuse and build on top of structures than to tear down existing buildings and getting new materials.
Construction cost is less when reusing existing building materials. Instead of purchasing new materials, builders instead identify components that may be directly used onsite. If a new building is to be constructed on the site of an existing structure, an alternative and more cost effective approach is to consider how the old structural components could be integrated or reused in the new structure. In other words, instead of designing a structure and obtaining the materials, builders and engineers can identify reusable components first and then develop a design to make use of them. This was the construction process of Basilica of San Clement and it is economically sustainable and practical (Building San Clement). It saved construction cost by purchasing and transporting less materials. The more the builders reused, the cheaper the construction.
The practice of reusing became common because existing, underused building components were easily accessible. During and after the Roman Empire, the population of Rome decreased dramatically, from 1.5 million people during the peak of the empire to only about 30,000 people within the next several centuries (Figure) . Since the population decreased drastically, many of the buildings were vacant and it was logical and financially accessible to use existing building materials nearby to build structures instead of harvesting new materials to build completely new structures. This shows that Romans were the most inventive during tough times when money was tight and they were looking for the most cost efficient method to build buildings (Tom Rankin, 2015).
The layers created at Basilica of San Clement was also driven by economic reasons. When building the 12th century basilica above, the structures beneath were preserved mainly because it was costly to demolish them, not because the builders wanted to save the layers beneath for future generations (Building San Clemente). It was more cost efficient to fill in the structures beneath and build layers above another.
Comparison of Roman Sustainability to Modern Day Sustainability
Analyzing Basilica of San Clement is a great way to study the sustainability of building infrastructures in Rome. This is because the reuse of materials and existing buildings components, just like in the construction of Basilica of San Clement, is a common practice in Rome and the basilica is one of the few still standing structures that allow visitors to explore the layers beneath. There are many examples in Rome where existing building components are reused .Some examples include Theatre of Marcellus being used as a facade for Roman apartments and Piazza Navona built on the remains of Domitian’s Stadium (Figure 15). The practice is common in Rome because the quantity of new construction is so outnumbered by the quantity of existing buildings. It is financially practical and beneficial to perform the sustainable practice of reusing, thus making Rome stand out as a sustainable city.
|Figure 15. A picture of Theatre of Marcellus(Photo by Author)
There are some similarities between sustainability in Roman building infrastructure and modern sustainability. Just like how Basilica of San Clement has layers of structures, modern buildings, especially in urban settings, tend to be high rise buildings. This is because layering is a great sustainable solution to population growth and scarcity of land. Tall buildings or layering can fit more people in limited land. At the same time, urban synergies and efficiency are maximized by design and can reduce waste to almost zero, thus being environmentally sustainable (Rankin, 2011). It is incredible that the Romans had the sustainable practice of creating layers of structures centuries ago and the practice is still used today in modern engineering.
Besides the layering effect, adaptive reuse of existing buildings is used in both Roman and modern engineering. Reuse is seen in Basilica of San Clement and all over Rome, where there is an abundant of old, under utilized buildings. The building components from Ancient Rome were used during the fall of the Roman Empire and are still continually used today. This is because Rome is constantly growing in population in recent years and the demand for usable building components increases. People in Rome can harvest new materials in addition to using existing structures. Similar practice can be seen in modern engineering. An example includes Portland, Oregon’s “511 Building“, which was a post office that is currently reused as the Pacific Northwest College of Art. Again, Roman engineering from centuries ago is still applied to modern engineering. This shows the brilliance and practicality of Roman engineering.
Although there are some similarities between Roman and modern engineering, there are some differences. The dominant reason behind adaptive reuse in Roman building infrastructures is money. Protecting the environment was not a priority. On the other hand, sustainable practices in modern engineering are driven by environmental, political and economical reasons.The environment is a driving factor in sustainability in modern buildings due to global warming, decrease in natural resources and other man-made environmental issues, which leads to political enforcement in sustainable practices in buildings in some areas. For example, in Washington State, USA, all new buildings and renovations that receive state funding must be LEED certified.
Even though the environment and politics play a role in encouraging sustainable practices, economy is still the main factor. Reusing building components is more cost effective than building buildings from the beginning; less new building materials need to be purchased. At the same time, reusing components and materials reduces the energy and labor to inspect the materials, process them, deliver them and incorporate them in the construction. Although some energy are required, they are still less compared to building completely new structures.The material already in an existing building represents between 10 and 20 percent of the lifetime energy of that building (Sustainability Briefing, 2013). Retaining structural framing while replacing building systems can produce a building that performs as well as a new building while preserving much of the embodied energy of the old building. (Wiley Series in Sustainable Design: Sustainable Renovation: Strategies for Commercial Building Systems and Envelop). It turns out that the more sustainable practice also makes the more economic and practical sense; it was true in Roman engineering and it is still true in modern engineering. The main difference is that economy is not the sole driven factor for sustainable practices in modern engineering. Politics and environment are main factors as well.
Roman engineering was efficient with adaptive reuse and was sustainable. But in modern engineering practices, the word “renewable energy” often comes into mind when discussing sustainability. According to LEED, building sustainability includes reduction in addition of new material through reuse of existing building fabric and reduction in ongoing operation energy and waste through development of efficient building systems (LEED, 2015). Roman engineers were sustainable at the construction phase of the building, but not as much during the maintenance phase. The sustainability in the maintenance phase in modern engineering suggests the use of renewable energy such as solar power because it is more environmentally sustainable by reducing operation energy and waste. Roman engineering did not use renewable energy because technology such as solar panels were not available at the time; Roman engineers used what was available to them and used it well.
Another difference between Roman and modern engineering is the safety enforcement. It is crucial that the building is structural safe. One of the challenges reusing structural components include the structural stability of the building (Sustainability Briefings, 2013). In other words, reusing existing building components can be unsafe because the component may not be strong enough to be reused in new construction. This is why current United Kingdom and European Union legislation tends to place more emphasis on the recycling of materials rather than component reuse (Sustainability Briefings , 2013). However, if building components are to be reused, extensive research will be conducted on the reused and recycled materials before using them in new constructions to ensure that the components will not fail (Sustainability Briefings, 2013). Modern engineering is more cautious while reusing and puts more safety precautions to ensure the building does not fail structurally. Roman engineers still did a wonderful job with adaptive reuse;
Basilica of San Clement has been standing since the 12th century. This shows the brilliance of Roman engineering.
Overall, Roman engineering, as seen in Basilica of San Clement, is sustainable through adaptive reuse of existing building fabric. The practice is economically beneficial and is still used in modern engineering. Just as Carl Elefante said, “the most sustainable building is the one already built” (Rankin, 2015).
“Sacred Destinations.” San Clemente. N.p., n.d. Web. 30 Sept. 2015.
“Sustainability Briefings.” (2013): n. pag. Institution of Structural Engineers, 2013. Web. 30 Sept. 2015.
“The Natural Step (TNS) Has Been a World Leader in Strategic Sustainable Development for over 25 Years.” The Natural Step. N.p., n.d. Web. 30 Sept. 2015.
Rankin, Tom. “Still Sustainable City Blog: ROME.” Still Sustainable City Blog ROME. N.p., 25 July 2015. Web. 30 Sept. 2015.