The idea of "green buildings" has been rapidly growing around the world since the 1970s due to the energy crisis. Today, green building projects make up about 50% of new construction projects (Green 2015). When people hear the words green building they think of projects that focus on new technology and building techniques to reduce energy consumption and are a modern architectural design. An alternative in green building design that is not thought of as often is called adaptive reuse. This refers to the reuse of a building or site for a purpose that it was not designed for originally. It is often more environmentally friendly to retrofit an old building than to build a new "green" building. According to "The Greenest Building: Quantifying the Environmental Value of Building Reuse", it can take 10 to 80 years for a new energy efficient building to counteract the negative environmental ‍impacts ‍of constructing it (The Greenest 2011). Although the concept and popularity of green buildings is a relatively new idea, the Romans have been using this technique of adaptive reuse for centuries. Examples of this can be seen walking down most streets in Rome where you'll see everything from old columns left in the sides of buildings to buildings whose foundations are ancient ruins (see Figures 1 and 2 below). In this article, the main concepts of adaptive reuse will be discussed and applied to multiple sites in Rome. We will take a closer look at the Teatro Marcello, Castel Sant'Angelo, and the Basilica di San Clemente as examples of adaptive reuse in ‍Rome‍.

Figure 1: Column left in side of wall

Figure 2: Reuse of decorations

Adaptive Reuse

Adaptive reuse is the term used to describe the reuse of older buildings nearing the end of their life cycle that are renovated to serve a new tenant and purpose. Often these buildings have become obsolete or redundant due to changes in the culture of the area or to changing demand for their services (Yung 2014). This building method can be seen in many major cities today; reusing everything from old schoolhouses to old industrial sites. These sites are converted into housing complexes, art museums, hotels, office spaces, and retail stores - or anything that needs a new space. Adaptive reuse is often used as a way to preserve historic buildings so that they can continue to shape the community and receive the maintenance and upkeep they need so that they will be preserved for future generations. It can also help to revitalize old neighborhoods and bring revenue into poorer areas.

There are multiple types of adaptive reuse which correspond to how much of the building can be reused. The first type of reuse is when the above ground structure of the building is reusable. For this type of reuse the above ground structure must be in a good enough condition to be reused and the interior and exterior geometry of the building must be functional for the new use or can be easily expanded upon to accommodate the new purpose. The materials of the building must also be able to sustain the new loads that would be placed on it during construction or due to the new tenants requirements. The second type is when the basement can be reused. The space and layout of the basement and its load bearing capacity must be able to accommodate the either the new above ground structure or the updated one. The third type of reuse is foundation reuse. Reusing the foundation comes with multiple problems but is necessary if any of the building is to be reused. If the above ground structure and the basement have to be replaced then the foundation would undergo unloading and reloading which could cause additional settlement of the foundation because of soil relaxation. If the new loads on the foundation are not greater than the previous load then the foundation can be reused (Laefer 2008). Depending on which parts of the building are fit to be reused, one of the three different scenarios for reuse can be used. The first situation is one where only the foundation can be reused if the above ground structure and the basement are deemed unfit to be reused. The second is if only the above ground structure cannot be reused but the foundation and basement can be. The third is if all three parts of the structure can be reused. The third option is the best as it saves the most money and has the least environmental impact but is also the hardest to do as all parts of the building must be able to meet all of the requirements for reuse. Even though total reuse is the most desirable option, any reuse is beneficial as it reduces the cost and environmental impact of the project when compared to new construction.

Benefits of Adaptive Reuse

The main benefits of adaptive reuse are related to ‍energy use and emissions reductions, cost savings, a faster construction schedule, and decreased liability exposure. Material transport to new construction project sites uses a lot of energy, time and money. Disposing of materials from demolition uses a lot of energy and space in landfills. By avoiding demolition, removal, and reconstruction of an old building there is less energy used and fewer materials sent to landfills (Laefer 2008). Labor costs go down because the work related to demolition, reconstruction, material transport, and waste disposal is reduced. Material costs go down as well as far less materials are required to restore an older building than to rebuild one from scratch. When the foundation is reused, large excavation costs are saved through labor, equipment, soil transport, and waste removal costs. Foundation reuse also allows for improved constructibility and soil performance. Crowded subsurface conditions can make foundation installation difficult and costly. The problem of clay-heaving (see Figure 3) and settlement from removal and reinstallation of the foundation and basement of the building are reduced or eliminated. Foundation reuse also avoids the need for excavation support which can damage adjacent buildings.

Clay Heave.jpg
Figure 3: Clay-heaving and lateral expansion due to foundation removal

Foundation reuse also avoids problems related to lowered foundation capacity due to foundation removal. Less utility relocation will be necessary which typically requires a great deal of coordination and time. This minimizes service interruptions as well as saving time and money. There are also indirect cost savings from a shortened schedule length. When the schedule length is shortened the chance for delays, accidents, and liabilities is reduced. Noise pollution in the area due to construction is also reduced (Laefer 2008).

One of the largest and most comprehensive studies done on adaptive reuse of buildings is "The Greenest Building: Quantifying the Environmental Value of Building Reuse" done by the Preservation Green Lab and other contributors. Six different types of buildings including single-family residential, multi-family residential, urban village mixed-use, commercial office building, elementary schools, and a warehouse conversion were analyzed using ‍Life Cycle Assessment (LCA). ‍LCA is a widely used method of evaluating the environmental and human health impacts associated with products and services throughout their life time. LCA considers the life cycle to happen in a series of steps starting with extraction of raw materials and ending with demolition and disposal of materials. The study examined four different categories of environmental impact which included climate change, human health, ecosystem quality, and resource depletion. The study found that building reuse almost always creates fewer environmental impacts than new construction when comparing buildings of similar size and functionality. The amount of environmental savings from building reuse varied widely based on the type of building, location, and assumed energy efficiency. Most all of the building types tested showed environmental ‍savings ‍about 4-46% higher for reused buildings over new construction of similar size and functionality over a 75-year period. The warehouse to multifamily residential type was the exception in that there were actually lower environmental savings when compared to new construction. The warehouse conversion had a 1-6% greater environmental impact. This is attributed to multiple factors, the most prominent being the type and amount of materials used in its reconstruction. This study showed that the repurposed buildings had greater immediate environmental savings than new construction. It also showed that new construction had a great initial negative environmental impact but due to its higher energy efficiency closes the gap between it and the repurposed building so that they will reach a point they call the "year of carbon equivalency". The average time for the environmental impact to equalize was about 42 years (The Greenest 2011).

In a case study comparing adaptability, three different historic buildings in the San Francisco area were investigated in detail to showcase how effective adaptive reuse can have positive impacts on sustainability and building life span. The three buildings that were evaluated were the International Center to End Violence, the Walt Disney Family Museum, and the Presidio 101 and 103 buildings. All of the projects were located in the Presidio of San Francisco, a large national park located at the southern end of the Golden Gate Bridge. The location of these buildings presented a design difficulty in upgrading the ‍earthquake ‍performance of the buildings while maintaining their existing appearance, as San Francisco is an area of high seismic activity. Each building had an updated lateral system and new architectural design for the interior of the building. They were then evaluated using building LCA. All three of the buildings were found to result in a decrease in the global warming potential of the energy in the structural ‍system over a life span of 50-years ‍(Maclise 2013).

Issues with Adaptive Reuse

In most studies relating to adaptive reuse and sustainability, reuse was deemed the more environmentally friendly alternative to new construction. Even though this method is preferable because of cost impacts and environmental impacts, there are a few issues that cause developers to not want to use this method. The first is that in urban areas there is a large financial incentive to maximize the use of space on a site. The developer would want to build as high and as close to the property line as possible so that they could make the most of the space while building an impressive high rise building. This causes developers to often look for developable land instead of buildings to retrofit. Another issue is that the environmental costs associated with the construction and demolition are external to the developer which gives them incentive to demolish and rebuild since they cannot directly reap the cost benefits. Often, retrofitting is seen to have much more risk than new construction. This is because it can be less predictable and more susceptible to unforeseen challenges once the project in underway‍. Building codes and regulations are a large barrier to retrofitting‍. Codes often favor new construction and do not adapt well to the unique situations presented by building reuse. Finally, the existing building simply may not be able to accommodate the function of the new building or fit into the context of the neighborhood (The Greenest 2011). With cities evolving, new construction will always be necessary.

History of Adaptive Reuse in Rome

Even though the term adaptive reuse is relatively new in today's engineering and architectural professions, the Romans have been reusing materials and repurposing old buildings for the past 2000 years. It started in the late republic of Rome (123 to 23 BC) when selling materials from old buildings was a popular business (Jacks 2008). At first this was a large problem for preservation of these older buildings as many of them were being demolished so that the materials could be reused and sold. There were multiple laws enacted to try and stop this sort of trade. The first was in 44 AD by Hosidianus and Volusianus, followed by Vespasian between 69-79, and finally by Alexander Severus in 222. None of these laws seemed to stop people from reusing and selling materials from old buildings as we can see today by looking at ancient buildings around Rome. Even Alexander Severus who had passed laws regulating the trade restored the Porticus Octaviae by reusing column shafts and entablatures of Pentelic marble (Jacks 2008). He was not the only emperor to reuse materials when they were building a new monument or building. Commodus updated the Colossus of Nero to resemble himself as the sun god Helios. Constantine's triumphal arch (Figure 4), dedicated in 315, is full of reused pieces from earlier monuments. The reused decorations include reliefs of Marcus Aurelius (with the faces replaced with that of Constantine) on the attic, reliefs of Trajan in the passageway of the arch, roundels of Hadrian on the face of the arch, and the columns, capitals, and architraves. The reuse of these decorations was seen to be a way of solidifying Constantine's power over Rome by setting himself equal to great leaders of the past.

Figure 4: Arch of Constantine

In 379 when Theodosius became the emperor of Rome, the official state religion was changed to Christianity. They took away the responsibility of the prefects to upkeep the ancient temples in the city as they no longer served a purpose as a public building. They needed to either demolish or repurpose the pagan buildings to solidify Rome as a Christian state. In 458, a judicial order required Roman citizens to remove any ornamentation from ruined buildings to be reused for public projects. This mass removal stopped just short of destruction of these buildings as they could be reused for Christian worship. This law and the repurposing of these buildings is what saved them from being completely lost. In many areas of the Roman Empire, clerics saw the need to rid pagan cult sites of their demons. This meant rededicating pagan sites to figures in Christianity by covering up old art work and adding new images among other things. The approach was a little different in Rome. The Popes decided to focus more on the Roman Forum as it was full of imperial and 'profane' buildings. The former audience hall and adjoining library were turned into the church of Santi Cosma e Damiano. The Curis Senates was rededicated to Sant'Adriano. The ‍Pantheon ‍was the first of many Roman temples that were officially converted into a Christian church when it was dedicated to S Maria ad Omnes Martyres in 609. The images on the attic of the Pantheon were removed. In the Figure 5 below, the holes in the facing of the attic show ‍‍where sculptures and reliefs that were removed would have been.

Figure 5: Facade of the Pantheon

This is seen around most of the ruins and ancient buildings in Rome which shows us how widespread the repurposing of buildings was during this time period.

The San Nicola church in Carcere is another example of a temple that was repurposed into a church. It differs from the reuse of the Pantheon in that many parts were completely rebuilt instead of only changing the ornamentation on and inside the temple. The basilica of San Nicola was built over the ruins of three temples in the Forum Hoitorium. The fortified tower of the church was built partly over the podium of the northernmost temple and partially included the front columns of the middle temple. The architraves were shored into the wall with fieldstone and rubble and pier buttresses were added around the inner chamber of the ancient temple. On the south side of the church Doric columns from the southernmost temple were embedded in the wall of the church and used to support beams in this side of the church.

During the Renaissance, architects studied those temples to learn more about Vitruvius' ‍writings and the building methods used in ancient Rome while disregarding the additions to the temples during the Christian repurposing. Also during this period, many families wanted to reuse antiquities as it boosted their status through showing their Roman lineage and to obtain territorial advantage.

Jumping forward to the 20th century, we see another period of reuse of ancient ruins in Rome when Italy was under Fascist leadership. The ruins were reused in an ideological way. Fascism wanted to connect itself with the grandeur of the Roman Empire. The ruins were used as the wings of parades for Mussolini and the main element in his idea of 'public use of history' (Federici 2011). The Master Plan for Mussolini's fascist Rome wanted to move the focus of the city away from the historic center and expand the city. His plan included building the EUR as the new city center, large avenues to create order in the city, and uncovering and restoring old ruins to show the triumphs of the Roman Empire.

Throughout Rome's long history of adaptive reuse it is evident that Romans were very logical in their methods of building. They reused buildings not for architectural purposes or to preserve the history. In most cases, it was easiest and cheapest to simply give the building a new function or to reuse materials from a building located very close to the new project as it was expensive to create and transport new materials. It was thus a logical decision to reuse. This is often why the most reuse projects were done during periods when Rome's financial situation was less than ideal.

We will now go into more detail with specific examples of adaptive reuse that can be seen in Rome. Below is a map showing the locations of these sites.

Teatro Marcello

One of the principal monuments of late Republic of Rome, the ‍Teatro Ma‍rcello, originally ordered to be built by Caesar, was dedicated by Augustus in 13 or 11 BC in memory of his late grandson Marcellus. The theatre was built on the site of an old theatre and temple building known as the ad Apollinis near the Tiber River. Though not all of the theatre can be seen today, it was a great example of the traditional Roman theatre that was based on the amphitheaters of ancient Greece. In contrast to the Greek theaters it was built on a substructure of arches and barrel vaults with decorative columns instead of into a hillside. The theatre consisted of three tiers of arches with an orchestra, semicircular seating area that ascended upward from the stage, and a large decorative wall backdrop for the stage (see Figure 6). The decorative columns on the outer facade of the theatre were Doric on the first level, Ionic on the second level, and most likely Corinthian on the top level. It can not be known for sure what type of columns were on the top level of the theatre since it has been replaced. Below is a video that shows the two levels of columns visible today as well as the medieval attic story.

teatro original.jpg
Figure 6: Reconstruction of the original Teatro Marcello

As can be seen from simply looking at the theatre today, it has a great history of reuse. The theatre stopped being used around 525 when travertine was taken from the theatre to restore the Ponte Sisto. It was repurposed as a fortress during the Middle Ages and later a palace of the Savelli family in the sixteenth century. Under the Savelli family's ownership the attic story that can be seen on top of the two levels of columns was built. At this time butcher's stalls occupied the ground floor and there were medieval homes that filled in around the interior cavae of the theatre. Today the attic story addition and other buildings that abut the ruins of the theatre house apartments for modern Romans. The site also holds concerts during the summer months. In an excavation project from 1926-1932, part of the exterior of the structure became visible again. The preservation of the original structure of the theatre can be accredited to its reuse throughout its lifespan (see Figure 7).

Figure 7: Facade of Theatro Marcello

During my visit to Rome the Teatro Marcello was one of my favorite sites around the city. It is quite different from most of the other monuments because of its eclectic aesthetic and very evident signs of reuse. It somewhat epitomizes the idea of reuse in Rome's history that I found so fascinating. If you are standing on the other side of the building than that shown in Figure 7 you would think that it is simply a set of apartments that look very similar to the rest seen around Rome, but then you turn the corner and you see ancient ruins building into the side of the building. It is also interesting from a structural point of view. You can see where the barrel vaults of the old theatre were filled in with concrete to allow for more support of the new structures that were added to it (see Figure 8). At the left end you can see multiple buttresses that were added around the same time as the attic story (see Figure 9).

Figure 8: Arches filled with concrete

Figure 9: Triangular supporting walls

The reuse of this site can be interpreted as a total reuse of the existing building with additions made to it to serve its new purpose. As the loading of the building changed due to its new additions structural supports had to be added which were mentioned earlier. This is similar to what would be done today when making additions to existing buildings.

Castel Sant'Angelo

The Castel Sant'Angelo, now a museum, started as the Mausoleo di Adriano and was later converted to a fortress and castle for the Popes. The Mausoleo di Adriano was built by Hadrian for use by himself, his family, and future emperors as the Mausoleum of Augustus did not have enough room for another emperor. It was built near the Tiber, across from the field of Mars where many of the most important tombs were built in addition to along the Via Appia Antica). The Ponte Aelius was built in 134 AD to give access to the mausoleum. The mausoleum was finished in 139 AD under Antonius Pius. The structure consisted of a cylindrical center that was 70 feet tall and 210 feet in diameter on top of a square base that was 50 feet tall. The core was made of concrete and covered in tufa, peperino, and travertine. This can still be seen today when visiting the museum although most of the marble is now gone as it was taken by roman citizens in the fourteenth century when they were planning to attack the then fortress for the Pope.

After a century of use as a mausoleum, it was converted into the Fortress of Hadrian. This was during the period when the Aurelian's were building infrastructure to protect the city. The protection plan included building walls which surrounded the South side of the river and Trastevere, the Tiber River, and the fortress in the middle of the unfortified section of the river.

In 590, the fortress was reconstructed as Castel Sant'Angelo by Pope Gregory the Great during a time of trying to eliminate the plague. It had already been providing a protective purpose to the city since 547. In 1277, Nicholas III started to build protective walls around the Borgo and the Vatican, then called the Pasetto walls, as he wanted to move into the Vatican. From 1389-1404, Boniface replaced the statue of the chariot pulled by four horses and its base with a central tower. From 1447-55, four square shaped corner towers were built each being dedicated to an Evangelist. The corners that are now at the castle were built between 1492-1503 under Alexander VI and the outer pentagon of bastions was built starting in 1561 under Pius IV. In the sixteenth century, additions were made to the castle to turn it into a residence for the Pope. Under Urban VII, the walls connecting the bridge and the fortress were taken down. The current appearance of the castle can be seen below in Figure 10.

Figure 10: View of Castel San Angelo from the Pons Aelius

This monument is a great example of reuse through expansion upon the existing building. The space allowed for the building to continue to grow outward and serve a new purpose for each subsequent owner. Not many adaptive reuse projects today have this ability to expand outward as they are more confined by adjacent buildings and building codes.

Basilica di San Clemente

The Basilica di San Clemente is a very interesting site as it incorporates building from three different time periods. The basilica that is visible today was built in the twelfth century by Pope Paschalis II. It was built on a foundation of a fourth century basilica which was built on top of first century Roman buildings. The first century Roman buildings, now buried about 65 feet under street level, once served as a tufa stone structure and a brick apartment complex. The middle of the apartment complex was later changed into a Mithraeum. This room, once decorated with fine fabrics and pillows for the worshippers of Mithras to lounge and dine together, can be seen on a tour of the basilica but one must imagine this scenario. The basic structure is still intact but the decorations have been degraded or stolen throughout its lifetime. In the third century, a hall was built above the tufa structure for an unknown use. This hall was converted in the fourth century to the basilica that now acts as the foundation for the twelfth century basilica. It consisted of columned arcades and an apse above the Mithraeum. For the construction of the newest basilica, the fourth century one was filled in with ruble to be used as the foundation. The newest basilica was built so that the aisle and nave lined up with that of the one below it. It was built slightly narrower and taller than the one below because of the change in style of the roman basilica. The nave and aisles are separated by two rows of ancient columns that were taken from other sites. The ceiling is a beautiful combination of fresco, mosaic, and gold and the floors are multiple different patterns of colored tiles that were taken from the basilica below. Although the basilica was redesigned by Carlo Fontana in the eighteenth century, it still greatly resembles a twelfth century roman basilica.

Figure 11: Diagram of the layers of the Basilica di San Celemente

When touring the site now the space of 4th century basilica is cut off because of wall sections that were inserted to support the basilica above. These walls were created when the site was excavated in order to retain the structural integrity of the building. They were made out of materials found when excavating including ruble and some artifacts. This is a very sustainable way of restoring the underground basilica because the materials from the old building did not have to be brought off site and disposed of and not many new materials needed to be brought onsite. Not only would this be a sustainable practice but would also have cut costs for the renovations. This filling in of the arches can be seen in Figure 12 below along with the use of old stones and here old pieces of pottery to do this.

Figure 12: 4th Century church underneath Basilica de San Clemente

The ground level was probably rising because of silt, etc throughout time as it did all over Rome, so the top level of the 4th century basilica was most likely very close to the ground level at the time of the newest construction. Therefore, filling in the existing basilica to create a foundation was a very viable option for the new construction as the building was already partially or fully underground and probably saved a lot of man-hours and cost of finding new materials.

The newest basilica being built narrower and taller than that below was also probably structurally helpful since there would be a larger footing for the foundation and the load could be spread out over a greater area.

Reuse can be seen in the decorations of the 12th century church. The floor tiles were reused possibly from the church beneath or taken from another building in Rome. The columns, see Figure 13 below, on the interior of the church were clearly taken from other places in Rome and repurposed here. This is evident because none of the columns match. They are all different heights and have different capitals.

Figure 13: Columns inside the Basilica di San Clemente

This site is a very interesting example of reuse because it can be categorized into multiple types. First, it repurposed materials from older projects. Second, it technically had a complete reuse of foundation, basement, and above ground structure of the existing building except in this case the 'above ground structure' was really underground and was repurposed as a foundation for the new building.

Why We Need Adaptive Reuse

With more and more attention being brought to the issues of global warming and the need to focus on sustainability, the construction industry needs to take a closer look at how they can use more sustainable practices. In the U.S. approximately 1 billion square feet of buildings are demolished and replaced with new construction every year. It was projected that between the years 2005 to 2030, 82 billion square feet of buildings will be demolished and replaced; this is about one quarter of the existing buildings in the country (The Greenest 2011).

One individual reuse project cannot make a huge impact on carbon emissions, but when it is scaled to a whole city or country the impacts are huge. In Portland for example, if the buildings that would be demolished and rebuilt were instead reused over the next 10 years there would be a reduction of 231,000 metric tons of carbon dioxide emitted into the atmosphere. This adds up to about 15% of the country's total carbon dioxide reduction target over the next decade (The Greenest 2011).

Debris from construction and demolition currently make up 10-30% of the total waste in landfills in the United States and abroad. This amounts to about 136 million tons of waste with almost half of that from the demolition of old buildings to construct new ones (Laefer 2008). Only 20% of the total construction and demolition waste is recycled every year (AIA 2008). Figure 14 below shows a breakdown of the generation of construction and demolition waste generation in the construction industry.

waste chart.jpg
Figure 14:Construction and Demolition Waste Generation

Landfills in some parts of the world are beginning to near their capacity. If construction and demolition waste could be reduced this would greatly help with this issue as construction and demolition waste makes up a fairly large part of total waste in landfills.

In order to help reach the zero-emission goals set in the U.S. as well as to improve quality of living for future generations, adaptive reuse should be considered as an option for any building that is applicable. The Romans have shown us that buildings can last throughout centuries if they are well built and continually reused and restored. We should follow their example.

Works Cited

AIA Sustainability Discussion Group. "Construction Waste Management Strategies." AIA 50to50 Initiative (2008): 1-2. AIA Best Practices, July 2008. Web. 29 Sept. 2015. <>.

ASHRAE Journal 54.9 (2012): 6. Academic Search Complete. Web. 14 Sept. 2015.

Federici, Fabrizio. "The Reuse of the Ruins of Rome between past and Future." Archeology's Places and Contemporary Uses (2011): 37-41. Web. 15 Sept. 2015.

"Green Building Facts." U.S. Green Building Council. USGBC, 23 Feb. 2015. Web. 30 Sept. 2015. <>.

Grundmann, Stefan. The Architecture of Rome. Stuttgart: Axel Menges, 1998. Print.

Jacks, Philip. (2008). Restauratio and Reuse: The Afterlife of Roman Ruins. Places, 20(1), 10. Retrieved from:

Laefer, Debra F., and Jonathan P. Manke. "Building Reuse Assessment for Sustainable Urban Reconstruction." Journal of Construction Engineering & Management 134.3 (2008): 217-27. Academic Search Complete. Web. 14 Sept. 2015.

Maclise, L., T. Nelson, M. Kyler, G. Kang, S. Hohener, P. Littler, and A. Nudel. "Comparing Adaptability - A Case Study of Three Historic Buildings." Structures Congress 2013 (2013): 2767-778. Web. 16 Sept. 2015.

"The Greenest Building: Quantifying the Environmental Value of Building Reuse." (2011): 6-87. National Trust for Historic Preservation. Web. 16 Sept. 2015. <>.

Ward-Perkins, John B. Roman Imperial Architecture. New Haven: Yale U, 1994. Print.

Yung, E., Chan, E., and Xu, Y. (2014). ”Community-Initiated Adaptive Reuse of Historic Buildings and Sustainable Development in the Inner City of Shanghai.” J. Urban Plann. Dev., 140(3), 05014003.