A Study on the Architectural Conversion from Office to Residential Facilities - Through Three Case Studies in Tokyo -

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1 Session A-3: Conversion (2) A Study on the Architectural Conversion from Office to Residential Facilities - Through Three Case Studies in Tokyo - Hitoshi OGAWA, M.Eng. 1 Katsuhiro KOBAYASHI, Dr.Eng. 2 Nobuyuki SUNAGA, Dr.Eng. 2 Tetsuya MITAMURA, Dr.Eng. 3 Akira KINOSHITA, M.Eng. 4 So SAWADA, B.Eng. 5 Satoko MATSUMOTO, B.Eng. 5 1 Research Assistant, Tokyo Metropolitan University, , 1-1 Minamiosawa Hachioji, Tokyo, Japan, ogw9j8h@gmail.com 2 Professor, Tokyo Metropolitan Universit, , 1-1 Minamiosawa Hachioji, Tokyo, Japan 3 Research Fellow, Tokyo Metropolitan University, , 1-1 Minamiosawa Hachioji, Tokyo, Japan 4 Research Associate, Tokyo Metropolitan University, , 1-1 Minamiosawa Hachioji, Tokyo, Japan 5 Graduate Student, Tokyo Metropolitan University, , 1-1 Minamiosawa Hachioji, Tokyo, Japan Keywords: Architectural Conversion, Office Building, Residential Facilities, Case Study, Tokyo Abstract In recent years, building conversions from office buildings to residences have proliferated within Japanese metropolitan areas, due to the unstable condition of building stocks. With this in mind, we have been involved in certain building conversion projects from 2004, one of which was not realized, another, which was already completed, and the final one, which is currently at the design stage for execution. Upon completion of these designs, we organized and compared the basic data of these cases, for example, locations, building sizes, uses and certain features of the base buildings. From these analyses, the background of conversion was then clarified from both macroscopic and microscopic perspectives around the buildings. Next, we compared the plans, sections and uses, before and after conversion, and obtained certain methods specified for conversion for each of the cases. We also analyzed the processes from before to after conversion, especially from the perspective of design and the legal standpoint of building use. Finally we could reveal certain regenerating methods and problematic points concerning the utilization of existing building stocks. 1. Introduction The climate surrounding building stocks in central Tokyo has become very fluid in recent years. As an example, around the time of 2003, there was a surplus of newly constructed office buildings, and the issue of an increase in the rate of vacancies within existing stock arose. Since that time, many methods have emerged to regenerate stocks, involving the conversion of vacant office buildings into residences. Currently, although the market is predominantly occupied with recovering the balance, the supply quantity of new buildings remains redundant. In fact, reconstruction of existing stocks is proceeding in combination with an economic boom, meaning the total amount of stock remains constant. Under such circumstances, however, methods of regenerating and utilizing stock can be deemed effective from the environmental and city regeneration perspectives, and those will also continue increasing in future. This research aims to clarify the methods used to regenerate existing building stocks and problematic points for the realization of the same, by examining the methods based on the cases of conversion in which we are involved, and from various perspectives, covering office buildings to residences. 171

2 2. Actual circumstances of the building market in central Tokyo In Japan, despite the stagnancy affecting the construction of office buildings following the bubble economy, which lasted from the late 80s to the early 90s, the building supply has since rocketed. Subsequently, the supply quantity has experienced smooth recovery, in line with Japanese economic trends, with 2003 recording an excess in building construction. Consequently, office buildings were overstocked, raising the issue of an increase in the rate of existing stock vacancies. Subsequently, rents of compact office buildings dropped to the level of housing rent or below, and ever since, the conversion of vacant office buildings to residences has become a visible phenomenon. At present, while the supply quantity of new office buildings is still redundant, conversely, the office building market is recovering the balance, due to an increased ratio of the reconstruction of existing stock. In addition, the active situation of the housing market remains ongoing, while the quantity of vacant housing stock has plummeted. The aforementioned data thus indicates that the demand for offices matches the newly constructed major office buildings, and that likewise, the demand for housing matches the major new housing construction. Moreover, in the near future, the ratio of vacant office stocks will climb as the baby boomers start retiring in 2010 and the market competition intensifies. Since this will represent a challenge facing conversions of small office buildings to residences from a quantity-based perspective, there will be a need to clarify target tenants and redesign buildings utilizing their special features in the conversion. 3. Outline of three case studies We are involved in three conversion projects; with terms ranging from 2004 to Although one remains unrealized (Y building), another has already been completed (M building), while the final one currently remains at the design stage for execution (G building). Firstly, we briefly outline three projects in this chapter Y Building This building is located in Kanda, a downtown area in central east Tokyo, and accessible from the station within 10 minutes on foot, at the corner of a narrow back street. This building, which has been used for offices, has 6 stories and 1 basement, a footprint of 225 square meters, and total floor area of 1360 square meters. Construction was completed in 1990, about 14 years previously to the project in which we were involved in Fig. 1 Y Building before Conversion and its Surroundings In Kanda, although there are some big developments along major streets, city blocks tend to be full of small buildings called pencil buildings. Although Y building is in relatively good condition based on the aspect of floor size, despite deterioration of the building equipment and finishing, it still has some vacant floors, which is presumably attributable to its location. With this in mind, we proposed a more effective design and renovation program for attracting tenants. 172

3 Session A-3: Conversion (2) We proposed a floor divided into small rooms, which would be usable by small businesses consisting of one or two person/s, and a working style incorporating many shared areas, usable as meeting spaces, factories, and cafes, as well as small private rooms. As the floors advance upwards, we clarify their articulation, expand their size, and gradually highlight the residential function. Finally, the upper level of the building is occupied by rooms which function intermediately between an office and a residence. Fig. 2 Proposal for Y Building In this project, our proposal was based on the idea of mismatches that occur between buildings and companies, especially from the aspect of size. We designed the entire building interior based on a recommendation for small companies to connect to the urban community as an extension of mutual company communication within the building, reflecting the nature of Kanda as a very traditional, characteristic city M Building This building is located along a cozy little shopping street near a small station, located about 30 minutes from central Tokyo by train. As a typical structure within a time-honored shopping street, it has a narrow frontage and a considerable depth, as well as complicated usage. The first floor was used as an office and shop, the second floor as a residence, and the third floor for an atelier. The building size is 3 stories, with a footprint of 173

4 Fig. 3 M Building before Conversion 67.4 square meters, and total floor area of square meters. 26 years had passed since the completion of construction when we got involved in its renovation in This shopping street is declining, as the managers of small shops retire, with major retailers moving into the adjacent big station, and its appearance is being drastically transformed. We regenerated this building for two households, into residences and a home office. The existing building had an external stair, with floors that are independent of each other, so we took over its composition, and added a different character to each floor. On the first floor, the existing partition walls were removed to leave a single long space, softly articulated into a few areas and characterized by structural rhythm. In the second floor, based on functional requests, we insert many walls into the long building Fig. 4 Proposal for M Building 174

5 Session A-3: Conversion (2) skeleton, and generate repeated rooms, each with different characters. Meanwhile, the third floor is settled as an annex, and its space is utilized without articulation. In this project, one of the important themes involves creating a new relationship between a building and a street. This is not an activation of the street as a shopping street, but rather a promotion to change its character as a human street, whereby shops and residences are mixed. On the first floor, we create a gradational layout of space that gets the public closer to the street, helping residents improve their relations with the outside, and vice versa G Building This building is located alongside a major busy urban ring road. There are many small factories in its vicinity, and it has an atmosphere like that of downtown. It takes 15 minutes from the nearest station to this building, and there are very few pedestrians along with ring road, with most coming by bicycle. This small but tall building had been used as an office, with 6 stories, an 83 square meter footprint, and total floor area of 360 square meters. A period of 16 years has elapsed since the completion of construction, making it relatively new, although many areas have deteriorated due to leakage caused by rain. Moreover, since there were no tenants when we became involved in this project, we decided to convert this building from an office to housing, with the surrounding market in mind. Fig. 5 G Building before Conversion and its Surroundings We proposed a single housing unit per floor from the second to the sixth floor, and a continuation of the office on the first floor, due to its environmental incompatibility. To resolve the problem of noise from the ring road, we established a space adjacent to the facade, with partitions separating the space from the room inside, in order to create a double-skinned facade. This space includes a dirt floor, and is expected to be used as a major entrance, a recreation area (for bicycles, gardening...), and an annex room, as if it were outside. The room 175

6 Fig. 6 Proposal for G Building inside the partition, meanwhile, includes just a single big wall on the north side of the floor, with a space provided for utilities on the far side of the wall. This wall is set as a major correspondence to the undulation of the existing external wall, in order to generate soft articulation and depth into the vacant floor. This building has an irregular configuration, tapered as it rises due to the building code, meaning the floors become smaller as the height increases. We applied the same manipulation to each floor, but the diversity generated led to the characteristic configuration of the existing building. 4. Comparison and Analysis of three case studies Once the designs for the three projects were completed, we organized and compared the data obtained from these projects. The three projects are independent; each with its own context. We analyzed the three projects from a physical perspective and aspects of change of usage of building Methods for renovation We extracted some specific methods for renovation, independent of context, for each project. One of the remarkable methods used in the Y building involves a vertically gradational building composition 176

7 Session A-3: Conversion (2) that clarifies the room articulation as the floors get higher. This is a method used to organize the whole building. As for other methods used, those standing out include the creation of many booths with partitions, and lofts, for example. In the M building, the most interesting method involves applying quite different operations for each floor, and layering them. These are delicate and soft, while also clear and powerful on the other hand. As another remarkable method, on the first floor, there is a horizontally gradational composition concerning the usage of space, whether private or public, and involving both proposals for the interior and exterior faced surroundings. The G building incorporates a simple system, but various floors and although the same operation is applied to all floors, diversity still occurs based on the irregular configuration of the building. In the interior, the position of the walls is determined by the undulation of the building skeleton. These factors are dependent on the existing building, but also represent a skillful diversion of the building character. Another remarkable method is the setting of partitions in order to create a double-skinned facade. The common terms in the three projects are the existence of a method for articulation, and one for organization that can also be called a method for syntagm. On the other hand, the specific methods used for each project are: sectional operations in the Y building, the application of many operations relating to articulation in the M building, and operations involving the new relationships established with surroundings in the M and G buildings. These methods are either site- or building-specific, and directly connected to the essence of the proposal. From the viewpoint of the relationship between each of the methods and the context, it is clear that there are both methods responding to one parameter, and methods responding to many parameters. Moreover, the fact that the methods used are inter-linked is also clear. These aspects would strengthen the proposal and clarify its direction. Fig. 7 Interior View of M Building (Left) and G Building (Right, Photo Collage) after Conversion 4-2. Processes of conversion The three projects all relate to residential facilities and include the replacement of office buildings with residential facilities, to one degree or another. Along the way, the legal problem concerning conversion of building use arises. We compared and analyzed the methods used to insert the residential facilities, and the change in the legal position of the buildings, both before and after conversion. In the Y building, from its mid or upper level, we inserted the residential functions on a gradual basis with advancing height, and in this case, residential facilities were set in the form of collateral facilities added to the office. Consequently, rooms in the upper level of the building incorporate intermediate functions between offices and residences and we resolve the project with no change of facilities from a legal perspective. As with the Y building, the M building also sees an unchanged legal position. On the first floor, we inserted residential functions using a method equivalent to that for the Y building, while on the second floor upwards, 177

8 we reinforced the existing residential functions. The three projects all involved specific cases, since the owner of the building had bought it with a clear vision concerning its future utilization. The G building is the only project in which we converted the building facilities from a legal perspective, exclusively incorporating housing alone between the second and sixth floors. However, a further critical problem of the lack of procedure for legal permission arose at the time of construction, meaning the ongoing project faced many restrictions. Based on the aforementioned analysis, it is clear that there are many methods available to residentialize the building, as far as manipulation is concerned. In reality, advancing information technology means the line between business and dwelling is blurred, raising the possibility of adjusting the building facilities while maintained an unchanged legal status as far as possible. On the other hand, it is definitely effective to convert building facilities with unchallenged legal permission, although numerous buildings can be presumed to have irrelevant aspects from a legal perspective, just like G building, in Japan, meaning it might be preferable to clarify the means of correcting the legal position of those buildings in future, and obviously ensuring legal permission. 5. Conclusion Since the three projects in which we are involved are comparatively small, with costs strictly limited in each case, we did not manipulate the relevant factors to such a drastic extent. Moreover, generally speaking and in terms of dwellings, the first thing to highlight is the unlimited possible solutions. Based on such assumption, we were able to reveal certain key points concerning the conversion from office to residential facilities; namely that articulation within a floor is an important factor for creating a specific proposal, and that in addition, organization, such as the method used to layer floors, is also a remarkable factor. These solutions are based on reflection of the microscopic environment (building), and macroscopic environment (surroundings). Moreover, when dealing with complicated conditions, it is effective to apply a method whereby many requirements are resolved at the same time, or linking some methods functionally. During conversion from office to residential facilities, especially buildings with hard conditions, there is the potential to use methods partly involving far-fetched solutions to requirements, which also lead to reflections of its context. There are innumerable such cases in cities and many variations are currently devised for the manner of utilization. Basically, the regeneration of stock involves success and failure being questioned by the economic aspect of business. However, there is also a need to inspect the effect, not only from temporary, local viewpoints but also longitudinal, urban viewpoints, so that more effective utilization can be perpetuated. Acknowledgments This paper presents certain findings from the following research projects "The 21st Century COE Program of Tokyo Metropolitan University: Development of Technologies for Activation and Renewal of Building Stocks in the Megalopolis", subsidized by the Ministry of Education, Culture, Sports, Science and Technology, Japan. Thanks are due to Susumu Minami for his valuable advice concerning building structures in the G building project, Maria Ojimi, Kogo Matsuno and Sayaka Ito for their assistance in the prosecution of G building project, Sunao Chiga, Hiroki Endo and Taichi Murayama for their assistance in the prosecution of the M building project, and Yuki Takahashi for assistance in the prosecution of the Y building project. 178