Historically significant buildings can be defined as buildings with distinctive physical and spatial qualities that manifest architectural and historic value, improve our understanding of the past, and typically demonstrate exemplary design techniques associated with a certain architectural style or historic period. To be classified as a historically significant building, a structure needs to be of sufficient age, a relatively high degree of physical integrity, and demonstrate historical significance. In terms of sufficient age, structures that are more than 50 years old are generally considered historic. Physical integrity refers to the state of the building—to be classified as historically significant, a building must be relatively unchanged, maintaining its characteristics and exemplary features. Historic preservation, in the context of architecture, is the process of preserving and protecting historically significant buildings. The primary goal of preserving historically significant buildings is to maintain the original character, architectural features, materials, and overall design intent. If historically significant buildings need to be renovated, the procedures are quite specific and different from other buildings—all the interventions need to be planned and executed in such a way as to maintain the original architectural design intent. This case study reviews research that was conducted for a historically significant building to determine and analyze original design features, assess the building’s current state and performance, evaluate how its current performance relates to the original design, and propose renovation strategies that would improve the building’s performance while maintaining the original design intent, particularly focusing on the building skin. The building, Spomen Dom (literal translation “Remembrance Home”), is an exemplary building of the Brutalist architectural style built between 1971 and 1975, located in Kolašin, Montenegro (formerly Yugoslavia) and shown in Figure 5.1. Designed by the Slovenian architect Marko Mušič, the building abstractly expresses vernacular forms present in this region, specifically traditional sloped residential roofs shaped in response to harsh winters, but in a different material—concrete. Figure 5.2 shows a sketch of Spomen Dom’s form and relation to the surrounding context. It was originally designed as a memorial and cultural center, but parts of it have been repurposed. The historical significance of this building lies in its expressive architecture, relationship to the context and history of this region, and exemplary design features that reflect the Brutalist architectural style. After the initial literature review relating to this building and the research goals, it was found that current studies that focus on analysis of its performance do not exist. Some literature sources were identified that captured design features, historical context, and significance of this building. However, existing studies that focus on its current state and performance do not exist. The research questions that were addressed include: In order to address these questions, qualitative and quantitative research methods were chosen, as shown in Figure 5.3. Particularly, archival research was used to address the first two questions, which included collection of the original architectural records, drawings, diagrams, documents, and photographs. The original documents had to be translated, since they were written in the Serbo-Croatian or Slovenian language. Observations were used to address the third research question, which included visits to the building, observations of the exterior and interior spaces, documentation, and photographing. The results of archival research and observations were used in the subsequent research process. Simulations and modeling were used to address the remainders of the research questions, where a BIM model of the building was developed to represent the original and current spatial organization and to analyze its performance in relation to passive design techniques (solar radiation and window-to-wall ratio). Combined heat and moisture transport analysis was conducted to analyze building skin performance. Lastly, the entire study is a case study because it focuses on detailed analysis of a single building. However, it demonstrates research procedures that can be applied to other types of research studies that focus on building performance analysis of historically significant buildings. The results of the archival research showed that the conceptualization of this unusual building with multiple civic and administrative programs was a result of the political movement and economic prosperity of its time. The reviewed archives included the original architect’s documentation, city hall archives, and local university’s archives. The primary purpose of Spomen Dom was to symbolically commemorate Yugoslavia’s victory over fascism during World War II, to inspire, celebrate, and strengthen its ideology, and to promote collective participation in cultural events. Spomen Dom was designed as a cultural center, memorial museum, and an administrative municipal building. The building is a prime example of Brutalism, an architectural style based on expressive geometric forms and concrete construction. In the context of Yugoslavian architecture, Brutalism was used from the 1950s to the 1980s as the dominant style to demonstrate the country’s progressive ideology (Stierli and Kulic, 2018). Civic buildings like Spomen Dom were especially designed as futuristic, progressive structures with extremely high budgets that reflected cultural identity in a modern way (Niebyl, 2018). The main goal was to democratize architecture and to make it widely available for people to enjoy, use, and inhabit. Buildings like this were meant to create innovative forms of public spaces, where education, cultural events, entertainment, and political activities were intertwined. However, with the collapse of Yugoslavia in 1991, these ambitious and stylistically explorative projects abruptly ended. Currently, many of the buildings are systematically neglected, abandoned, in ruin, demolished, or repurposed. Some of the buildings faced targeted destruction as the political context changed, and socialist ideology was no longer widely accepted. The observations that were conducted showed that Spomen Dom is currently in partial ruin, while a portion of the building is used as office spaces for the municipal services. Public gathering and cultural spaces have ceased to function. In the late 2000s, demolition and redevelopment of the project were planned, but these plans were abandoned. Little effort has been made to preserve the building’s existence, regardless of its historical significance and architectural qualities. The building was initially composed of three types of spaces, which were differentiated through size, volume, and materials. These included public halls, office spaces, and support spaces. The core compromised a “citizen’s vestibule”, which was surrounded by public halls. Two administrative wings—one longer on the west and one shorter on the east—extended from the public part of the building. The support spaces were placed on the lower level. Figure 5.4 illustrates the building program and spatial organization according to the design intent, while Figure 5.5 shows the current state and indicates parts of the building that are in ruin. Figure 5.6 shows photographs of the current state of the interior of the building. The results of archival research and observations were used to develop a detailed BIM model of Spomen Dom, using the Revit software program, shown in Figure 5.7. This model was used to evaluate building performance (passive design strategies), response to solar radiation, shading, window-to-wall ratio, and building skin performance. Spomen Dom’s north and south facades are elongated, while those of the east and west are minimized. The building’s shape responds to solar orientation, but there are very few differences in facade treatment for different orientations. Moreover, the relatively equal window-to-wall ratio between south and north facades is present. The solid mass prisms with triangular windows have a similar exterior treatment and size of glazing, regardless of the orientation. A BIM model was used to study shadows during different times of the year, as seen in Figure 5.8. Insight 360 Solar Analysis software was used as a simulation tool to evaluate solar radiation, as shown in Figure 5.9. Results indicate that the north elevation is exposed to direct daylight, and there is potential for solar heat gain in the early morning of the summer season—at all the other times, it is in complete shade. Since the building is located in a heating dominated climate where approximately eight months of the year require heating, the glazing along this elevation does not utilize passive solar heating. The results for the south elevation indicated that the administrative wings are facing direct sun at almost all times, and the only time that the offices are in shade is early morning in the summer. The solar radiation along this orientation is high. A double skin glazed facade is utilized along the south orientation, shown in Figure 5.10, which was quite an advanced building technology for the time when Spomen Dom was built. The main advantage of double skin facades is improved thermal performance. This double skin facade is vertically compartmentalized, spans from the ground level to the roof, and includes windows on the exterior side for ventilation, consisting of single glazing units. The adjoining offices have operable windows at the base and at the head of each level, which improve air circulation within the double skin cavity. Since air conditioning systems were not common at the time when the building was designed, the operable windows were intended to provide natural ventilation and cooling in the summer. There are some discrepancies between the original drawings and the constructed double skin facade. The operable windows were drawn as 180-degree rotational panels, but the actual installed windows only partially open at about 45 degrees. Also, horizontal blinds are shown in the air cavity as shading mechanisms, but these are not present in the current building (only vertical shades that are located further away on the interior side). Therefore, deviance from the construction documents may have negatively impacted the performance of this system. Installing a mechanical fan on the roof may help with air circulation and ventilation of the double skin cavity, as well as adding shading devices in the cavity. Solid wall assemblies were also analyzed. The typical concrete exterior wall was investigated, as seen in Figure 5.11. Material components and their properties were identified, and the overall thermal resistance of the assembly was calculated, which slightly exceeds the minimum recommended values for this climate. Simulations were performed to investigate combined heat and moisture transport using the WUFI software tool. The results have shown that significant moisture is retained on the building interior, likely due to the lack of an air cavity, insufficient insulation, two material layers that are trapping vapor within the assembly (epoxy coating on the exterior surface of the concrete and a vapor barrier between concrete and insulation), and the porous nature of the hollow masonry that is the support plasterboard interior finish. The solid wall and the triangular skylight for the typical prism component were also investigated, as seen in Figure 5.12. Thermal resistance of this assembly was calculated and exceeds minimum recommendations. This assembly includes a punched pyramidal opening with thick single layer glazing units—two per volume. Simulations were also performed for this assembly, and the results indicated that moisture is retained in this assembly as well. The final research results showed that the building skin of Spomen Dom is not well-performing and is adding to the deterioration of this architecturally important building. In order to preserve its state, careful renovations of the building skin would be required. These should include adding insulation on the building interior for the solid walls, incorporating continuous waterproofing, and adding air cavities. The skylights would also benefit from double insulated glazing units, to improve thermal performance. The double skin glazed facades would need to incorporate double insulated glazing units on the exterior skins, add shading elements within the cavity, and integrate small mechanical fans on the roof to help with the ventilation of the cavity. These changes would maintain the original design intent but would improve the building performance of Spomen Dom. Buildings like this deserve to be cherished and celebrated. Adaptive reuse of existing buildings is a growing area of architectural design, engineering, and construction. Adaptive reuse is the process of renovating an existing building, applying retrofit strategies, and transforming the building’s function to a new purpose. Adaptive reuse often focuses on buildings that do not have historic significance; therefore, the design and retrofit approaches are different from historic preservation projects. The architectural expression, choice of materials, and design interventions do not necessarily have to reflect the building’s original design intent. Adaptive reuse is an important aspect in sustainable and resilient design because it reduces our reliance on new construction, as well as the embodied energy and carbon emissions associated with new construction. Energy-efficient retrofitting of existing buildings can significantly lower our dependency on fossil fuels and improve building performance across the board. Through reusing and upgrading existing buildings, performance of the existing building stock can be improved, thus bringing more opportunities to reinvigorate and benefit local economies in the long run. Moreover, integrating Net-Zero Energy Building (NZEB) concepts into building retrofits can improve the energy efficiency levels in existing buildings and apply renewable energy sources to reduce their dependence on external energy infrastructure. Since the life of existing buildings is extended and possible demolition waste is avoided, net-zero energy retrofits also contribute to the development of sustainable and resilient urban environments. Typically, achieving net-zero energy goals can be realized through implementing passive design strategies, improving building enclosures, installing high performance HVAC systems to reduce heating and cooling loads, and reducing lighting and other electric loads, thus making it possible to offset the required energy balance with renewable means, such as photovoltaics or wind turbines. Figure 5.13 shows appropriate steps that should be implemented in achieving net-zero energy buildings, as well as the economic impacts, risks, and benefits associated with advanced building technologies. Passive design strategies should be implemented to reduce energy consumption as much as possible, since their costs are relatively low. Advanced building technologies, such as energy-efficient lighting and HVAC systems, as well as high-performance building envelopes, should then be employed, since their costs are higher, but they can significantly reduce a building’s energy consumption. Lastly, renewable energy sources must be used, but only after passive design strategies and advanced building technologies are exhausted since their costs are high. Figure 5.13 shows appropriate steps that should be implemented in achieving net-zero energy buildings, as well as economic impacts, risks, and benefits associated with advanced building technologies. Achieving net-zero energy goals is a challenging objective, especially when it comes to retrofit projects, because more constraints are typically imposed on existing buildings than new construction. This research study explored applicable passive and active design approaches that can be integrated to achieve energy savings by investigating feasible retrofitting techniques for building performance upgrading. The research focused on a specific case study, a commercial building located in Holyoke, Massachusetts (Aksamija, 2016; Aksamija and Wang, 2017). Also, the study investigated the ways to combine renewable energy generation installations to provide on-site renewable energy to meet net-zero energy goals. These following research questions were addressed: The research methods that were used to address these questions included qualitative and quantitative methods, as seen in Figure 5.14. Archival research was used to collect information about the existing building and its history, while observations were used to assess the current state of the building. Information about the original building was obtained and analyzed to develop redesign strategies that would facilitate the achievement of net-zero energy goals. Case study research was used throughout the research process since the study focused on a specific building. Simulations and modeling were used to assess the impacts of adaptive reuse design strategies on energy consumption and to quantify the performance of renewable energy systems. Energy modeling was used to drive design decisions, where the initial energy model that was built assessed the impact of retrofitting design strategies, such as change in building massing, impacts of daylight, improvement in building envelope, and retrofitting of lighting and HVAC systems. Then, an alternative energy model was developed which investigated the maximum energy savings that could be achieved by the combined design strategies. Different parameters within energy models were varied to perform a comparison of the base case and alternative design scenarios. Based on the calculation of annual energy balance and consideration of local climate and available resources, specific types of renewable energy generation installations were selected and integrated in the retrofit design program to ensure that sufficient energy could be generated on-site to offset the annual energy balance of the building to zero. Although the results of simulations and modeling are applicable only to the discussed case study building, the methods are applicable to any retrofit design project. The building that was chosen as a case study for this research is a 200,000 ft2 (18,587 m2) commercial building located in Holyoke, Massachusetts. The building was originally designed as a paper mill and built in 1895, but it has been renovated several times in its history. Currently, the majority of the building is abandoned, while a small part is used as a commercial office space. As part of the revitalization plan for this area, retrofits of commercial buildings would contribute to the development of a stable, healthy, and desirable neighborhood. Figure 5.14 shows the building’s context and the surrounding area, while Figure 5.15 presents the building site and the current conditions. The first step in adaptive redesign was to analyze the massing of the existing building, structure, and spatial organization and to determine how exactly the building form could be changed and improved. Building shape, orientation, and volume can significantly affect energy consumption (Aksamija, 2017). This is much easier to accommodate in new construction since the building form and massing can be determined from the early stages of the design process. In existing buildings, this is more complicated since the building form is already predetermined. For the case study building, building massing and form were modified to allow for daylighting and natural ventilation. Extensive BIM modeling was implemented to investigate changes to the building’s form and shape. It was determined that parts of the building should be demolished (mainly, parts of the second and third floor) and that two additional floors would be added to accommodate the new building program, as seen in Figure 5.17. The new program includes offices, classrooms, gallery space, retail space, and public space (community center). The program for the first level is shown in Figure 5.18. The middle part of the building was redesigned into a courtyard, which allowed the building to get back to its original appearance (the initial interior courtyard was closed off in the 1960s). With this retrieved courtyard, daylighting and natural ventilation were integrated as passive design techniques to reduce electricity consumption. Extraction of the existing building mass and addition of a new building mass created several roof gardens, which would offer public space for occupants and provide an area for placement of photovoltaic panels. Figure 5.19 depicts vertical transportation, circulation diagrams, shading system, and green roofs. Building envelope upgrade strategies included improving the exterior wall insulation to control the heat, air, and moisture transfer between the wall assemblies and the exterior environment. Newly added thermal insulation, an air barrier, and a vapor retarder would help the building acquire improved insulating and air sealing performance. For the top two floors, a new facade system was designed to provide an appropriate visual environment for the office areas and make full use of daylight to reduce energy consumption for lighting. A curtain wall system and an exterior horizontal sunshades system were combined to achieve environmental optimization and energy efficiency. The shading system would control the direct solar exposure and glare, making the interior daylighting environment ambient and comfortable. An energy-efficient HVAC system was integrated into the design, consisting of a radiant heating and cooling system and biomass heating. Since wood, agriculture residues, and crops are the most common fuels for biomass energy systems, easy accessibility to these organic matters in the western Massachusetts area would lead to reduced delivery and storage costs. Simulations of energy performance were conducted using the eQuest energy modeling software program. Two different models were simulated and analyzed to explore the energy savings potential of different design strategies—the initial baseline design and an alternative design. Renewable energy sources are necessary to achieve net-zero energy goals, and the energy modeling results also indicated how much energy would be required to meet those goals. Comprehensive thinking towards energy conversion ratio, feasibility, accessibility, and cost contributed to the decision of selecting four types of renewable energy systems that generated enough energy to support the operation of the building. Figure 5.20 shows sustainable design strategies that were considered in this adaptive reuse project, as well as renewable energy sources. Table 5.1 shows basic inputs for the energy models, and Table 5.2 shows occupancy schedules. TABLE 5.1: Inputs used for energy modeling. TABLE 5.2: Occupancy schedules used for energy modeling, according to building program. The baseline simulation results showed relatively high annual energy consumption, with an Energy Use Intensity (EUI) of 120 kBtu/ft2 (378 kWh/m2). Deep retrofit measures designed to address this problem incorporated control of internal loads and operating schedules, lighting, and improvement in the building envelope. For museums, classrooms, retail spaces, and offices, different demands for the interior lighting environment and occupancy schedules were taken into consideration in the energy modeling improvement process. Lighting power density (LPD), which is an important value associated with energy efficient lighting design, was reduced for all spaces in the building. In addition, planning and rescheduling work time for every functional room made it possible that significant lighting energy could be saved according to occupancy levels, and integrated occupancy sensors would ensure that lighting electricity is minimized. Other energy efficiency approaches included using materials that have high thermal mass and durability, as well as applying glazing with lower U-values. Since windows account for most of the energy loss, improving glazing is an effective way to reduce energy transfer through the windows. Double glazing with a low-e coating and argon gas fill was selected to substitute glazing for windows, thus significantly reducing heat transfer through the building envelope. After applying all the possible energy saving strategies, an alternative simulation run in eQuest was conducted to acquire a comparison analysis, lowering the EUI value to 52 kBtu/ft2 (163 kWh/m2).
5 Case Studies
5.1 Qualitative and Quantitative Research for a Historically Significant Building: Building Performance Analysis of a Brutalist Building
Spomen Dom, current state. Courtesy of Sunčica Milosević.
Spomen Dom and sketch of its surrounding context.
Overview of research questions and research methods.
Floorplans of Spomen Dom, according to original design intent, and spatial organization. Courtesy of Sunčica Milosević.
Floorplan of Spomen Dom’s first level, as currently used. Courtesy of Sunčica Milosević.
Spomen Dom, current state of the interior spaces. Courtesy of Sunčica Milosević.
BIM model of Spomen Dom. Courtesy of Sunčica Milosević.
Shadow analysis. Courtesy of Sunčica Milosević.
Solar radiation analysis. Courtesy of Sunčica Milosević.
Double skin glazed facade, and its current state. Courtesy of Sunčica Milosević.
Typical concrete exterior wall assembly, thermal resistance, and simulations of combined heat and moisture transport. Courtesy of Sunčica Milosević.
Typical prism exterior wall assembly, thermal resistance, and simulations of combined heat and moisture transport. Courtesy of Sunčica Milosević.
5.2 Qualitative and Quantitative Research for Adaptive Reuse: Designing for Net-Zero Energy
Design methods for achieving net-zero energy in buildings, and associated benefits and risks.
Overview of research questions and research methods.
Surrounding context of the case study building.
Site plan and current state of the building.
Comparison of the original building and its adaptive reuse design, outlining major changes to the building.
Floorplan of the first level, showing the new building program.
Adaptive reuse building diagrams. Courtesy of Yi Wang Vizard.
Sustainable adaptive reuse design strategies and renewable energy sources. Courtesy of Yi Wang Vizard.
