Re-evaluation of Functionalist Houses: A
Passive Energy Efficiency and Daylight
Analysis Using BIM Tools
Rafiullah Sherzad
Awrangzib Imamzada
MASTER THESIS 2021
Master in Product Development with a specialization
SUSTAINABLE BUILDING INFORMATION MANAGEMENT
This thesis work has been carried out at the School of Engineering in Jönköping in the
subject area Product development - Sustainable Building Information Management.
The work is a part of the Master of Science with a major Product development,
specialization in Sustainable Building Information Management.
The authors take full responsibility for opinions, conclusions and findings presented.
Examiner: Annika Moscati
Supervisor:
Amjad Zaki Khalil Al-Musaed
Scope: 30 credits (second cycle)
Date: 06/06/2021
ADDRESS:School of Engineering, P.O Box 1026, SE-551 11 Jönköping, Sweden VISIT:Gjuterigatan 5, Campus, Building E
PHONE:+46 (0)36 10 10 00 WEB:www.ju.se
Re-evaluation of Functionalist Houses: A Passive Energy Efficiency and
Daylight Analysis Using BIM Tools
Rafiullah Sherzad1 and Awrangzib Imamzada2 1 Jönköping University, Jönköping 551 11, Sweden 2 Jönköping University, Jönköping 551 11, Sweden
shra19qo@student.ju.se imaw19ej@student.ju.se
Abstract. Western Europe Functionalism ideas are born of the need for scientific and technological progress in
producing new materials and building technologies. Today energy efficiency has become one of the most important characteristics of any project, where functionalism reflects well-designed building components. Reducing energy con-sumption, improving energy efficiency and minimizing greenhouse emission in the building is vital for the planet's survival. This study intends to provide expertise in design and construction disciplines to use the idea concept of Fall-ingwater and Villa Savoye, functionalist-style buildings, from the golden era of functionalism. This evaluation can help a new generation of designers and architects to improve the passive energy efficiency and daylight of studied concepts, pragmatic and organic. As a case study, the authors simulated and evaluated the energy efficiency of two conventional architecture designs stated above. Energy efficiency and daylight simulation of these functionalist-style buildings were executed using the BIM-based Building Energy Simulation (BES) tool. The indoor temperature variation and the amount of illuminance for each zone were assessed. The result indicates that the main temperature variation (mean air and operative temperature) in both buildings is not suitable for living and some parts of the regularly occupied floor receive too much direct sunlight. Based on the results, some passive energy-saving measures such as improving build-ing orientation, material and shape, window wall ratio (WWR), addbuild-ing external shadbuild-ing device, window position, and size are suggested to help researchers in AEC industry in the future reforming process.
Keywords: BIM, Energy Efficiency, Daylight, Functionalist style, Pragmatic functionalist style, Organic functionalist style, IDA ICE.
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Introduction
An architectural style is a collection of characteristics and features of the architecture. Functionalism establishes the correct use of space, the correct layout of the premises and sets the rules according to which the design should be built to achieve maximum functionality. In many fields such as engineering and medicine, the term efficiency is used broadly. In each area, it is used with different meanings, such as effectiveness, saving, and performance. The main objective of using the efficiency term is to attain the maximum output from a system with relatively few resources (inputs). The meaning of energy efficiency is to have the same result from a smaller amount of energy or attain a large amount of energy from the same input [1]. In recent years, energy, as well as methods for gener-ating, transmitting, and consuming it, has received a lot of attention around the world. As a result, numerous engineering fields have placed a greater emphasis on the energy usage of their projects and designs [2]. The use of energy by building accounts for approximately 40% world's energy consumption including up to 65% of elec-tricity. If they are managed well, they have the potential to save a significant amount of energy and carbon dioxide emissions. A big part of the energy in residential buildings is consumed by HVAC (heating, ventilation and air condition) systems and lighting [3][4]. Therefore, the main goal with the energy efficiency is to lower the energy consumption of buildings consumes for the purpose of thermal comfort, lighting, vertical transportation and
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domestic hot water [5]. The building type, materials, and other relevant factors significantly affect the indoor thermal comfort and lighting energy of the air-conditioned or naturally ventilated buildings. The building shape, orientation and the Window Wall Ratio (WWR) of a building are the most significant parameters for lighting, energy requirement and the thermal comfort of a building [6]. These parameters are interrelated, and a proper combination of these parameters is needed to acquire optimal thermal comfort and energy efficiency. A study conducted by Goia [7] to determine the best WWR for various climates in Europe. The study found that different optimal values exist for different environments, but the best result is provided by 30-45% of WWR, while values outside of the given range may be appropriate for south-facing facades in buildings in extremely cold climates [7]. As stated by Kim et al. [8] a building requires the lowest energy load when the midpoint of a window is positioned in the middle of the wall. They also found that annual energy consumption increases when increasing the size of the window regardless the position of it. Martyna [9] found that the building shape plays a pivotal role in terms of heating energy consumption. According to her study, the square shape has pros over L, C, U and rectangular shapes when it comes to heating energy consumption. Wang et al. [10] examine the effects of climate on heating and cooling demands in five environments and conclude that climate change greatly influences buildings that perform poorly. Likewise, the impact of building orientation on energy usage has been studied by Miomir et al. [11] who found for the cold climate that building orientation, where the biggest part of the window surface is oriented toward the South, contributes to the reduction of heating energy demand. Energy optimization both in residential and non-residential buildings regarding energy efficiency is thoroughly analyzed in this modern society because they are contributing at a large scale in energy consumption globally [12]. Even though techniques and innovations for minimizing energy use and environmental impacts are available but their application in residential buildings has been lacking [2].
Another essential aspect that can reduce energy consumption is a daylight integrated lighting solution. Increas-ing the amount of daylight in a dwellIncreas-ing, save energy, minimize greenhouse gas emission, improve visual comfort and increase the quality of indoor climate [13]. Insufficient daylight causes physiological and psychological prob-lems, which sometimes lead to sickness [14].
As is stated above, numerous studies have been done which could help to reduce and optimize the energy consumption of buildings. Moreover, the literature review shows that the articles published regarding the func-tionalist style buildings investigated the confirmation of spaces, building material uses, orientation, the relationship between inside and outside environment, and function of the spaces [15]. However, none of the current and previ-ous studies has been addressed the energy efficiency in buildings of the earlier functionalist style by applying BIM-based tools. Additionally, no researchers have investigated and put efforts to provide practitioners with knowledge regarding the earlier important functionalist style of architecture which can be re-used their concept by reforming them according to the new sustainable building regulations and residence requirement. Recently, prac-titioners around the globe are putting efforts to reduce energy consumption in buildings because it is related to both environmental and economic pillars of sustainability. Since the idea of functionalism is still valid and many architects around the globe take their inspiration from the functionalist style buildings, for instance, Villa Savoye and Fallingwater, it is therefore important to evaluate the energy efficiency of these buildings. The style, which manifested itself in certain architectural techniques and structural elements, reveals the functional image of the building where the functionalist style in the architectural and sometimes it is also called "
funki
[1] "[16]. It repre-sents the stylistic-historical term, where it overlaps with modernism and is sometimes used synonymously with this. However, often "functionalism" refers primarily to the Scandinavian variant of modernism coupled with a social effort and the welfare state's building. Architects who sought to emulate the foreign role models, especially Le Corbusier's white, cubic houses, restrict design standards, and green roof concept. Considering green roofs in the building envelope has several advantages such as absorbing rainwater, providing insulation, decreasing urban3
air temperature and so on. His works are characterized by flat roofs, white facades, and experiments with concrete, whereas Frank Lloyd Wright’s Fallingwater is built of rock and has flat roofs. Wright takes the nature aspect for the creation of inner spaces. Both architects take nature as the primary subject in the design process [17].
This paper investigates the earlier functionalist style of important buildings through objective evaluation of energy efficiency and daylight analysis of the aforementioned buildings using BIM tools. The authors decide to evaluate some passive energy efficiency parameters such as WWR, window size and position, building shape, orientation and material because the correct use of these parameters are important for passive energy efficiency of a building. This evaluation can be used by researchers in the future in the construction industry to bring these concepts back and be re-use in the new building conceptions, such as low energy buildings and biophilic houses. This will close us a step to mitigate climate change and keep forward toward sustainable development. To achieve the aim of the study, we propose the following research question:
RQ1: In which architectural concepts the passive energy efficiency parameters (WWR, window size and posi-tion, building shape, building orientation and material) are adequately considered and which parameters require to be improved in the future reforming process?
The remaining parts of this research are structured as follows: Section 1 explains the Motivation, Scope, and objective of the paper. In Section 2, the Method for the conduction of the research has been presented. In Section 3 the outcome of the study is presented. Finally, in Sections 4 and 5, the discussion and conclusion and suggestions for future work are presented.
1.1 Motivation, Scope, and objectives
The building style is a reflection of the cultural, spiritual, and material values of a society. Style as a direction in art is a logical continuation of cultural and spiritual changes in society, contributes to the emergence of new social ideas and technical capabilities. With multidisciplinary knowledge in the research area, engineers and the AEC industry need to be a part of architectural concept analysis and take place in this study area. They can have their view regarding the architectural concepts and can put their revaluation of earlier functionalism style and building creators, where sustainability, energy efficiency, and building information modeling. In this situation, they will analyze and criticize the concepts of architecture, which can evaluate the value of each concept and thinking ideas.
Throughout this work, the authors have addressed some limitations, which are set out below, that could impact the results obtained.
The study is limited to the entire building using passive reading of the building's energetic design and daylight analysis of the reference buildings. Based on the energy simulation, the authors focus solely on assessing the principal passive indoor temperature. Furthermore, optimizing the result is not covered in this study. A district heating system is assumed for the installations. Domestic hot water is excluded from the simulation. The effect of the surrounding energy efficiency and daylight is not considered in this study, and the thermal bridge is assumed to be poor.
1.2 Motivation for the analyzed buildings
In this study, the authors chose two examples of functionalism style (Villa Savoye and Fallingwater) for inves-tigation and objective evaluation of passive energy efficiency and daylight. These buildings are renowned single-family houses, built based on two concepts in the golden era of functionalism. These two concepts are pragmatic and organic functionalism. Pragmatic functionalism considers the human being as an efficient activity in spaces and their activity determine the function and form of the spaces [18] see Figure 1. Le Corbusier's idea was that the house should provide fundamental human needs as well as human comfort. However, the organic concept means incorporating the connection from the inside to the outside and the human being must feel satisfaction in
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the living spaces [19]. Thus, these two concepts complete the sphere of efficient functionalism in construction. In addition, there are many other reasons, which are listed below, behind the selection of such houses.
1.
Analyzed buildings are appropriate regarding the style and conformation functional spaces in the house, the arrangement of functions inside the buildings, integration of natural light into the facilities, and effi-ciency of using natural elements in the building. Figure 1 describes how house design factors interact. 2. Analyzed buildings take the simplest form of functionalism, and this may help to provide flexibility in structures.Nowadays, we have to take sustainability into consideration, sustainability is a broad concept that refers to a building's overall ability to provide a comfortable and healthy environment. Additionally, sustainability also means taking people, people's well-being and environment into account in a building design [20]. These are the reasons that we chose these two buildings.
Fig. 1. The interaction among the house conception factors [21]
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Method and models analysis
In this section, the research method and the model analysis are presented.
2.1 BIM-based Passive Energy Efficiency Simulation and Case Study Models
Building Energy Simulation allows us to acquire a detailed prediction of energy use, the temperature within the building as well as HVAC (Heating Ventilation and Air Condition) system of it. In this paper, IDA Indoor Climate and Energy (IDA ICE) has been used for dynamic BES. IDA ICE, the dynamic simulation software, allows us to simulate heat demand, indoor climate as well as energy consumption for the entire building with a high level of detail for each zone [22]. Moreover, a literature study was also conducted to acquire knowledge about the previous and ongoing research as well as collect relevant data for the simulation.
In this study, two examples of previous functionalist buildings designed by two leading architects, Le Corbusier and Frank Lloyd Wright, are used. Le Corbusier is a renowned architect who has introduced its five points of architecture, Pilotis (pillar), free plan, free facade, horizontal window, and rooftop garden. These principles are applied in the functionalist Villa Savoye house located in Poissy, on the outskirts of Paris, France. Le Corbusier tended to use concrete as a construction material because he believed in the brutalist style of architecture.
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Villa Savoye is a two-story building, having a floor height of 3.1 m and a total area of 480 m2. It has a ground
floor, first floor and solarium. The ground floor includes the entrance hall, garage, ramp, maid's room, laundry room, and driver's accommodation. The first floor comprises a living room, kitchen, two bedrooms, master bed-room, private sitting bed-room, etc. The outside of the building is white with a green base and it has little decoration. The piers (Pilotis) bear the roof and floor slab, whereas the walls are not load-bearing. The primary materials used in Villa Savoye are concrete, glass and brick. The floor plans are shown in Figure 2.
Fig. 2. Ground plan and the first level of Villa Savoye, Le Corbusier
The climate in Poissy is warm and temperate and there is rainfall throughout the year. The warmest month is July with an average maximum temperature of 25 ℃, whereas the coldest month is January with an average max-imum temperature of 7 ℃. Figure 3 shows Villa Savoye in different seasons.
Fig. 3. Villa Savoye in different climatic seasons
The second building, which has been opted to use for this study, is Frank Lloyd Wright's Fallingwater function-alist house. Wright designed and built Fallingwater in the rugged forest of Southwestern Pennsylvania. He uses
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rocks, concrete, steel, and wood as a building material for Fallingwater. To maintain the connection with nature, he uses glass in his design [23]. Fallingwater is a three-story building, having a living room, three bedrooms, kitchen, study room, and terraces, see Figure 4. This house is built-in in a 495 m2 exclusive guesthouse which
includes 268 m2 of interior and 227 m2 of terraces. The height of each floor is 2.8m.
Fig. 4. First, second and third floor of Fallingwater functionalist house
The location of the building has a humid continental climate. The average temperature is about 21℃ in July and –2 ℃ in January. Figure 5 denotes Fallingwater in different climatic seasons.
Fig. 5. Fallingwater in different climatic season
The weather data for the energy efficiency simulation of Villa Savoye and Fallingwater is downloaded from the IDA location data center. Since the building's exact location does not exist in the IDA location data center, the nearest location has been chosen for the energy efficiency simulation. The nearest location, for Villa Savoye avail-able in the IDA location data center is Orly, which is 46.4 km away from Poissy and for Fallingwater is Pittsburgh, which is 75.6 km away from the exact location of the Fallingwater. Infiltration air is another input for the energy simulation which is calculated based on the airtightness of 0.5 ACH at a pressure difference of 50 Pa [24]. The pressure coefficients for each face and angle of the purposed buildings are generated automatically from IDA ICE by assuming the building location as exposed in both cases. Since the analyzed buildings are poorly insulated and
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old, the thermal bridges are assumed to be poor. The windows used in both dwellings are single glazing. Since the authors do not have information regarding the doors, the default inner and entrance doors in IDA ICE have been used. Building elements with their respective thermal transmittance (U-value), which is taken from IDA ICE based on material and thickness, U-value for windows and doors are presented in Table 2, refer to Appendices.
Since energy efficiency analysis of the mentioned buildings is of interest, neither a cooling nor heating system has been considered for the proposed buildings. The natural ventilation system is used in the studied buildings to provide fresh air and remove pollutants from the interior volume. The fresh air is supplied to the buildings through leaks and chimneys which are considered on the external wall, refer to Table 3, in Appendices.
The number of occupants in both buildings is estimated based on the Sveby standard. Sveby is a cross-industry program that develops tools for agreement on energy use. It provides standardized user data for the calculation and verification of energy performance. Based on this standard, if the information regarding the number of occupants is unknown in a dwelling, it is possible to estimate the number of people based on the number of dwelling's bed-rooms. According to Sveby for 2- or 3-bedroom apartments the standard values are suggested to be 1.63 and 2.18 respectively [24]. Since both Villa Savoye and Fallingwater have three bedrooms, the three occupants' standard value is considered for both buildings.
In order to evaluatethe passive energy efficiency and daylight for the different locations, the authors have divided the building into three zones namely DAY ZONE, NIGHT ZONE and ZONE 3. Since it is not allowed to have more than one zone with the same name in IDA ICE, we were obliged to subdivide the zones as DAY ZONE_1, DAY ZONE_2, DAY ZONE_3, ZONE 3_1 and ZONE 3_2, see Figure 6 and 7. It is important to men-tion DAY ZONE mainly includes the living rooms and kitchen and NIGHT ZONE comprises bedrooms and bath-rooms, whereas ZONE 3 has spaces where occupants are not spending much of their time such as corridors. Rest of the spaces which are shown in white color in Figure 6 and 7 is terrace.
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Fig. 7. Zone illustration of Fallingwater house
2.2 Simulation process and Setting
The approach and workflow during this paper are shown in Figure 8. To evaluate the energy efficiency as well as carry out daylight analysis of earlier functionalist style buildings, BIM-based Software Revit 2021, In-sight Plug-in in Revit 2021, and IDA ICE are used. The following steps are taken for BES and daylight analysis:
• The Data, drawings in dwg format, and information about the proposed buildings are collected from Archweb [25] and Archinomy [26]
• BIM-model (3D model) is created from the 2D drawings using BIM-based software, Revit. • To perform the energy analysis in IDA ICE, the IFC file format is exported.
• To improve the IFC file quality for BES, the IDA ICE add-on for SimpleBIM is used to validate and prepare the IFC file for use in IDA ICE.
• Perform the whole building energy efficiency and daylight analysis.
When the BIM model is created, the room tags are done for all the functional spaces because it is needed for Building Energy Simulation (BES) and daylight simulation.
Fig. 8. Working process of the simulation labor 1 Data collection 2 Creating BIM Model 3 Preparing BIM Model for simulation 4 Performing Simulation 5 Results evaluation
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As stated earlier, the authors are interested in looking into the main temperature (mean and operative temper-ature) and the amount of illuminance for the entire buildings. Evaluating the indoor temperature variation and the amount of illuminance give us a clear view of which of the functionalist style building could be better in the fu-ture reforming process.
2.3 Daylight Simulation
Daylight is a very important component of architectural design since it plays a central role in the energy con-sumption of a building. Maximizing the use of daylight results in a significant reduction in artificial lighting, which is why it must be taken into consideration in the design process of a building [27]. Daylight more than standard has certain disadvantages such as glare that cause visual discomfort and increase energy consumption. The authors opted to perform daylight analysis based on Leadership in Energy and Environment Design (LEED) because this standard is globally recognized and accepted. According to this green certification system, to acquire LEED day-light credit, there are three options to follow:
Option1: Spatial Daylight autonomy and annual Sunlight Exposure: Spatial daylight autonomy (sDA) checks whether a functional space receives sufficient daylight during standard operating hours yearly. Spatial Daylight Autonym (sDA) is calculated through annual computer simulation. Functional spaces in the building model that attain 300 lux for at least half of the analysis hours count as fulfilling the daylight requirements. As a result, the value for sDA ranges from 0 to 100%. An sDA value of 75% for a functional space is preferred by occupants because they can work comfortably without the need for any artificial lights. Annual Sunlight Exposure (ASE) helps architects and light designers in limiting excessive sunlight for a functional space. Annual sunlight exposure is also calculated through annual computer simulation. For point distribution refer to Table 6 in Appendices.
Option 2: Illuminance calculation: The amount of illuminance shown through annual computer simulation should be between 300 lux and 3000 lux for 09.00 a.m. and 03.00 p.m., on a clear sky day at the equinox for each regularly occupied space, see Table 1 for point distribution.
Table 1. Points for option 2 Percentage of regularly occupied floor Points 55 1 75 2 90 3
Option 3: Measurement: Shows through measurement that Illuminance levels are between 300 lux and 3,000 lux for 09.00 a.m. and 03.00 p.m., both on a clear-sky day at the equinox, for at least 75% of regularly occupied floor area [28]. Point distribution for option 3 is shown in Table 7 in Appendices. In this paper, we chose option 2 for daylight simulation (V4 EQc7 opts2) in Insight Plug-in in Revit 2021. The default threshold is used for daylight assessment (300lux-3000lux). The simulation will show us how much of the functional spaces fulfil the LEED criteria.
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3
Results
In this section, the result of the research is presented. Foremost, the results of the energy efficiency simula-tion are presented for both proposed buildings and thereafter the outcomes of daylight analysis are presented.
3.1 Illustration of Main Temperature in Villa Savoye house
Figure 6 demonstrates the variation of the main temperature (mean and operative temperature) during the en-tire year for the respective zones. The minimum mean air temperature in NIGHT ZONE is -3.7 ℃ whereas the maximum mean temperature is about 31.3℃. Likewise, the minimum mean temperature in DAY ZONE_1 is 4.3℃ and the maximum mean temperature is 31.6℃, see Figure 9. The average temperature of the mentioned zones, for each month can be found in Table 4 in Appendices.
Fig. 9. The graph to the right shows the main temperature for DAY ZONE_1 and Graph to left shows the main temperature
for NIGHT ZONE during the year.
The main temperature for DAY ZONE_2 and DAY ZONE_3 is illustrated for the whole year in Figure 10. The maximum and minimum mean air temperature for DAY ZONE_2 and DAY ZONE_3 is obtained –5.3℃, 32.3℃ and -2.4℃, 33.1 ℃ respectively. The monthly average temperature for the respective zones is shown in Table 4, refer to Appendices.
Fig. 10 . The graph to the right shows the main temperature for DAY ZONE_3 and the figure to the left shows the main
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The mean air and operative temperature for the entire year for ZONE 3_1 and ZON 3_2 is shown in Figure 11. The maximum and minimum mean air temperature for the aforementioned zones are -4.1℃ and 31.0 ℃ and –2.7℃ and 32.0℃ respectively. The average temperature for each moth is also shown in Table 4, refer to Appen-dices.
Fig. 11. The graph to the right shows the main temperature for ZONE_3_1 and the figure to the left shows the main
tempera-ture for ZONE_3_1 during the whole year
3.2 Illustration of Main Temperature in Fallingwater house
The graph to the left in Figure 12 shows the main temperature for the NIGHT ZONE and to the right for DAYZONE_1 during the whole year. Minimum and maximum mean air temperature is –16.17℃ and 33.9℃ for the NIGHT ZONE, while for the DAY ZONE_1 is, –17.5℃ and 34.34℃ is the minimum and maximum mean air temperature respectively. The average main temperature for each moth is show in Table 5 in Appendices.
Fig. 12. The graph to the right shows the main temperature for DAYZONE_1 and Graph to the left shows the main
tempera-ture for NIGHT ZONE during the year
Graphs to the right and left show the main temperature for the DAY ZONE_2 and DAY ZONE_3 see Figure 13. Minimum and maximum mean air temperature for the aforementioned zones is 12.92℃, 30.95℃ and -11.34℃, 33.75℃ respectively. Average temperature for each month for these two zones can be found in Table 5 in the Appendices.
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Fig. 13. The graph to the right shows the main temperature for DAY ZONE_2 and the figure to left shows the main
tempera-ture for DAY ZONE_1 during the year
Figure 11 shows the mean air temperature variation on a yearly basis for ZONE 3. Maximum and minimum mean air temperature for this zone is -13.44℃ and 33.08℃ and the average temperature could be found in Table 5 in the appendices.
Fig. 14. Shows main temperature for ZONE 3
3.3 Daylight Simulation: Villa Savoye
The result of the daylight simulation, which is done based on LEED v4 EQc7 option 2, is shown in Figure 12. Based on this certificate system Villa Savoye is not granted any points because 34% of the regularly occupied floor fulfilled the requirement at the total equinox. However, 57% of the regularly occupied floor fulfilled the requirement at 09:00 a.m., while 22% of the space received daylight below the threshold and 29% above the threshold. In addition, at 03:00 p.m., 34% of the total area received sufficient daylight whereas 24% of the regu-larly occupied floor received daylight below the threshold and 42% of the total area get daylight above the threshold, refer to Figure 15, in Appendices. As shown in Figure 12, the whole building except the Garage re-ceives too much daylight, especially DAYZONE_2 and half of DAYZONE_1.
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Fig. 15. Daylight analysis of Villa Savoye house 3.3 Daylight Simulation: Fallingwater
From the lightning summary, as shown in Figure 15 in Appendices, Fallingwater has not received any point because 45% of the regularly occupied floor fulfilled the requirement at the total equinox. However, 59% of the regularly occupied floor fulfilled the requirement at 09:00 a.m., while 25% of the space received daylight below the threshold and 16% above the threshold. In addition, at 03:00 p.m., 69% of the total area received sufficient daylight whereas 19% of the regularly occupied floor received daylight below the threshold and 12% of the total area get daylight above the threshold, refer to Figure 15, in Appendices. Figure 13 shows that almost the whole regularly occupied space received sufficient daylight.
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4
Discussion
Before discussing the simulation results, the authors analyzed the architectural concepts, pragmatic and organic, based on literature study, regarding the passive energy efficiency and people's well-being. As stated, Le Corbusier implemented his five points of architecture in Villa Savoye. One of his point is considering a green roof for the functionalist style building. The green roof is a passive cooling system that resists the heat penetrated because of solar radiation. Green roofs are suitable both for aesthetic and environmental purposes and they can reduce the inside temperature by up to 3.4 ℃ [29]. In addition, these roofs play a pivotal role in reducing CO2 in the
atmos-phere.
In addition, Le Corbusier's idea considers that a house is a machine for living by applying its modular system, created according to the human anthropometric statement. Moving between home functions has to be optimal and in a usable form. Consequently, he considered human being as an efficient activity in the spaces and their activities in the house determine the form of the space which can help to reduce the energy consumption.
Wright father of organic architecture, brings the outside world into the house and let the inside of the building go outside. He successfully incorporated architecture and nature, the interior with the exterior and nature with space. We can notice that he seeks to connect buildings occupants more closely to nature and create a more pro-ductive and healthier environment for occupants, which is essential for the occupants' well-being.
The energy efficiency and daylight analysis of the earlier functionalist style buildings, Villa Savoye and Fall-ingwater, shows that the main temperature variation in these buildings is not appropriate for living based on sim-ulation, refer to result's section. There are many passive design parameters that can affect indoor temperature variation. Some of these parameters are not properly considered in the architectural design of these functionalist-style buildings and these parameters are analyzed and evaluated in this section. WWR for Villa Savoye and Fall-ingwater houses is 49.8% and 31.3% respectively. However, the best value for WWR in terms of passive energy efficiency, according to Goia's study should be among 30% to 45%. It can be noticed that the WWR criteria are fulfilled for Fallingwater house, but not for the Villa Savoye. The result could be better for the Villa Savoye if the WWR were satisfied.
As stated by Kim et al. [8] the lowest energy load is achieved when the midpoint of the windows is positioned in the middle of the wall. Both in Villa Savoye and Fallingwater the window center is not located in the center of the wall and the size of the windows is also big. This could also have a negative impact on the indoor temperature variation.
Both analyzed buildings oriented toward the Southwest. In Villa Savoye house, windows are positioned almost equally in all orientations but in Fallingwater most of the window's surface is oriented toward Southwest. Miomir et al. [11] showed in their research that the best orientation of the building is where the biggest surface of the window oriented toward the South. It indicates that the Fallingwater functionalist style building is not oriented in the most energy-efficient orientation. However, in Villa Savoye house, building orientation does not affect the heating energy demand, because as stated windows are placed in all orientation. Furthermore, Villa Savoye has a rectangular shape whereas Fallingwater possesses a complex shape. However, as stated in [9], a square shape is the best building shape in terms of heating energy consumption. Neither Villa Savoye nor Fallingwater has a square shape, to contribute to the energy efficiency of these buildings. The daylight analysis shows that almost both buildings are well illuminated by natural light. Nevertheless, as shown in Figure 12 and 13, some zones such as a part of DAY ZONE_1 and entire DAY ZONE_3 in Villa Savoye, and DAY ZONE_1, NIGHT ZONE and DAY ZONE_3 in Fallingwater receives too much direct sunlight, because both building lack external shading device. This causes glare which creates visual discomfort for occupants. Moreover, too much direct sunlight causes over-heating in these buildings. As shown in Figure 14 the maximum temperature reaches around 35 ℃ in July for both buildings.
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To control the amount of daylight in zones that are affected by glare the external shading devices such as eaves, awnings and verandahs can be installed, because these devices play a pivotal role in reducing unwanted solar heat gain, especially in cooling-dominant and temperate climates. Both in Villa Savoye and Fallingwater large windows and glass facades are used to maintain a relationship with nature, but as stated these windows and glass façade lack external shading devices which is why too much direct sunlight is coming into the buildings and causing overheating in summer.
Fig. 17. The graph to left shows the mean air temperature for Villa Savoye and to the right for Fallingwater in July Since the material is a part of the concept in the studied buildings, as an example, the authors decided to discuss the impact of external wall material on passive energy efficiency. As shown in Table 2 in Appendices, the exterior wall construction for Villa Savoye house is brick with plaster on both sides which has a U value of 1.87 W/K m2
where for Fallingwater house is a rock which has different thickness, and the U values range from 3.297 to 4.545 W/K m2. Based on Swedish standards the U value for the exterior walls should be 0.18 W/K m2. Wang et.al. [26]
found that the external wall stands for >40% of the whole building energy consumption. The lower the U value is the better the exterior wall becomes in terms of energy efficiency. In general, the material used for both buildings is not appropriate in terms of passive energy efficiency and it is therefore important for the designers and architects in the AEC industry to consider material having a good U value for the future reforming process.
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Conclusion
This paper presented evaluation of earlier functionalist buildings regarding energy efficiency and daylight. As a case study, the authors chose Villa Savoye and Fallingwater, two earlier functionalist style buildings. BIM-based software Revit 2021, IDA ICE version 4.8 and simpleBIM were used to evaluate the proposed buildings. Villa Savoye and Fallingwater are located in various geographical locations, France and the United States, but these buildings are roughly similar in nature terms in architectural spaces. Since the exact location of the buildings does not exist in IDA ICE, the nearest locations to the analyzed buildings were chosen. The effect of surrounding on passive energy efficiency and daylight has also been overlooked in this research. These factors could likely influ-ence the results achieved. Results of the energy simulation have shown that the operative and mean air temperature variation in Villa Savoye and Fallingwater functionalist houses are not appropriate for living for the entire year. Moreover, the daylight simulation indicated that both buildings received sufficient daylight which reduces the use of artificial lights and therefore contributes to energy efficiency. Nonetheless, as illustrated in Figures 12 and 13 a
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part of the regularly occupied floor received too much direct sunlight which causes discomfort for occupants and overheating in buildings.
This study concluded that in the pragmatic functionalism concept the building orientation, considering green roof and the relation between functional spaces are acceptable, whereas in the organic functionalism WWR, and incorporating the connection between the inside and outside environment are suitable in terms of energy efficiency. Furthermore, parameters, which are needed to be improved, in the future reforming process, for both concepts are building shape, position and size of the window, add the external shading device to improve daylight and building materials. The suggested improvement will drastically enhance the indoor temperature variation and daylight in the mentioned concepts. In closing, it can be stated that all the appropriate design parameters as stated above for both concepts can be combined and used in the future reforming process.
During the life cycle of this work, many ideas have emerged that could be used as continuous studies. One of the interesting ideas for future research would be to apply the energy-saving measures suggested in this paper as well as consider the effect of surrounding and evaluate the main temperature and daylight for these two concepts and similar style houses.
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Appendices
Table 2. Building elements thickness wither their respective U value. Building elements
Villa Savoye U-value (W/K m2) Fallingwater U-value (W/K m2)
100mm Brick wall with 1.5 cm plaster on both side 2.759 150 mm Stonewall 4.545 250 mm Stonewall 3.947 350 mm Stonewall 3.488 150mm Brick wall with 1 cm plaster on both side 2.229 400 mm Stonewall 3.297 500 mm Stonewall 2.970 200mm Brick wall with 1 cm plaster on
both side 1.870 550 mm Stonewall 2.830
600 mm Stonewall 2.703 650mm Stonewall 2.586 810 mm Stonewall 2.273 1300 mm Stonewall 1.657 200 mm concrete
floor with 1cm plas-ter on both side and flooring on the top side
3.378
200 mm concrete floor with 1cm plaster on both side and flooring on the top side
3.378
200 mm concrete roof topping with 5 cm brick
2.270 200 mm concrete roof top-ping with 5 cm stone
Inner Door 2.194 Inner Door 2.194 Single Pane Window 5.800 Single Pane Window 5.800
Table 3. Shows number of leaks and chimneys considered in both buildings
ZONES Villa Savoye No. Leak/ Chimney Leak area m2
NIGHTZONE 4 0.01 DAYZONE_1 5 0.01 DAYZONE_2 1 0.01 DAYZONE_3 3 0.01 ZONE 3_1 0 0.01 ZON3 3_2 0 0.01 ZONES Fallingwater No. Leak/ Chimney Leak area m2
NIGHTZONE 4 0.01 DAYZONE_1 5 0.01
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DAYZONE_2 1 0.01 DAYZONE_3 3 0.01 ZONE 3_1 0 0.01 ZON3 3_2 0 0.01
Table 4. Shows average main temperature for the Villa Savoye
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Table 6. Points for Option2
Table 7. Points for Option3
