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Z. Haghighi

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Authored

Architectural Photovoltaic Application

Doctoral thesis (2022) - Z. Haghighi

Today, photovoltaic technology is one of the fastest-growing fields of technology and is becoming the lowest-cost option for electricity generation in the greatest part of the world. Based on IEA projection, the number of households relying on solar PV grows from today’s 25 million to more than 100 million by 2030. Based on this projection, we must use all surfaces on and around buildings of an entire city to absorb solar radiation and transform it into usable electricity (or useful heat). However, current attempts to harness these potentials within the built environment leaves much to be desired. It is readily apparent that the current roof-top installation approach is neither aesthetically appealing nor technically efficient and consequently not sustainable, long-term, and reliable. Back in the 1990s, the Integration approach was introduced to address these issues. However, the introduction of this solution has neither increased popularity nor helped with untapping the solar energy potentials within the built environment. The fundamental problem addressed in this dissertation is the lack of appropriate guidance and well-structured knowledge about the approaches and considerations which should be deliberated in the design and decision-making process for deploying PV technology in architecture. The overarching goal of this research is to promote the use of PV technology in the built environment while being thoughtful of the symbiotic and functional relationship between the technology and the urban fabric. Specifically, it aims to support the decision-making process required for the adoption and development of photovoltaic products in the built environment. This thesis builds upon the interrelations between the concept of Integration, design decisions, and technological decisions. As the starting point, we looked into ‘integration’ as an alternative approach to the existing addition or attachment of PV into buildings. To do so, we explored given definitions and requirements outlined for the concept of Integration within the context of the application of PV in building architecture. In existing literature, integration is described as the solution for wider adoption and acceptability of PV in the built environment and defined as situation where PV module replaces a building material in a building. However, our findings show that integration does not presume photovoltaic products to be used as part of the construction material and serve a secondary or tertiary function. Furthermore, it highlights under the definition of Integration, the PV system can still be part of the architecture and remain a building service and perform a singular function as a renewable energy generator. In the next step, we looked into how architects have used PV technologies in buildings. We shortlisted 30 projects and categorised them based on those design decisions that made them different from one another. We highlighted that these projects could be categorised based on decisions made on (i) visibility of PV system in the building architecture, (ii) mounting strategy and structural connection of PV panels and building, (iii) the customisation level of PV module, (iv) the building fabric used, and (v) the role of PV in the building system. Subsequently, 30 architects were interviewed to study their experiences and perceptions about the architectural application of photovoltaic. In this study, we approached two groups of architects: one with experience of using PV technologies and the other with no relevant experience. Based on the input received, we witnessed three types of motivations for using PV technologies in architecture projects: the first type was related to external incentives that drive the project (e.g., NZEB), the second type was rooted in the architect’s interest in environmental-friendly and climate-responsive technologies in buildings, and the final one is a communicative gesture in which PV technologies was used as a symbol of sustainability mandated by the project owner. The findings also shed light on the differences in opinions between architects who had already applied PV technology and those who had not. Unlike those with experience working with PV technology in their previous projects, who believed that working with this technology is not complex and problematic, the group with no experience believed that working with PV technology is challenging. Furthermore, a common opinion between the two groups was the need for more versatility in colour, transparency, size, and reflectivity of module products. In the following step, we looked into the existing PV technologies and explored their its various features and potential in architectural application. The findings highlight that the first-generation technologies (c-Si) are the most advanced and can perform better for building applications. However, the physical flexibility of this technology for customisation on the cell level remains limited. In the second-generation technologies, higher temperature tolerance is an advantage for them to be compatible in situations where double-sided ventilation is not possible. Even though most of the second-generation technologies are already lightweight and flexible, and although it they have some level of transparency in contrast to the first generation, their automated production lines make customisation of size and shape fairly difficult. The third-generation technologies received more attention because they offer lower production costs, reduced environmental impact, and a relatively higher efficiency compared to the first and second generations. This makes them an interesting option for architectural application, even though their limited service life expectancy remains an important disadvantage. Aside from the criteria mentioned for comparing these alternatives, many other factors are involved in finding the most suitable PV technology for a certain application. The architects interviewed highlighted these criteria. So, we looked into advanced decision-making methods to see if such methods can be applied in the selection process of PV technology. Through the development of a pilot tool on multi-criteria decision making method, analytic hierarchy process, and test within a concept development project, we concluded that such a method can be very helpful in finding the most suitable technology for a certain application. In the final stage, we worked on development of new concepts for the application of PV technology in buildings as based on several reports reviewed and on results of interviews, it became apparent that existing PV products cannot fulfil current market demands and consequently the sustainability targets. We then examined the R&D processes of these projects, which showed that despite the differences in scope, objective, and nature of the concepts, several similarities could be articulated into a generalised concept development process. According to this analysis, the R&D process before the commercialisation phase can be divided into 7 steps, namely (i) scoping and definition (ii) exploration (iii) concept development (iv) proof of concept (v) optimisation (vi) application design development (vii) prototyping. Overall, the findings of this research can be summarized in three recommendations: first, integration in this context as perceived and defined in the standards and manuals cannot be seen as a comprehensive approach to include all the architectural styles and approaches to use PV technologies in buildings. Therefore, rethinking its definition and requirements is essential. Secondly, suppose we want PV technology to become a default building service, we need to leave it to architects to accommodate it within the design concept as they wish, and the PV industry should not try to impose this technology on architecture. And lastly, we need to develop a new discipline around the design and engineering of energy-producing buildings. We need to train and equip future practitioners with insight, know-hows, and tools to use the ultimate solar energy potentials to produce energy, store, and utilize the generated energy on-site. @en

Architectural Photovoltaic Applications

Lessons Learnt and Perceptions from Architects

Journal article (2021) - Z. Haghighi, Mahboubeh Angali Dehnavi, T. Konstantinou, A.A.J.F. van den Dobbelsteen, T. Klein

Researchers have reported that despite technological development in photovoltaic technology and substantial cost reduction, there is still a narrow interest in architectural photovoltaic applications (APA). Lack of interest is correlated to various bottlenecks, and one of them is ...

Photovoltaic chimney

Thermal modeling and concept demonstration for integration in buildings

Journal article (2019) - J.C. Ortiz Lizcano, Z. Haghighi, Sander Wapperom, C.A. Infante Ferreira, O. Isabella, A.A.J.F. van den Dobbelsteen, M. Zeman

This work presents the concept of a photovoltaic (PV)-powered solar chimney. We modeled and experimentally studied the integration of a PV system within a naturally ventilated façade (NVF), attempting to use the inherent cavity as a ventilation channel to transfer heat. Thermo ...

Contributed

Thermal and Electric Performance of PV/T Solar Chimney System

Master thesis (2020) - K. Vattis, O. Isabella, J.C. Ortiz Lizcano, P Luscuere, P. Manganiello, Z. Haghighi

The residential and service sectors are responsible for the 39% of the total energy consumption. 80% of this energy is used for heating purposes. Achieving nearly zero energy buildings is a major goal for the near future. The design of an integrated electrical and thermal system can substantially help to reach such objective. The façade is the biggest area of a building and could be utilised to convert incident solar energy to electrical and thermal energy. In previous work (2019), the combination of building integrated PV modules with solar chimney on a façade was investigated to study its energetic performance. One of the main findings was that using the thermal energy from the photovoltaic modules on the air inside the cavity of the chimney is not possible due to its low quality of heat. It was concluded that the utilization of heat could be better by using auxiliary systems, like photovoltaic thermal systems for water heating. The aim of this work is to create a computational model to calculate the thermal and electrical performance of PV thermal (PV/T) modules combined with a solar chimney. Two new designs for better heat utilization where considered and compared. The first design is for the PV modules to be installed at the front of the solar chimney with fins (Fins design) and the second design is to couple the PV modules installed on the wall inside the solar chimney with water pipe system (Water pipe design). These designs are also compared with the same configurations but without the thermal systems (No fins & No water pipes designs). In addition, two new strategies are introduced to improve the performance of the model. The first strategy is the optimization of the solar chimney openings with respect of time for the highest power generation. The second strategy is the variation of the water mass flow with respect to time for highest water-thermal energy and optimum cooling of the PV cells. The model was developed in MATLAB and it is based on 2D finite difference transient implicit method. To reduce the computational time, the density of the nodes varies in respect of temperature gradient. In addition, secondary models were created to increase the accuracy and sensibility of the model such as water tank and water pump models. The models were studied for a building in Delft, Netherlands, and the scale of the chosen system is 10m2. It is concluded that Water pipes design provides the overall best energetic performance mainly because of the high water-thermal energy with yearly energy efficiency of 64.3%. However, the best electrical performance is observed from the Fins design and the best air-thermal performance from the No water pipes design.

Photovoltaic and Heritage

Towards the energy transition of the building environment

Master thesis (2019) - I. Tzetzi, A.A.J.F. van den Dobbelsteen, W.J. Quist, Z. Haghighi, F.L. Hooimeijer

Reaching a neutral use of energy in the building environment is challenging. That is because, as the population expands, so does the energy consumption. Considering that the building environment is accountable for 40 percent of energy consumption and 36 percent of total CO2 emissions, the building sector has to conform with specific guidelines and targets, in order to reach neutral energy use. Newly constructed buildings are already targeting better energy performance. However, more than one fifth of European building stock has been built before 1945, and together with low renovation rate in Europe, heritage buildings are struggling to become part of the new energy reality. In order to complete the energy transition, every sector of building environment should commit on energy saving and producing interventions. On one hand, by renovating heritage building stock energy is saved and buildings are performing better. On the other hand, it is challenging to apply energy production interventions in such buildings in order to balance the energy demand. This is the reason why, the current research is focusing on how photovoltaic technology could be applied on heritage buildings, without compromising their architectural character. The application guidelines, which are going to answer the latter question, are going to be tested on a heritage case study in Greece. Moreover, the legislative framework for energy transition is going to be described with the purpose to explore the extension of the guidelines, since they are covering all sectors of human activity. Additionally, the building stock in Greece is being presented and how the European legislative framework is applied in this country’s concept. What is more, photovoltaic technology is going to researched in depth, specifically how the photovoltaic cells are producing and how do they produce energy. In order to get more explicit about solar interventions on heritage cases, such as where is the best place for the application and why. In addition to that, more criteria for suitable solar application on heritage are going to be researched, such as color, transparency, size and functionality. After the literature research on both heritage culture and photovoltaic technology, and also the applied version of them in reference buildings, a list of design requirements has formed. Therefore, the only way to test if these guidelines could be used for photovoltaic application in a random building, then it could be very valuable to similar future interventions. Thus, a heritage case building in Greece, specifically in the city of Florina of north-western Macedonia. Regarding the design process, up next, the photovoltaic application is going to be analyzed based on the design requirements of the technology upon heritage and the specific demands of the building case. Supplementary to design guidelines, a matrix is formed in order to present all the different options for the interventions. By the end of the matrix, two energy scenarios are forming in order to perform the application in situations as close to reality as possible. Regarding the design, public opinion upon energy interventions is very valuable, and especially when it comes to solar application on heritage buildings. Moreover, the acceptance of similar interventions is going to be discussed. In addition, and in order to have specific overview about public acceptance in the local community of this research case study, a questionnaire is going to be conducted. The results are going to be presented and the public’s influence is going to be examined. Ultimately, the final design proposal for the case study is going to be demonstrated and the different applications are going to be analyzed. Finally, an overview of the design proposal is being inspected, as far as it concerns the building itself and the urban environment in total. To sum up, general conclusions re going to be presented and also the limitations of the research itself. A few suggestions are additionally to be explored for investigation of future possibilities on the subject.

Investigation and implementation of the PV-Chimney'system on building emvelopes

Master thesis (2019) - A. Lysandrou, A.A.J.F. van den Dobbelsteen, R.M.J. Bokel, Z. Haghighi, Martijn Stellingwerf

This study refers to the PV/T-chimney system, an innovative system that combines two solar systems, a Trombe wall system and a PV/T system in order to gain more energy per square meter of application. The research analyzes the impact of the PV-chimney system on the energy performance of residential high-rise buildings and the architectural integration of the system as part of the facade. Different facade design alternatives, which investigate different facade patterns and their limitations in terms of functional and practical issues, provide a categorization of different ways of its use. Based on that, for each architectural category, by the help of energy simulations, a multicriteria analysis of the system is done. The aim is to understand the behavior of the proposed PV-chimney system under different geometrical characteristics in different climate conditions, in order to find the most optimal parameter combinations in terms of performance. In the second part, having as case study the Europoint Towers, in Rotterdam, a detailed facade design of PV/T-chimney is proposed based on the findings of the architectural and multicriteria analysis. This design, was developed in order for the system to adapt in the climate of the Netherlands, where the case study building is located as well as the climate of Hungary, where, it was constructed in 1:1 scale under the framework of Solar Decathlon 2019 competition, which took place in Hungary. In Hungary, an experiment of the system was conducted, in order to test the efficiency of the Photovoltaics under high temperatures and the potential use of this system for ventilation purposes. The results of the experiment indicate the viability of the simulations and underline the possible future improvements of the system for higher energy performance. According to the experiment measurements and the simulations, a comparison of the proposed system with conventional products proves that there is a reduction of the PV efficiency due to high temperatures. Thus, there are energy losses in the operation of the PVs. However, the electricity losses are depreciated by the thermal gains of the system, which give a final positive energy sign to the system.

The Transition

Design and engineering of a sustainable solar carport for the 'Nederlandse Spoorwegen'

Master thesis (2019) - J.A. Dijkema, A.A.J.F. van den Dobbelsteen, P. Eigenraam, Z. Haghighi

The energy transition is a hot topic, businesses also need to think about manners to transition to sustainable energy. Within this graduation the- sis, a stakeholder is involved named the ‘Nederlandse Spoorwegen’, in short NS. The stakeholder has the ambition to make their station’s en- ergy neutral. To achieve this, electricity generating assets needs to be implemented on every asset they own. One of these assets is the P+R parking plots near stations. An easy way of implementing solar into the parking plots is by integrating the solar panels into a carport structure. Current solar carport designs which have been constructed so far, are purely focusing on the aspect of generating the maximum amount of electricity and neglecting the aspect of design. The NS has the ambition to make the carport design sustainable in appearance and material use. Besides the sustainable appearance of the design, the design should be applicable in every P+R parking plots. This results in a modular sustain- able carport design that is orientation independent. For the design, a solar cell technology was needed. Three generations of solar cells were found in literature, but the third generation was not further researched since this generation isn’t commercially available yet. The remaining two generations of solar cell technologies (1st and 2nd generation) were researched on the following topics; performance, de- sign, and sustainability. The information found in this literature research directly fed the multi-criteria analysis (MCA) method called the analyt- ical hierarchy process. With this MCA method, polycrystalline silicon solar cell technology was selected to be the best suitable for the design. Another downside to the current solar carport designs is that these de- signs don’t fully exploit the structural capabilities of the solar panels. In the ﬁnal design, a connection is designed and analyzed to exploit the structural capabilities of the solar panels, whilst still keeping the trans- parent nature of the solar panels intact. The ﬁnal design features recycled rail tracks in the structure of the car- port. Besides being made from high-grade steel and the shape of the rail tracks suits their integrating into the structure, the direct link to the stakeholder was also recognized as a beneﬁt for the ﬁnal selection of this material. To further enhance the sustainable appearance/function of the carport, a green wall is implemented to absorb the rainwater. Thus, im- proving the water absorption in the asphalt dominated landscape of the P+R parking plots. In particular, the design of the sustainable solar carport for the NS is analyzed on solar radiation performance and structural performance (on carport scale and on connection scale). To gain an understanding if the new connection is beneﬁcial on a carbon footprint scale, the newly designed connection is compared to a standard aluminum transom and mullion system.