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  • 1.
    Andersson, Victor
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Väderprognosstyrda värmesystem i byggnader: En jämförelse mot traditionell styrning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this essay is to investigate how forecast control can affect the energy consumption and the top effects for heating compared to the traditional control system in facilities with different building structures. In 2013 were the energy consumption 80 TWh for the heating and domestic hot water in resident buildings and facilities. This corresponds to 55 % of the total energy consumption within the building sector and facilities represent 28 % of the buildings. This indicates that there is room for efficiency for the heating systems in facilities.Demands from new directives for stricter energy consumptions for buildings are going to be established in the Swedish regulations and 19:th of June 2018 were the new amending directives published which need to be established in the Swedish regulations latest 10 March 2020. The demands on the buildings is pushed further and further. It is getting more difficult to reach the requirements from BBR and even more difficult to reach the requirements from environmental certifications like Miljöbyggnad. Therefore, it is important with detailed solutions that is able to lower the energy consumptions for the heating systems.A reference building has been used and created in the simulation software IDA ICE with three different building constructions to compare forecast control against the traditional control system. One with a large U-value and low amount of thermal mass, one with a smaller U-value and a low amount of thermal mass and one with a smaller U-value and a high amount of thermal mass.The centrally controlled forecast control is tested against the traditional controlled system for each building structure. Traditional controlled systems in facilities is normally using thermostatic valves, due to the lack of sustainability and the lack of maintenance the control systems are also tested without the thermostatic valves.The results for the forecast control indicate on an increase for the energy saving by 3.4 % without the thermostatic valves and an increase by 2.7 % with the thermostatic valves. The top effects can be improved with forecast control by 33 % without thermostatic valves and by 15 % with thermostatic valves. These improvements were made for the building construction with high amount of thermal mass. It is possible to argue for benefits with forecast control if it is installed in a heavy constructed building with regard to the decreased top effects. It is more difficult to argue for the benefits with regard to the energy consumption. Large benefits were found with in local control, especially for buildings with large U-value and low amount of thermal mass. The result indicated on an improvement of 30 % for the traditional control with thermostatic valves and of 28 % for the forecast control with thermostatic valves compared to the scenario without the thermostatic valves.Knowledge about the building characteristics has a significance for the choice of control system. According to the results forecast control may be a benefit with regard to the top effects if it is a heavy building construction. Regarding the energy consumption is the best strategy to carefully adjust and maintain the current traditional control system.

  • 2.
    Björk, Folke
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    af Klintberg, Tord
    Extra material till:  Simhallar – ett övergripande perspektiv på teknik, hälsa, beständighet och ekonomi: Från projektet:Nordic Built: Evaluation and Renovation of Ice Halls and Swimming Halls - NERIS2019Collection (editor) (Other (popular science, discussion, etc.))
    Abstract [sv]

    Till rapporten: Simhallar – ett övergripande perspektiv på teknik, hälsa, beständighet och ekonomi finns en del extra material som stöder rapporten men som är svårt att komma åt. Vi har därför beslutat att göra materialet tillgängligt på detta sätt för att den som är intresserad av simhallar ska kunna få en egen djupare insikt.

  • 3.
    Björk, Folke
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    af Klintberg, Tord
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Simhallar – ett övergripande perspektiv på teknik, hälsa, beständighet och ekonomi2019Report (Other academic)
    Abstract [sv]

    Simhallar har olika problem, avseende både hälsoaspekter och beständighet. Dessutom förbrukar simhallar stora resurser ur ett ekonomiskt perspektiv. Neris-projektet har skaffat sig ett helikopterperspektiv på simhallars olika delar och risker och många av dessa risker orsakas av desinfektionen av badvattnet. I dagsläget så syftar hygien, rengöring och desinfektion främst till att hålla mikroorganismer på låga nivåer och det är viktigt att hygienen samt rengöringen optimeras. När det gäller desinfektionen av badvattnet så har klorering används under mycket lång tid, metoden är mycket effektiv för att döda de flesta mikroorganismerna, men orsakar även lungbesvär och korrosion som förkortar hallarnas livslängd.

    Denna rapport har inte hittat några vetenskapliga artiklar som belägger vilka kloreringsnivåer som bör tillämpas i en simhall. Dessa nivåer förefaller basera sig på tradition och på ett kunskapsläge då lungbesvär och korrosion inte beaktades. Det är tveksamt om exempelvis Folkhälsomyndighetens gränsvärden för klorhalter är grundade på ett spårbart sätt i vetenskapliga arbeten, som de bör vara.

    Det vore önskvärt att vetenskapligt undersöka vilka klornivåer som är tillräckliga och göra en sammansatt optimering med avseende på mikroorganismer, lungbesvär och korrosion.

    Blått ljus i simhall och fotokatalys i reningsverk  reducerar behovet av klorering, vilket har visats i Enskedehallens babysim. Vidare är det möjligt att få en bättre beskrivning av den mikrobiella situationen i badvatten med hjälp av partikelmätning, vilket kan minska de bakteriella riskerna i en simhall.  Dessa metoder bör bli föremål för vidare forskning.

    Hur stor är den sammanlagda korrosiviteten i en simhallsbyggnad? Det finns olika faktorer som samverkar i en simhall, som hög temperatur, högt fuktinnehåll i luften, klorider, underklorsyrlighet, och säkert fler faktorer, som inte är identifierade. Det är en forskningsuppgift att utföra olika metodtester för de olika delarnas korrosiva del och samverkande korrosivitet. Det finns inga rutiner för att avlägsna klorider som hamnat i simhallsrummet. Det vore bra att utarbeta sådana rutiner.  

    Det kan finnas ett motsatsförhållande mellan beständighet och energibesparing. Exempelvis så sparas energi om ett minimum av vatten blöder av, men detta ökar kloridkoncentrationen i badvattnet. På samma sätt ökas kloridkoncentrationen i simhallsbyggnaden om luften får gå i rundgång med ökad korrosionsrisk som följd.

    Avdunstningen är mycket energikrävande och det vore då intressant att minimera ventilationen över vattenytan. Den ventilationen är i dagsläget behövlig för att få bort skadliga gaser, exempelvis kloroform och trikloramin, som är en följd av kloreringen. Om klorering kan minska så kan även ventilationen över vattenytan minimeras, med energibesparing som följd

    Simhallsprojektet i Stad x riskerar att bli mellan 50 och 100 miljoner dyrare än vad som beräknades i förstudien. Förstudien har visat sig att vara optimistisk med avseende på fördelar, men svag med avseende på kostnader. Detta har försatt staden i en ekonomisk knipa, som riskerar att exempelvis materialval blir sämre med kortare beständighet som följd.. Förstudier inför ett simhallsbygge kan bli bättre. Det vore till exempel bra att göra en tredjepartskontroll med avseende på intäkter och kostnader.

    En kommun skulle kunna etablera en expertgrupp av kunniga tekniker och ekonomer som skulle kunna beakta och besluta över tekniska renoverings-, underhåll- och driftsfrågor. Detta vore en strategisk kunskap, som vore bra att ha in house.

  • 4.
    Engström, Olle
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Optimization of fluid-based heat-recovery systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report aims to investigate how fluid-based heat-recovery systems for ventilation can be optimized. A high proportion of existing systems operate at lower efficiency than possible, and thus do not reach their full potential in terms of energy savings. The aim of this report has been to find out why, to identify which parameters affect the efficiency of such systems, and to develop a general methodology for optimization. As a method for execution, a literature study and field experiments were chosen. The results from the literature study showed that dimensioned efficiency, fluid flow in the circuit and degree of contamination of the system were important parameters that greatly affected performance. The field experiments largely confirmed this, but also showed that an implementation of the theoretically optimal fluid flow is not always beneficial to the performance, but higher flow should always be considered. The results also indicated a correlation between the fluid flow and the convective heat-transfer coefficient (U-value) in the heat exchangers. A methodology for optimization is presented in the discussion section. As a suggestion for further research, two possible directions are proposed - the potential of cleaning and the effect of the fluid flow.

     

  • 5.
    Härer, Simon
    et al.
    Faculty of Engineering, Reutlingen University, Reutlingen, Germany.
    Nourozi, Behrouz
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Wang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Uponor AB, Västerås, Sweden.
    Ploskic, Adnan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Bravida Holding AB, Hägersten, Sweden.
    Frost reduction in mechanical balanced ventilation by efficient means of preheating cold supply air2019Conference paper (Refereed)
    Abstract [en]

    This study has focused on evaluating the financial potential of wastewater and geothermal heat recovery systems in a multi-family building. The recovered heat was used to improve the performance of mechanical ventilation with heat recovery (MVHR) system during the coldest days in central Sweden. The main issue, which was targeted with these solutions, was to reduce frost formation in the system and hence increase its thermal efficiency. By looking at the life cycle cost over a lifespan of 20 years, the observed systems were being evaluated economically. Furthermore, statistical analyses were carried-out to counter the uncertainty that comes with the calculation. It was found that the studied wastewater systems have a high possibility of generating savings in this period, while the one fed by geothermal energy is less likely to compensate for its high initial cost. All designed systems however, managed to reduce operational cost by 35-45% due to lower energy usage.

  • 6.
    Jerome, Adeline
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Integration of LCA into the building design process2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The required estimation of performances of a building cannot be limited to its energy efficiency anymore. Environmental issues are rising concerns into national policies. However, information about construction products is still segmented into several distinct databases: the construction company gathered data for its design process into private pricing databases while environmental declarations from manufacturers are available in a public database. The interconnection of the different information about the same product is difficult because of the difference of data formatting and representation.

    The objective of this project was to provide first tools to facilitate this interconnection between the design process of the company and environmental data, considering incoming requirements from the new thermal regulation of 2020. This led to the creation of a SQL environmental database, based on environmental declarations, more adapted for statistical analysis than a document-based database. Specific data management functions were also developed to homogenise unit representation and to spot product performances for the purpose of multi-criteria analysis of products

    Finally, an estimation of the distinctiveness of products through a selection of key words was tested. The comparison of lists of words provided good performances for their classification into a limited number of lots. But it is not sufficient to identify items that can be related to the same construction product. So further works is needed into the creation of a semantic metric model of construction vocabulary.

  • 7.
    JImenez Lopez, Carlos
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Performance analysis and validation of high-temperature cooling panels in passive geothermal system2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High Temperature Cooling, HTC, is a thermal conditioning strategy, which aims to reducemixing and transfer heat losses. Cooling capacity strongly depends on heat transfer coefficientsand offers a great response and several advantages in terms of efficiency and sustainability.Among the advantages, there is evidence that HTC offers an increment of energy efficiency ofHVAC systems, provision of healthier and more comfortable indoor climate and provide widepotentials for the applications of renewable. This principle leads to a higher energy efficiency ofwater-based radiant cooling systems.This paper intends to focus on the research of the thermal capacity and performance of a newalternative. This is where Cooling Radiant Ceiling Panels, CRCP, becomes a major innovationwithin the sector and begin to take on certain relevance. The cooling capacity curve of thisparticular CRCP panels has been only measured in an idealized room environment according toDIN EN 14240. Thus, further studies of this key parameter through climate chamber testingand Computational Fluid Dynamics simulations, CFD, are necessary. CFD particularly focuseson fluids in motion, their behavior and their influences in complex processes such as heat transfer.The fluid motion can be described through fundamental mathematical equations and it isbecoming widely used within the building sector.Two different cases are going to be investigated. The first case will determine the mostoptimal peripheral gap to enhance cooling performance through Natural Convection, NC. Thisstudy states the existence of a peripheral gap around the panels has proven to be inefficientin terms of enhancing natural convection in the climate chamber. The second case is aboutcalculating the cooling capacity as a function of the internal heat loads. The cooling capacity ofthe CRCP panels followed an expected behavior. The R-squared factor of the linear regressionwas found to be 0.986, hence, it does not affect the performance of the CRCP panels dependingon the inclusion of the IHLs.This thesis provides the necessary information for the implementation of CRCP panels anddifferent possible operating environments, including considerations, limitations and recommendationsfor future implementation of this strategy.

  • 8.
    Kharazmi, Parastou
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Durability Evaluation of Reinforced Glass-Flake Polyester Material Used in Rehabilitation of Sewer Lines in Buildings-Dataset2019Data set
    Abstract [en]

    This dataset includes water absorption measurement data to support research findings in the article: ”Durability Evaluation of Reinforced Glass-Flake Polyester Material Used in Rehabilitation of Sewer Lines in Buildings" with the following abstract: The aging of sewer infrastructure in buildings is an ongoing problem, and total replacement of deteriorated pipelines is a difficult and costly process. Currently, different materials and methods are in use in alternative rehabilitations technologies. This work was conducted to study one of these materials, which is a glass-flake reinforced polyester polymeric system, during artificial aging to provide a better understanding of the material’s performance under operating conditions when it is regularly exposed to degrading factors such as high temperature and water. Aging of the material was studied in the lab by monitoring changes in the material when it was exposed to different temperatures (20°C, 40°C, 60°C and 80°C), both when immersed in water and under dry conditions. Changes in the material during aging were monitored by conducting different tests, including thermal and mechanical analysis, water absorption and microscopy. The results showed that a combination of aging in water and high temperature had a greater effect on the material compared to aging at high temperature in dry conditions. Mechanical testing showed that the flexural modulus and strength decreased by 50-58% and 42-58% respectively for material immersed in water for two months when compared to the material exposed to similar temperatures in air aging. Moreover, the differences between the flexural modulus and strength of the materials exposed to wet and dry conditions were higher under longer exposure times and exposure to higher temperatures. It was observed that the reduction in the flexural modulus and strength after six months of water aging was more significant at 80°C, where the decreases were 77% and 72%, respectively, in comparison with the material subjected to air aging. Thermal analysis revealed more changes in the material at 80°C than at other exposure temperatures, while water absorption results showed a larger and more rapid water uptake at higher temperatures.

    Although the measured properties were affected significantly when immersed in water at high temperatures, the material showed acceptable properties at lower exposure temperatures, such as 40°C, during a few months of artificial aging. Considering that the liner material bonded to the pipe is not immersed in water during operation but rather comes into contact with water only from one side, that the average temperature inside sewer pipes in buildings in Sweden is known to be 40°C and that the installed material, particularly in gravity sewers, will not be exposed to water constantly, it can be concluded that the material should work as expected during its service life. 

     

  • 9.
    KHARAZMI, PARASTOU
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Effect of heat and water aging on the durability of rubber-epoxy lining used for rehabilitation of sewer infrastructureIn: Article in journal (Refereed)
    The full text will be freely available from 2019-10-30 16:38
  • 10.
    KHARAZMI, PARASTOU
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Experimental assessment of the state of the lining materials used in the rehabilitation of sewers in residential buildingsIn: Article in journal (Refereed)
    The full text will be freely available from 2019-10-30 16:32
  • 11.
    Kharazmi, Parastou
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Monitoring the quality of sewer renewal using polymeric systems in Sweden2019In: Water practice and technology, E-ISSN 1751-231XArticle in journal (Refereed)
    Abstract [en]

    Water and wastewater pipes require some of the highest levels of infrastructure investment; they also deteriorate faster than they can be repaired. The use of alternative rehabilitation technologies, which are quicker and less expensive than pipe replacement, has therefore increased significantly in recent years, worldwide. Field studies on relined wastewater pipes removed from buildings in different parts of Sweden revealed the existence of a variety of common defects, most of which could have been prevented by better installation. Increased quality-focused monitoring could help to ensure that relined pipes reach their expected service life, while comprehensive documentation could assist in providing sufficient information to facilitate progress in the field. This paper includes a brief overview of the technologies used in Sweden, current quality control practices, repeated observed defects related to installation, crucial steps that affect final quality, and recommendations to be considered in the contexts of detailed quality control and quality assurance procedures.

  • 12.
    Lei, Lei
    et al.
    Gui Lin Univ Elect Technol, Sch Architecture & Transportat Engn, 1 Jinji Rd, Guilin 541004, Peoples R China..
    Chen, Wei
    Gui Lin Univ Elect Technol, Sch Architecture & Transportat Engn, 1 Jinji Rd, Guilin 541004, Peoples R China..
    Xue, Yu
    Dalian Univ Technol, Sch Civil Engn, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    A comprehensive evaluation method for indoor air quality of buildings based on rough sets and a wavelet neural network2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 162, article id UNSP 106296Article in journal (Refereed)
    Abstract [en]

    Understanding the level of indoor air quality is very important to improve the quality of air that people breathe indoors. In this paper, a comprehensive evaluation method combining rough sets and a wavelet neural network is proposed to evaluate the indoor air quality of buildings. Through on-site inspections of the indoor air in six large shopping malls in Beijing, Wuhan and Guangzhou, raw data of the environmental parameters affecting the indoor air quality of large shopping malls are obtained. First, rough sets are used to reduce the dimension of features that affect indoor air quality by removing unimportant features, and important environmental parameters that affect indoor air quality are obtained. These important environmental parameters are used as input parameters of the wavelet neural network. Then, the structure of the wavelet neural network is determined, and an evaluation model of the indoor air quality of buildings based on rough sets and the wavelet neural network is established. Finally, the model is applied to the evaluation of indoor air quality in large shopping malls, and the back propagation neural network, fuzzy neural network and Elman neural network are introduced for comparison of the testing accuracy of the wavelet neural network in the sample testing stage. The results show that the structure of the wavelet neural network is optimized by using a rough set to reduce the redundant attributes of the data, and that the comprehensive evaluation method based on rough sets and a wavelet neural network can accurately evaluate the indoor air quality level of buildings. The results of this study have significance for and can guide the evaluation of the indoor air quality of buildings.

  • 13.
    Liu, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. School of Civil Engineering, ZJU-UIUC, Zhejiang University, Haining 314400, China.
    You, Ruoyu
    Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, 999077, Hong Kong, China.
    Chen, Chun
    Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China ; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
    Modeling transient particle transport by fast fluid dynamics with the Markov chain method2019In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Fast simulation tools for the prediction of transient particle transport are critical in designing the air distribution indoors to reduce the exposure to indoor particles and associated health risks. This investigation proposed a combined fast fluid dynamics (FFD) and Markov chain model for fast predicting transient particle transport indoors. The solver for FFD-Markov-chain model was programmed in OpenFOAM, an open-source CFD toolbox. This study used two cases from the literature to validate the developed model and found well agreement between the transient particle concentrations predicted by the FFD-Markov-chain model and the experimental data. This investigation further compared the FFD-Markov-chain model with the CFD-Eulerian model and CFD-Lagrangian model in terms of accuracy and efficiency. The accuracy of the FFD-Markov-chain model was similar to that of the other two models. For the two studied cases, the FFD-Markovchain model was 4.7 and 6.8 times faster, respectively, than the CFD-Eulerian model, and it was 137.4 and 53.3 times faster than the CFD-Lagrangian model in predicting the steady-state airflow and transient particle transport. Therefore, the FFD-Markov-chain model is able to greatly reduce the computing cost for predicting transient particle transport in indoor environments.

  • 14.
    Ljung, Sebastian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    CFD simulation of particle matter inside an automotive car and the purification efficiency of cabin air purifier2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis work was to study the airflow patterns and the particle distribution in a generic car cabin in order to evaluate the air quality and find how it can be improved. A 3D CAD model was created using the Solidworks software program and meshed using ICEM CFD software. The ICEM CFD software was used to generate the mesh and ANSYS FLUENT was adapted for the simulation. In total, 12 different cases were simulated by considering different inlet velocities and vent setup. The predicted results were further used to analyze the airflow and particle distribution in the entire car cabin. With higher inlet velocity there were more particles being transported to the rear part of the cabin. In general, the particle concentration was higher in the front of the cabin when they were introduced through the inlets, especially with low inlet velocities. Opening the recirculation vents resulted in a slight reduction of the flow to the rear side and reduced the particle distribution accordingly. When smoke particles were introduced in the rear seats, they mostly stayed in the rear of the cabin, especially with low inlet flow velocities as the air did not mix sufficiently. Overall a higher inlet airflow velocity reduced the number of particles that were trapped on the front and rear seats. However, an increase in the number of particles that were trapped on the ceiling, floor and walls were obtained.

     

  • 15.
    Nourozi, Behrouz
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Sustainable building ventilation solutions with heat recovery from waste heat2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The energy used by building sector accounts for approximately 40% of the total energy usage. In residential buildings, 30-60% of this energy is used for space heating which is mainly wasted by transmission heat losses. A share of 20-30% is lost by the discarded residential wastewater and the rest is devoted to ventilation heat loss.

     

    The main objective of this work was to evaluate the thermal potential of residential wastewater for improving the performance of mechanical ventilation with heat recovery (MVHR) systems during the coldest periods of year. The recovered heat from wastewater was used to preheat the incoming cold outdoor air to the MVHR in order to avoid frost formation on the heat exchanger surface.

     

    Dynamic simulations using TRNSYS were used to evaluate the performance of the suggested air preheating systems as well as the impact of air preheating on the entire system. Temperature control systems were suggested based on the identified frost thresholds in order to optimally use the limited thermal capacity of wastewater and maintain high temperature efficiency of MVHR. Two configurations of air preheating systems with temperature stratified and unstratified tanks were designed and compared. A life cycle cost analysis further investigated the cost effectiveness of the studied systems.

     

    The results obtained by this research work indicated that residential wastewater had the sufficient thermal potential to reduce the defrosting need of MVHR systems (equipped with a plate heat exchanger) in central Swedish cities to 25%. For colder regions in northern Sweden, the defrosting time was decreased by 50%. The temperature control systems could assure MVHR temperature efficiencies of more than 80% for most of the heating season while frosting period was minimized. LCC analysis revealed that wastewater air preheating systems equipped with temperature stratified and unstratified storage tanks could pay off their costs in 17 and 8 years, respectively.

  • 16.
    Nourozi, Behrouz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Härer, Simon
    Wang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Uponor AB.
    Ploskic, Adnan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Bravida AB.
    Life cycle cost analysis of air preheating systems using wastewater and geothermal energy2019In: The REHVA European HVAC Journal, ISSN 1307-3729, Vol. 56, no 1, p. 47-51Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Frosting is a common problem in air handling units in buildings in cold climates. Tacklingthis problem is so far achieved by using considerable amount of energy while during thisprocess, the indoor air quality is compromised. This article presents the Life Cycle Cost(LCC) assessment of a preventive solution for frosting using two renewable heat sources.

  • 17.
    Polak, Joanna
    et al.
    Aalborg Univ, Danish Bldg Res Inst, AC Meyers Vaenge 15, DK-2450 Copenhagen SV, Denmark..
    Afshari, Alireza
    Aalborg Univ, Danish Bldg Res Inst, AC Meyers Vaenge 15, DK-2450 Copenhagen SV, Denmark..
    Sadeghian, Parastoo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Wang, Cong
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Improving the performance of heat valve ventilation system: A study on the provided thermal environment2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 164, article id UNSP 106338Article in journal (Refereed)
    Abstract [en]

    The current study presents and evaluates the performance of two types of supply air terminal devices applied in a heat valve ventilation (HVV) system with regard to the provided thermal environment in a room heated and ventilated by the HVV system. To that end, air temperature and air velocity patterns and local thermal discomfort due to draught were studied both experimentally and numerically. Using numerical simulations, parametric analysis was carried out for investigating the provided indoor thermal environment for a wider range of boundary conditions. The considered parameters included the influence of cold vertical surfaces, supply airflow rate and temperature, and room heating energy demand. The results showed that both of the applied air terminal devices could avoid temperature stratification within the occupied zone. The maximum air temperature difference between 0.1 and 1.8 m above the floor was 2.1 degrees C when using a circular valve placed in the external wall below the window and 2.6 degrees C in the case when the air was supplied through three nozzles located in the wall opposite to the window in the upper part of the room. In general, placing the air terminal device below the window provided more uniform air temperature distribution and contributed to the prevention of downdraught caused by a cold window surface. The outcomes of this study are relevant to selecting and designing ventilation and air heating systems for low-energy buildings.

  • 18. Wei, Y.
    et al.
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Xue, Y.
    Zhai, Z.
    Chen, Q.
    Zhang, T.
    Integrated inverse design of ventilation for an aircraft cabin2019In: E3S Web of Conferences, EDP Sciences , 2019Conference paper (Refereed)
    Abstract [en]

    Cabin ventilation is crucial for maintaining thermal comfort and air quality for passengers and crew. The genetic algorithm, proper orthogonal decomposition (POD), and adjoint method have been proposed to inversely design the cabin ventilation. However, each method has its cons and pros. This paper proposed to integrate the above three methods in cascades. The genetic algorithm was applied first in the first stage to roughly circumscribe the ranges of design parameters. Then POD was applied in the next stage to further narrow the ranges and estimate the optimal parametric sets for each design criterion. The estimated optimal design from POD was supplied to the adjoint method for fine tuning. The air-supply parameters of a five-row aircraft cabin were inversely designed to achieve the minimum absolute value of the predicted mean vote (PMV) and the minimum averaged mean age of air. The results showed that the integrated method was able to improve the design stage by stage. The integrated method has superior advantages to assure the optimal design while minimizing the computing expense.

  • 19.
    Wei, Yun
    et al.
    DUT, Sch Civil Engn, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Xue, Yu
    DUT, Sch Civil Engn, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Zhai, Zhiqiang (John)
    DUT, Sch Civil Engn, 2 Linggong Rd, Dalian 116024, Peoples R China.;Univ Colorado, Civil Environm & Architectural Engn, Boulder, CO 80309 USA..
    Chen, Qingyan (Yan)
    Purdue Univ, Sch Mech Engn, W Lafayette, IN 47907 USA..
    Zhang, Tengfei (Tim)
    DUT, Sch Civil Engn, 2 Linggong Rd, Dalian 116024, Peoples R China.;Tianjin Univ, Sch Environm Sci & Engn, Tianjin Key Lab Indoor Air Environm Qual Control, 92 Weijin Rd, Tianjin 300072, Peoples R China.;DUT, Key Lab Ocean Energy Utilizat & Energy Conservat, Minist Educ, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Inverse design of aircraft cabin ventilation by integrating three methods2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 150, p. 33-43Article in journal (Refereed)
    Abstract [en]

    To create a healthy and comfortable aircraft cabin, air-supply parameters of the cabin ventilation system must be designed appropriately. Several methods, such as the computational fluid dynamics (CFD)-based genetic algorithm, CFD-based adjoint method and CFD-based proper orthogonal decomposition (POD), have been developed in recent years for conducing an inverse design. The target environmental performance is specified first, and then the corresponding air-supply parameters are inversely solved with the use of a particular method. However, each method has its pros and cons in terms of efficiency and accuracy. To expedite the inverse design process, this study proposed to integrate the above three methods. The genetic algorithm was adopted first to circumscribe ranges of the air-supply parameters. Next, POD was applied to further narrow the ranges and estimate the optimal air-supply parameters for each design criterion. Finally, the estimated optimal design from POD was supplied to the adjoint method for fine tuning. The above strategy was applied to a five-row aircraft cabin to determine the air-supply opening sizes, directions and temperatures. Criteria that had been proposed specifically for aircraft cabins were used as design targets. Results show that the proposed integration was able to provide the optimal design for each design target. The integrated optimal design was superior to the design provided by each individual method. The bottleneck in further acceleration of the integrated design was the hundreds of design cases resolved by full CFD simulation.

  • 20.
    Xue, Yu
    et al.
    Dalian Univ Technol, Sch Civil Engn, Dalian 116024, Peoples R China..
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Wang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Uponor AB, Hackstavagen 1, S-72132 Vasteras, Sweden..
    Bu, Fang
    Beijing Aerosp Inst Metrol & Measurement Technol, Beijing 10000, Peoples R China..
    Development of an integrated approach for the inverse design of built environment by a fast fluid dynamics-based generic algorithm2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 160, article id 106205Article in journal (Refereed)
    Abstract [en]

    It is essential to further design built environments with improved thermal comfort level, air quality, and reduced energy consumption of the HVAC system. The CFD-based GA was able to identify the global optimal design, but this method requires numbers of CFD simulations which is time consuming. Besides, there is no general rule in determining the critical parameters of GA, such as population size, mutation rate, and crossover rate. Therefore, this study adopted the FFD instead of CFD and developed the FFD-based GA in OpenFOAM. By testing the FFD-based GA in designing the thermal environment in an office with displacement ventilation, it was found that the FFD-based GA had the similar performance with that of the CFD-based GA and saved more than 75% computational effect. Making use of the efficiency of the FFD-based GA, this investigation tested the effect of population size, mutation rate, and crossover rate on the inverse design by GA. In the same design case, the appropriate population size was and mutation rate was m = 0.1, while the crossover rate had no general effect on the inverse design.

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