An independent industry of Environmental Control Officers (ECOs) is active on various construction sites across South Africa. It forms part of a global network of verifiers, such as Environmental Impact Assessment (EIA) and EIA follow-up verifiers. This network authenticates statements about and the implementation of sustainability commitments made during the planning phase of major construction projects. International studies show that the construction industry is experiencing many challenges to deliver sustainability commitments, including inadequate collaboration between role players, illdefined roles and responsibilities, and insufficient use of environmental governance approaches. On-site verifiers like ECOs may aid in restraining these challenges by bridging ineffective governance approaches, such as classic EIA with new governance approaches, for instance self-responsibility (e.g. Environmental Management Systems (EMSs)) and involvement of third parties. Moreover, an “independent from all” verification function may be vital in developing countries such as South Africa, where trust between the government, market and public is particularly fragile due to historical injustices. Interestingly, limited learning has been drawn and shared from this function’s real-world experience. There are also differing views on the role, independence and value of ECOs, due to roles, frequent interaction with persons responsible for delivering sustainability commitments, and collaboration with third parties being ill-defined. The overarching purpose of this study is to advance understanding of independent ECOs in major South African construction projects. Three lines of inquiry are followed. The first is to define what the role is, or ideally should be, of an ECO in the South African compliance monitoring and enforcement effort. The second is to identify what factors might influence the independence of verifiers. The third is to appraise how and to what extent independent EIA follow-up verifiers add value in major construction projects in the developing country context of South Africa. This study’s research assumptions are based on the real world of ECOs and uses a mixed method research approach to draw knowledge from the industry. The strategies of inquiry include a survey, interviews, and multiple case study evaluations. The methods for data collection include literature review, a self-administered survey questionnaire, semi-structured interviews, video material, observations of practice at case studies, and the collection of project documentation. The methods used for data analysis are the categorisation and measuring of opinions and statements of survey participants, the analysis of video material and project documentation, and the nominal categorisation and ordinal scaling of case study results. Three journal articles capture the essence of the research results and form part of the thesis report, as prescribed by the North-West University’s rules for doctoral theses in article format. All three articles were peer-reviewed and published in journals aimed at international audiences. Article 1 of the thesis highlights that an industry of ECOs fulfils numerous roles at various construction sites across South Africa. The results identify the importance of ECOs functioning independently of all role-players, but warn that obsessing about independence may compromise the ability of ECOs to fulfil their roles. The results also show that industry is in need of competence and the regulation thereof, as well as support from all role players. By drawing from the research results, the thesis defines an ECO. Article 2 of the thesis reiterates that independence is central to internationally acclaimed verification fields and important to ensure the credibility of EIA. The study identifies 18 factors that might influence the independence of EIA follow-up verifiers and divides the factors into five categories: financial, commercial, professional, personal, and other. By identifying and sharing these factors, this thesis aids in anticipating and avoiding potential conflict of interest between environmental role players. Article 3 strengthens the continuum between environmental governance approaches by conceptualising a framework for appraising the value of independent EIA follow-up verifiers. The framework provides for inter-linking principles and objectives of sustainability to the performance areas of EIA, EIA follow-up and the EMS. The appraisal results indicate that independent verifiers add most value when they are involved in screening, checking compliance, influencing decisions, community engagement, and integrating environmental governance approaches. The study confirms the benefits of adaptable, proactive, experienced, and independent EIA follow-up verifiers, such as ECOs, on major South African construction projects. / PhD (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2015

O grapsídeo Pachygrapsus transversus apresenta uma estratégia reprodutiva alternativa entre os braquiúros. A espécie atinge a maturidade sexual muito cedo, poucos meses após recrutar no entre-marés, e as fêmeas podem sofrer uma muda, após o principal período de reprodução, para um estágio no qual a morfologia do abdômen e seus apêndices difere claramente tanto da característica adulta como da juvenil. Nessa condição não ocorre atividade reprodutiva. Devido ao fato dessa dinâmica responder a um ciclo sazonal, foi testado o efeito da temperatura, do fotoperíodo e da interação de ambos na incidência da muda da puberdade, na manutenção da atividade reprodutiva e na muda para o estágio de inatividade. Para tal, foram mantidos lotes de animais em cativeiro em quatro diferentes combinações de fotoperíodo e temperatura durante dois períodos. Os resultados do primeiro período demonstram que o crescimento, a alometria abdominal e a proporção de indivíduos que realizaram a muda da puberdade foram mais elevados em condições de temperatura condizentes ao inverno. No segundo período, fêmeas adultas apresentaram crescimento superior sob condições de fotoperíodo e temperatura de inverno, enquanto que a proporção de fêmeas em repouso sexual foi elevada, porém indistinta, em todas as condições experimentais. Não foram verificadas diferenças de crescimento entre fêmeas em atividade sexual e indivíduos em repouso reprodutivo. Posteriormente, foi realizado um experimento para analisar a dinâmica da alteração morfotípica na presença de conspecíficos (fêmea sozinha, fêmea na presença de macho e fêmea na presença de outra fêmea) em diferentes níveis de interação (química, visual, táctil). Nesse experimento não foi registrada regressão abdominal para nenhuma das fêmeas, não havendo quaisquer diferenças entre crescimento e alometria abdominal entre os tratamentos. Por fim, foi analisado o comportamento de machos frente a fêmeas de diferentes morfótipos. Os resultados demonstraram que machos conseguem discriminar fêmeas em repouso daquelas aptas à reprodução, passando mais tempo em atividades de contato físico, incluindo cópula, com as últimas. Os resultados obtidos mostram que o crescimento é influenciado por variáveis físicas (temperatura e fotoperíodo), e que a manutenção da atividade reprodutiva, limitada pela ocorrência de mudas para estágios de repouso reprodutivo, parece estar relacionada à presença de conspecíficos. Essa estratégia permitiria uma segregação temporal eficiente de atividades de reprodução e crescimento (em longo prazo), crucial para esta espécie que apresenta maturidade sexual precoce. / The grapsid crab Pachygrapsus transversus undergoes an alternative reproductive strategy compared to other brachyurans. This species reaches maturity early in its ontogeny, few months after recruiting to the rocky intertidal. After the main breeding period, females may molt to a stage, marked by a regression of the abdomen and its appendages, which are easily distinguished from both the juvenile and adult form. In this condition, there is no reproductive activity. Because the frequency of different adult morphotypes changes in a seasonal basis, the effect of temperature, photoperiod and their interaction on the incidence of the puberty molt (for juveniles), the maintenance of reproductive activity and the proportion of females molting to a resting stage (adults) was tested. With this purpose, different female groups were kept in captivity under four different combinations of photoperiod and temperature, during two experimental trials. The results of the first experiment show that growth, abdominal allometry and the proportion of females molting to maturity were all higher under winter temperature. In the second experiment, adult females exhibited higher growth rate under winter conditions of photoperiod and temperature, while the proportion of females molting to a resting stage was generally high, with no significant differences among treatments. Growth did not differ between females exhibiting abdominal regression and females holding the adult breeding condition. A third experiment was conducted to examine the dynamics of morphotypic shift under the presence of conspecifics (isolated females, females held with another female, and females held with a male) in different interaction levels (chemical, visual, tactile). In this experiment, no females undergone abdominal regression, and no differences were observed in growth rate and abdominal allometry among treatments. In a final experiment, the behavioral response of males facing resting and active females was compared. Results demonstrated that males can discriminate these morphotypes. Physical contact, including copula, took longer when males were confronted with the reproductive morphotype. It is concluded that growth is mostly influenced by physical variables (temperature and photoperiod), while holding or not reproductive activity, dictated by the incidence of females molting to a resting stage, is apparently related to the presence of conspecifics. This strategy would allow an efficient temporal segregation between reproduction and growth (in the long run), which might be crucial for a species undergoing precocious sexual maturity.

This thesis documents the modelling of generic Environmental Control System(ECS) of an aircraft in Modelica by utilizing components from free version of theTTECCS (Technical Thermodynamic Environmental Control and Cooling Systems) library. In doing so, components used for developing ECS from the TTECCS library are mathematically verified with theoretical formula in MATLAB. Selected components are investigated with valid input data to initialize the simulation and verify its behaviors with corresponding available data. Hereinafter, the object-oriented modelling method is used to integrate ECS components to develop a functional system. The main function of ECS is to regulate the pressure and temperature inside the cabin to accepted physiology flight safetylevels. Different types of ECS architecture are presented in this document. An ECS developed here is based on the bootstrap system and consists only one cooling unit comprised with the source, pipes, two heat exchanger, compressor, turbine, temper-ature control valve, pressure control valve, and sinks. Dry air(Ideal gas) is used as a medium in the system. Temperature drop along each component corresponds to available A320 cruise flight data in order to calculate the top level parameter and to initialize the components, subsequently an ECS system. Several systematized methods for Object-oriented modelling and system design were studied and steps are extracted accordingly that suits to initiate the procedurefor this project, which is also presented. Time domain simulation is performed inModelica and Dymola. A simplified control system is built to regulate the system, therefore restrained it as a future work to develop real in-flight condition control system of an ECS.Top level parameters were selected within valid customized ranges for developing a performance map of the components. After generating the map, optimal data from the map were taken to initialize final ECS. The simulation results of the final model is then compared to A320 flight data which is comparable in behavior; this was expected. Above all, simulation environment Modelica and free version of TTECCS library components are reliable to develop ECS in order to investigate ECS components behavior and predict cabin conditions before developing a prototype.

The cabin environment of a commercial aircraft, including cabin layout and the quality of air supply, is crucial to the airline operators. These aspects directly affect the passengers’ experience and willing to travel. This aim of this thesis is to design the cabin layout for flying wing aircraft as part of cabin environment work, followed by the air quality work, which is to understand what effect the ECS can have in terms of cabin air contamination. The project, initially, focuses on the cabin layout, including passenger cabin configuration, seat arrangement and its own size due to the top requirements, of a conventional aircraft and further into that of a flying wing aircraft. The cabin work in respect of aircraft conceptual design is discussed and conducted by comparing different design approaches. Before the evaluation of cabin air quality, an overall examination of the main ECS components involved in the contaminants access will be carried on and, therefore, attempt to discover how these components influence the property of the concerned contaminants. By case study in the B767 ECS, there are some comments and discussions regarding the relationship between the cabin air contaminations and the passing by ambient environment. The thesis ends up with a conclusion explaining whether or not the contaminated air enters the occupants’ compartments on aircraft and proposing some approaches and engineering solutions to the continue research.

Nowadays the aviation industry is playing an important role in our daily life, since is the main medium that satisfies the present human needs to reach long distances in the fastest way. But such benefit doesn’t come free of collateral consequences. It is estimated that each year, only the air transport industry produces 628 mega tonnes of CO2. Therefore, urgently actions need to be implemented considering that the current commercial fleet will be doubled by 2050. The research field for more efficient aircraft systems is a very constructive field; where novel ideas can be exploited towards the mitigation of the coming air transport development. In this research the configuration of the Environmental Control System (ECS) has been analysed aiming to reduce its energy consumption for both, fixed-wing and rotary-wing aircraft. This goal is expected to be achieved mainly through the replacement of the main source of power that supplies the ECS, from pneumatic to electric. Differently from the conventional ECS, a new electric-source technology is integrated in the system configuration to compare its effects on the energy consumption. This new technology doesn’t bleed air directly from the engines; instead of that, it takes the air directly from the atmosphere through the implementation of an electric compressor. This new technology has been implemented by Boeing in one of its most recent airplanes, the B787. Towards achieving the main goal, a framework integrated with five steps has been designed. An algorithmic analysis is integrated on the framework. The first step meets the required aircraft characteristics for the analysis. The second step is in charge of meeting the mission profile characteristics where the overall analysis will be carried out. The third step assesses the conventional ECS penalties. The fourth step carries out a complex analysis for the proposed electric ECS model, from its design up to its penalties assessment. The fifth step compares the analysis results for both, the conventional and the electric models. The fourth step of the framework, which analyses the electric ECS, is considered the most critic one; therefore is divided in three main tasks. Firstly, a small parametric study is done to select an optimum configuration. This task is carried out towards meeting the ECS air conditioning requirements of a selected aircraft. Secondly, the cabin temperature and pressurization are simulated to analyse the response of the configured electric ECS for a mission profile. And finally, the fuel penalties are assessed in terms of system weight, drag and fuel due power-off take. To achieve the framework results, a model which receives the name ELENA has been created using the tool Simulink®. This model contains 5 interconnected modules; each one reads a series of inputs to perform calculations and exchange information with other modules.

Echinococcus granulosus is a cestode species responsible for human cystic echinococcosis (CE). The domestic dog is the primary definitive host for the transmission of E. granulosus infection to domestic livestock intermediate hosts and to humans. In order to determine the prevalence and risk factors for canine echinococcosis, epidemiological studies were conducted in known endemic localities in three different countries i.e. Libya, Kenya and Wales. Stray dogs were subject to direct examination of the small intestine at necropsy. Owned dogs (total n=1659) were screened for E. granulosus infection using a genus specific coproantigen ELISA test that was restandardised against 75 dog necropsy results, and exhibited 100% sensitivity and 98% specificity. Analysis of risk factors for canine echinococcosis associated with Echinococcus coproantigen positive results was evaluated based on dog-owner questionnaires. In Libya, the overall infection of E. granulosus in autopsied dogs was 25.8%, and an overall coproantigen prevalence of 21.6% was obtained for owned dogs (n= 334). Risk factors (p<0.05) for a coproantigen positive owned dog in Libya were, dog age (≤5 years), non-restraint of dogs, dogs fed on offal, sheepdog class, owners that did not de-worm their dogs, and dogs owned by farmers who admitted to frequent slaughter of livestock. Dog sex was not a significant risk factor for a positive coproantigen ELISA in dogs from all study areas. Worm burdens in necropsied dogs in Libya ranged from 29 to 2900 (mean 1064) and were positively correlated to coproantigen ELISA OD values (r= 0.76), but negatively associated with dog age (r= -0.64). Canine echinococcosis in Libya measured by locality varied, with Alkhums (Leptis-Magna) district having the highest coproantigen prevalence at 38.7% (p=0.001), followed by Azahwia district with 19.2%. Tripoli district had the lowest coproprevalence where 17.5% of dogs were copro-positive. In Tripoli an abattoir survey for livestock CE was also undertaken and is reported. In northern Kenya, post-mortem examination of the small intestines of 17 dogs from Turkana, revealed 29.4% harboured E. granulosus infection, with a mean worm burden of 1570 adults. Overall 26% (42/161) of Turkana dogs were copro-positive, with the highest copro-prevalence identified in dogs from Lokichoggio division. Younger dogs (≤5 years), free-roaming dogs, dogs fed on offal, and dogs of owners that practiced home slaughter of livestock and that had no knowledge about echinococcosis, appeared to have a significantly higher risk of being coproantigen positive (p<0.05). In mid-Wales a list of 321 sheep farms were selected at random, from which 1164 farm-dogs were screened using rectal faecal samples tested for Echinococcus coproantigens, and owners questioned using a modified dog-owner questionnaire. Furthermore, the potential impact of the 2001 footand- mouth disease (FMD) epidemic, on the prevalence of E. granulosus in farm dogs was assessed. An overall coproantigen positive rate of 8.0% was recorded on 22% of farms surveyed, which compared to a rate of 3.4% obtained in the same region in 1993. There was no significant difference in copro-positive prevalence between FMD affected properties and those that were unaffected. Significant risk factors for a positive farm dog in Wales were associated with allowing dogs to roam free, and infrequent deworming (>4month intervals) of dogs. The data are discussed in relation to a previous pilot hydatid control program in that area of Wales (1983-89) and the potential for increase in transmission to humans. Identification of risk factors associated with canine echinococcosis appear to be similar in all three communities studied and help to demonstrate practices that may be amenable to change as part of hydatid control programmes.

O grapsídeo Pachygrapsus transversus apresenta uma estratégia reprodutiva alternativa entre os braquiúros. A espécie atinge a maturidade sexual muito cedo, poucos meses após recrutar no entre-marés, e as fêmeas podem sofrer uma muda, após o principal período de reprodução, para um estágio no qual a morfologia do abdômen e seus apêndices difere claramente tanto da característica adulta como da juvenil. Nessa condição não ocorre atividade reprodutiva. Devido ao fato dessa dinâmica responder a um ciclo sazonal, foi testado o efeito da temperatura, do fotoperíodo e da interação de ambos na incidência da muda da puberdade, na manutenção da atividade reprodutiva e na muda para o estágio de inatividade. Para tal, foram mantidos lotes de animais em cativeiro em quatro diferentes combinações de fotoperíodo e temperatura durante dois períodos. Os resultados do primeiro período demonstram que o crescimento, a alometria abdominal e a proporção de indivíduos que realizaram a muda da puberdade foram mais elevados em condições de temperatura condizentes ao inverno. No segundo período, fêmeas adultas apresentaram crescimento superior sob condições de fotoperíodo e temperatura de inverno, enquanto que a proporção de fêmeas em repouso sexual foi elevada, porém indistinta, em todas as condições experimentais. Não foram verificadas diferenças de crescimento entre fêmeas em atividade sexual e indivíduos em repouso reprodutivo. Posteriormente, foi realizado um experimento para analisar a dinâmica da alteração morfotípica na presença de conspecíficos (fêmea sozinha, fêmea na presença de macho e fêmea na presença de outra fêmea) em diferentes níveis de interação (química, visual, táctil). Nesse experimento não foi registrada regressão abdominal para nenhuma das fêmeas, não havendo quaisquer diferenças entre crescimento e alometria abdominal entre os tratamentos. Por fim, foi analisado o comportamento de machos frente a fêmeas de diferentes morfótipos. Os resultados demonstraram que machos conseguem discriminar fêmeas em repouso daquelas aptas à reprodução, passando mais tempo em atividades de contato físico, incluindo cópula, com as últimas. Os resultados obtidos mostram que o crescimento é influenciado por variáveis físicas (temperatura e fotoperíodo), e que a manutenção da atividade reprodutiva, limitada pela ocorrência de mudas para estágios de repouso reprodutivo, parece estar relacionada à presença de conspecíficos. Essa estratégia permitiria uma segregação temporal eficiente de atividades de reprodução e crescimento (em longo prazo), crucial para esta espécie que apresenta maturidade sexual precoce. / The grapsid crab Pachygrapsus transversus undergoes an alternative reproductive strategy compared to other brachyurans. This species reaches maturity early in its ontogeny, few months after recruiting to the rocky intertidal. After the main breeding period, females may molt to a stage, marked by a regression of the abdomen and its appendages, which are easily distinguished from both the juvenile and adult form. In this condition, there is no reproductive activity. Because the frequency of different adult morphotypes changes in a seasonal basis, the effect of temperature, photoperiod and their interaction on the incidence of the puberty molt (for juveniles), the maintenance of reproductive activity and the proportion of females molting to a resting stage (adults) was tested. With this purpose, different female groups were kept in captivity under four different combinations of photoperiod and temperature, during two experimental trials. The results of the first experiment show that growth, abdominal allometry and the proportion of females molting to maturity were all higher under winter temperature. In the second experiment, adult females exhibited higher growth rate under winter conditions of photoperiod and temperature, while the proportion of females molting to a resting stage was generally high, with no significant differences among treatments. Growth did not differ between females exhibiting abdominal regression and females holding the adult breeding condition. A third experiment was conducted to examine the dynamics of morphotypic shift under the presence of conspecifics (isolated females, females held with another female, and females held with a male) in different interaction levels (chemical, visual, tactile). In this experiment, no females undergone abdominal regression, and no differences were observed in growth rate and abdominal allometry among treatments. In a final experiment, the behavioral response of males facing resting and active females was compared. Results demonstrated that males can discriminate these morphotypes. Physical contact, including copula, took longer when males were confronted with the reproductive morphotype. It is concluded that growth is mostly influenced by physical variables (temperature and photoperiod), while holding or not reproductive activity, dictated by the incidence of females molting to a resting stage, is apparently related to the presence of conspecifics. This strategy would allow an efficient temporal segregation between reproduction and growth (in the long run), which might be crucial for a species undergoing precocious sexual maturity.

Spacecraft thermal protection systems are at risk of being damaged due to airflow produced from Environmental Control Systems. There are inherent uncertainties and errors associated with using Computational Fluid Dynamics to predict the airflow field around a spacecraft from the Environmental Control System. This paper describes an approach to quantify the uncertainty in using Computational Fluid Dynamics to predict airflow speeds around an encapsulated spacecraft without the use of test data. Quantifying the uncertainty in analytical predictions is imperative to the success of any simulation-based product. The method could provide an alternative to traditional “validation by test only” mentality. This method could be extended to other disciplines and has potential to provide uncertainty for any numerical simulation, thus lowering the cost of performing these verifications while increasing the confidence in those predictions. Spacecraft requirements can include a maximum airflow speed to protect delicate instruments during ground processing. Computational Fluid Dynamics can be used to verify these requirements; however, the model must be validated by test data. This research includes the following three objectives and methods. Objective one is develop, model, and perform a Computational Fluid Dynamics analysis of three (3) generic, non-proprietary, environmental control systems and spacecraft configurations. Several commercially available and open source solvers have the capability to model the turbulent, highly three-dimensional, incompressible flow regime. The proposed method uses FLUENT, STARCCM+, and OPENFOAM. Objective two is to perform an uncertainty analysis of the Computational Fluid Dynamics model using the iv methodology found in “Comprehensive Approach to Verification and Validation of Computational Fluid Dynamics Simulations”. This method requires three separate grids and solutions, which quantify the error bars around Computational Fluid Dynamics predictions. The method accounts for all uncertainty terms from both numerical and input variables. Objective three is to compile a table of uncertainty parameters that could be used to estimate the error in a Computational Fluid Dynamics model of the Environmental Control System /spacecraft system. Previous studies have looked at the uncertainty in a Computational Fluid Dynamics model for a single output variable at a single point, for example the re-attachment length of a backward facing step. For the flow regime being analyzed (turbulent, three-dimensional, incompressible), the error at a single point can propagate into the solution both via flow physics and numerical methods. Calculating the uncertainty in using Computational Fluid Dynamics to accurately predict airflow speeds around encapsulated spacecraft in is imperative to the success of future missions

The protection regime for products of human activity is a critical component of modern environmental and public health policy. This paper provides a broad overview of the general considerations surrounding the regime for pollutants and products, which aim to protect both human and environmental well-being. This paper gives a historical overview of the evolution of environmental policies concerning the management of waste and chemical substances. It discusses the growing recognition of the potential risks posed by various human-made substances and products, enumerating the provisions related to the regime of harmful products and substances This article underlines the need for a robust regulatory framework to address these concerns, outlining the primary objectives of the substances and products regime, including the protection of human health, the preservation of the environment and the promotion of sustainable production and consumption. It examines the key components of the regime, such as the identification and classification of harmful substances, the establishment of safety standards and exposure limits, and the implementation of control measures and enforcement mechanisms, by exploring the complexities and challenges associated with the effective implementation of the toxic substances and products regime, including scientific uncertainties, stakeholder interests and the need for international cooperation. In conclusions we summarize the key findings and highlight the importance of continued research, policy development and collaborative efforts to further strengthen the protection regime for products of human activity. This article provides a concise yet comprehensive overview of the key aspects covered and sets the stage for a detailed examination of the pollutant and product regime and its impact on the environment and public health.

The present thesis deals with the analysis of Environmental Control System (ECS) as a part of the aircraft conceptual design. The research focuses on developing methods for modelling, simulation and optimization of current and future cooling technologies suitable for aircraft applications. The work started with a pre-study in order to establish the suitability of different cooling technologies for ECS application. Therefore, five technologies namely, Bootstrap (BS), Reverse-Bootstrap (RBS), vapour cycle system (VCS), magnetic cooling (MC) and thermo-electric cooling (EC), were assessed from a theoretical point of view by the method of benchmarking. This resulted into the selection of three most suitable technologies that were further modelled and simulated in Dymola. In order to compare the optimum designs for each technology, the models were optimized using the modeFRONTIER software. The comparison was performed based on the optimum ratio of maximum power of cooling and minimum fuel penalty. The results showed that VCS has the “best” performances compared to BS and RBS. In addition to the active technologies, passive cooling methods such as liquid cooling by means of jet-fuel and poly-alpha-olefin were considered to address high heat transfer rates. In order to apply the cooling technologies in the ECS, concept system architectures were formulated using the functional analysis. This led to the identification of basic functions, components and sub-systems interaction. Based on the comparison carried out previously and the functional analysis, two ECS architectures were developed. Design optimization procedure was applied further in order to assess each concept and also to study the differences between the two concept architectures. The results depict the complex interaction of different key parameters of the architectures and their influence on the outcome. The study culminated with a proposed methodology for formulation of systems architecture using information from the optimization results and a robust functional analysis method. To sum up, the thesis proposes a simulation-based optimization method that allows inclusion of ECS system in aircraft conceptual design phase. The study also proves the complexity of the conceptual design stage for ECS architectures which highly influences the design of the combat aircraft.