Les performances de filtration des filtres de CTA vis-à-vis de particules et d’aérosols microbiens (AM) ont été étudiées ainsi quel’influence des conditions opératoires sur le comportement de microorganismes collectés sur les filtres. A l’échelle du laboratoire, une mini CTA ayant deux étages de filtration en série a été développée et validée pour l’étude de filtres prototypes ayant des géométries industrielles. Trois types de filtres de différentes efficacités ont été considérés : G4, F7 et F9 selon la norme EN 779. Deux configurations de filtres ont été étudiées : 1) G4 plan plissé/F7 à poches et 2) F7/F9 à poches. Les filtres ont été colmatés séquentiellement par des particules d’alumine, qui assurent une fraction minérale, puis du riz microniséqui apporte le champignon Penicillium chrysogenum et assure une fraction organique agissant comme substrat pour les microorganismes. Enfin, un AM composé d’endospores de Bacillus subtilis et de spores d’Aspergillus niger a été nébulisé pour la contamination des filtres. Après colmatage, des périodes de marche/arrêt de la ventilation de différentes durées (10 j ou 6 semaines) ont été simulées. Lors des reprises de la ventilation, des comptages de particules et d’AM en avaldes filtres ont été effectués. Les principaux résultats sont : (i) les filtres placés en 2ème étage présentent un colmatage plus faible que ceux du 1er étage de filtration, (ii) survie de B. subtilis, croissance de P. chrysogenum et décroissance d’A. niger sur les filtres quelle que soit la période d’arrêt de ventilation étudiée, et (iii) lors des reprises de ventilation, il n’a pas été observé de relargage d’AM pour la fraction échantillonnée.D’autre part, deux CTA à pleine échelle ont été étudiées pendant 6 mois. Une CTA ayant deux étages de filtration avec une configuration G4 plan plissé/F7 à poches, traite l’air extérieur et le souffle vers des locaux desservis. L’autre CTA correspond à l’extraction de l’air vicié d’un local pour le rejeter vers l’extérieur. La perte de charge des filtres, l’humidité relative, et la température de l’air ont été suivies en continu. L’efficacité des filtres vis-à-vis des particules et des aérosols microbiens a été mesurée une fois par mois. Une méthodologie originale de suivi mensuel de la concentration des microorganismescollectés sur les filtres a été mise en oeuvre. Les principaux résultats sont : (i) faible évolution de la perte de charge du filtre placé en 2ème étage, (ii) efficacité des filtres G4 comparable à celle des filtres G4 prototypes, (iii) efficacité du filtre F7 plus faible que celle des filtres prototypes, ce qui peut être expliqué par une différence de vitesse de filtration entre les deux échelles, (iv) le filtre G4 de la CTA-extraction contient une concentration de microorganismes 10 fois plus élevée que celle du filtre G4 de la CTA-soufflage après 6 mois de fonctionnement. / Filtration performances of Air Handling Units (AHU) filters regarding particles and microbial aerosols have been studied, as well as the influence of the AHU operational conditions on behavior of microorganisms collected on the filters. A lab-scale AHU with two successive filtration stages was developed and validated for the study of prototype filters with industrial geometries. Three types of filters of different efficiency have been considered : G4, F7 and F9 according to EN 779 Standard. Two configurations of filters were considered: 1) G4 pleated/F7 bag and 2) F7/F9 bag. Filters were sequentially clogged by alumina particles which assured a mineral fraction, and then by micronized rice particles which provides the fungi Penicillium chrysogenum and assures an organic fraction which acts as a substrate for microorganisms. Finally, a microbial aerosol composed by endospores of Bacillus subtilis and spores of Aspergillus niger was nebulized for filters contamination. After clogging, stops and restarts of ventilation were simulated for different durations (10 days or 6 weeks). During restarts of ventilation, particles and microbial aerosols samplings were performed downstream of the filters. Main results are: (i) level of clogging is significantly less important for the 2nd filtration stage than for the first one, (ii) survival of B. Subtilis, growth of P. Chrysogenum and decline of A.niger on the filters whatever the period of time studied, and (iii) during restarts of ventilation, microbial aerosols releasing was not detected for sampled fraction. Moreover, two full-scale AHU were studied during 6 months. One of the AHU studied is equipped with two filters in series: a G4 pleated filter in 1st stage and a F7 bag filter in 2nd stage. This AHU treats the outdoor air to blow it towards the indoor environments. The other one extracts the indoor air to reject it back outdoors. The filters pressure drop, relative humidity and temperature of the air were measured continuously. Filters efficiency regarding particles and microbial aerosols were measured once a month. An original methodology for the monthly estimation of the concentration of microorganisms on the filters was implemented. Main results are: (i) no significant evolution of the filter pressure drop in 2nd stage, (ii) efficiency of G4 filters are comparable to the prototype filtersone, (iii) efficiency of F7 filters are lower than prototype filters one, which can be explained by differences of filtration velocity between the two scales, (iv) after 6 months of operation, concentration of microorganisms on G4 filter of the AHU of extraction is 10 times higher than the G4 filter one of AHU who treats outdoor air.

As the popularity of building automation system (BAS) increases, there is an increasing need to understand/analyze the HVAC system behavior with the monitoring data. However, the current constraints prevent FDD technology from being widely accepted, which include: 1)Difficult to understand the diagnostic results; 2)FDD methods have strong system dependency and low adaptability; 3)The performance of FDD methods is still not satisfactory; 4)Lack of information. This thesis aims at removing the constraints, with a specific focus on air handling unit (AHU), which is one of the most common HVAC components in commercial buildings. To achieve the target, following work has been done in the thesis. On understanding the diagnostic results, a standard information structure including probability, criticality and risk is proposed. On improving method's adaptability, a low system dependency FDD method: rule augmented CUSUM method is developed and tested, another highly adaptable method: principal component analysis (PCA) method is implemented and tested. On improving the overall FDD performance (detection sensitivity and diagnostic accuracy), a hypothesis that using integrated approach to combine different FDD methods could improve the FDD performance is proposed, both deterministic and probabilistic integration approaches are implemented to verify this hypothesis. On understanding the value of information, the FDD results for a testing system under different information availability scenarios are compared. The results show that rule augmented CUSUM method is able to detect the abrupt faults and most incipient faults, therefore is a reliable method to use. The results also show that overall improvement of FDD method is possible using Bayesian integration approach, given accurate parameters (sensitivity and specificity), but not guaranteed with deterministic integration approach, although which is simpler to use. The study of information availability reveals that most of the faults can be detected in low and medium information availability scenario, moving further to high information availability scenario only slightly improves the diagnostic performance. The key message from this thesis to the community is that: using Bayesian approach to integrate high adaptable FDD methods and delivering the results in a probability context is an optimal solution to remove the current constraints and push FDD technology to a new position.

Fault in Air Handling Unit (AHU) of the Heating, Ventilation, and Air Conditioning (HVAC) systems in buildings is a challenge that building managements face. These faults cause buildings to waste 15 – 30% of the energy consumed by the AHU. This thesis aims to study the causes of faults in the AHU and proposes a machine learning model that could be used to detect these faults. These faults could either be failure of AHU equipment, failure of the actuator, or failure of sensor and feedback controller. To achieve this, the data driven method of fault detection was applied. Collected data was preprocessed by removing missing values, eliminating correlated features, nominal features were one-hot encoded, and class imbalance was managed by over-sampling and under-sampling techniques. Finally, Principal Component Analysis (PCA) technique was applied to the over-sampled dataset. Both over-sampled and under- sampled datasets were split by 70/30 ratio for train and test sets, respectively. Classification models were built using Random Forest, Decision Tree and Support Vector Machines for both binary and multiclass classifications. GridSearchCV cross validation technique was used to train the models and the optimal parameters for each model selected. Results from multiclass classifications, show that Random Forest performed best with over sampling and PCA having 100% on accuracy, 100% on precision, 100% on recall, and 100% on f1 score while with under-sampling without PCA, Support Vector Machines performed best with 91% on accuracy, 91% on precision, 91% on recall, and 90% on f1 score. This illustrates that machine learning could be used to detect faults in AHU with accuracy above 90%. Analyzing the results, the proposed machine learning models could detect the most important failure causes and the predictors of faults in AHU.

Dissertation (M.Appl.Sc.) -- Lincoln University, 2007. / Includes bibliographical references.

Thesis (Ph. D.) -- Lincoln University, 2008. / Also available via the World Wide Web.

Energieffektiviseringar behövs för att klara klimatmålen. Syftet med detta arbete har därför varit att undersöka ventilationen i förskolebyggnaden Rymden i Eskilstuna kommun. Fokus i arbetet har legat på att göra en analys på energibesparingar där variabelt luftflöde, VAV-system och konstant luftflöde, CAV-system jämförs i tre olika scenarier. Metodiken för att lösa arbetets frågeställningar har varit genom informationsinsamling, beräkningsprogram, intervju samt platsbesök. Informationsinsamling har varit i form av vetenskapliga tidskrifter samt arbeten som behandlar det aktuella problemområdet. Olika programvaror har använts, dessa är MagiCAD, IDA ICE, Sektionsdata 4.21 samt Microsoft Excel. För ökad förståelse för den aktuella byggnaden har platsbesök gjorts på förskolebyggnaden samt en intervju med den projektöransvarige för ventilationen i förskolan. Resultatet visar att den mest energieffektiva systemlösningen är en roterande värmeväxlare med VAV-styrning i kombination med en korsströmsvärmeväxlare för köksavdelningen. VAV-styrning med en sådan systemlösning har en total årlig energianvändning på 20 684 kWh, medan CAV-systemet med samma systemlösning använder 30 900 kWh. Ekonomisk analys visar däremot att CAV-systemet med samma systemlösning är mest lönsam. Den totala livscykelkostnaden, LCC ligger på 2 386 857 kr för CAV-systemet vid en kalkyltid på 30 år, i jämförelse med 2 420 117 kr för VAV-systemet. För att VAV-systemet skall vara lönsam, visar känslighetsanalysen att kalkylräntan måste sjunka från 5 % till 2,56 % eller energiprisutvecklingen öka med 2,44 % årligen eller en sänkning av den årliga underhållskostnaden för VAV-styrning med 2 164 kr. Övrig känslighetsanalys visar att vid nederbörd då personer stannar inomhus är det fördel för VAV-systemet, då skillnaden i total LCC-kostnad sjunker med 1 758 kr. Vid 74 % av personnärvaro minskar LCC-skillnaden mellan systemen från 39 240 kr till 26 371 kr, alltså utgör detta även en fördel för VAV-systemet. Slutsatsen som dras för förskolebyggnaden Framtiden är att större energibesparingar kan göras med ett VAV-system, men ett CAV-system är bättre ur en ekonomisk synpunkt. Känslighetsanalysen visar dock att små förändringar behövs för att VAV-systemet skall bli ekonomiskt lönsamt. Andra faktorer som påverkar valet mellan VAV- och CAV-system är exempelvis en minskning av personnärvaron relativt till det dimensionerade. En sådan minskning utgör en fördel för VAV-systemet. Detta på grund av att med ett CAV-system överventileras byggnaden. Även högre specifik fläkteffekt har en stor betydelse i valet, då mer energiåtgång till fläktarna leder till större energibesparing för VAV-system. En högre temperaturverkningsgrad för luftbehandlingsaggregat medför däremot en fördel för CAV-system. / This thesis work has been done in collaboration with Sweco Systems in Eskilstuna, Sweden. The purpose with this work is to investigate the ventilation in a preschool in Eskilstuna. The focus of the work is to analyze the potential energy savings of using a variable air volume system instead of a constant air volume system. An analysis is also made to investigate the economical profitability of three different scenarios. The method used to solve the problem formulation has been through gathering information, in form of scientific journals in the current problem area. Information has also been gathered through an interview and a site visit. Various software has been used in this thesis work for calculations, such as MagiCAD, IDA ICE, Sektionsdata 4.21 and Microsoft Excel. The result shows that the most energy efficient solution is a rotary heat exchanger with variable air volume control in combination with a cross-flow heat exchanger for the kitchen section. However, the most profitable solution from an economical point of view is the same system, but with constant air volume control. Sensitivity analysis shows that for a profitable variable air volume system, either the interest rate has to be lowered from 5 % to 2,56 %, the energy price needs to increase by 2,44 % yearly. Or maintenance cost for the variable air volume system needs to be lowered by 2 164 kr. The conclusion of this thesis work is that energy savings can be done with a variable air volume system. However from an economical point of view, the constant air volume is better than variable air volume for the investigated preschool. The sensitivity analysis shows that small changes are needed to make a variable air volume system profitable. The choice between the systems are influenced by certain factors. A decrease of the attendance than the dimensioned are an advantage for variable air volume systems. This is due to the fact that a constant air volume system ventilates more than needed. A higher specific fan power number are also of great importance in the choice, as more energy consumption by the fans leads to greater energy savings for variable air volume systems.

Heating, ventilation and air conditioning systems (HVAC) are the single largest consumer of energy in commercial and residential sectors. Minimizing its energy consumption without compromising indoor air quality (IAQ) and thermal comfort would result in environmental and financial benefits. Currently, most buildings still utilize constant air volume (CAV) systems with on/off control to meet the thermal loads. Such systems, without any consideration of occupancy, may ventilate a zone excessively and result in energy waste. Previous studies showed that CO₂-based demand-controlled ventilation (DCV) methods are the most widely used strategies to determine the optimal level of supply air volume. However, conventional CO₂ mass balanced models do not yield an optimal estimation accuracy. In this study, feed-forward neural network algorithm (FFNN) was proposed to estimate the zone occupancy using CO₂ concentrations, observed occupancy data and the zone schedule. The occupancy prediction result was then utilized to optimize supply fan operation of the air handling unit (AHU) associated with the zone. IAQ and thermal comfort standards were also taken into consideration as the active constraints of this optimization. As for the validation, the experiment was carried out in an auditorium located on a university campus. The results revealed that utilizing neural network occupancy estimation model can reduce the daily ventilation energy by 74.2% when compared to the current on/off control.

The overall objective of this study is, to understand how the prehistoric individual experienced her “being in the world”. This is done by examining the spatial relationships of prehistoric remains in order to understand hierarchies. The foundation of the thesis is constructed by using data from the prehistoric settlement of Letolo in Samoa (Independent State of Samoa) in West-Polynesia and Hanga Ho´onu on Rapa Nui (Easter Island) in East-Polynesia. These data are stored and analysed in a Geographical Information System (GIS). In the Samoan case the intention is to make previously unpublished surveys available. An aim is to develop a method to interpret social information from the spatial relations of built structures. It is questioned if it is possible to interpret the degree of hierarchy in a prehistoric society only from the spatial relations of features. It is concluded that such an inquiry needs to be paired with preunderstanding and analogies, such as ethnohistorical data, since it otherwise is problematic to ascribe meaning to different built structures. The thesis uses ethnohistory for preunderstanding and analogy. The thesis further examines the worldviews and structures that are shown in the repeated practice of groups in the two settlements. / Det övergripande syftet med föreliggande studie är att komma närmare den förhistoriska människans upplevelse av varat, att komma närmare hennes upplevelse av att finnas till i världen. Detta görs genom att undersöka fornlämningars spatiala relationer för att förstå  hierarkier. I uppsatsen redovisas två databaser och Geografiska Informationssystem som har konstruerats utifrån fornlämningsdata från förhistoriska bosättningar på Samoa i västpolynesien och Rapa Nui i östpolynesien. På Samoa är det Letolodalen på ön Savai´i som undersöks, och på Rapa Nui är det Hanga Ho´onu vid La Pérouse-bukten som undersöks. Uppsatsen ämnar tillgängliggöra opublicerade inventeringar av Letolo på Samoa. En intention är att utarbeta specifika kriterier för att utläsa social information från den spatiala utbredningen av fornlämningar. Arbetet ifrågasätter om det är möjligt att läsa ut graden av hierarki i ett förhistoriskt samhälle utifrån de spatiala relationerna mellan fornlämningar. Svaret är att det går om analogier och förförståelse används då det annars är problematiskt att tillskriva mening till fornlämningar. Eftersom Polynesien är väl dokumenterat utifrån ett etnohistoriskt perspektiv används analogier och förförståelse från dessa berättelser. I uppsatsen undersöks vidare mentala världar och strukturer som visar sig i gruppers upprepade praktiker i de två bosättningarna.

Indiana University-Purdue University Indianapolis (IUPUI) / Heating, ventilation, and air conditioning (HVAC) is the technology responsible to maintain temperature levels and air quality in buildings to certain standards. In a commercial setting, HVAC systems accounted for more than 50% of the total energy cost of the building in 2013 [13]. New control methods are always being worked on to improve the effectiveness and efficiency of the system. These control systems include model predictive control (MPC), evolutionary algorithm (EA), evolutionary programming (EP), and proportional-integral-derivative (PID) controllers. Such control tools are used on new HVAC system to ensure the ultimate efficiency and ensure the comfort of occupants. However, there is a need for a system that can monitor the energy performance of the HVAC system and ensure that it is operating in its optimal operation and controlled as expected. In this thesis, an air handling unit (AHU) of an HVAC system was modeled to analyze its performance using real data collected from an operating AHU using a wireless monitoring system. The purpose was to monitor the AHU's performance, analyze its key parameters to identify flaws, and evaluate the energy waste. This system will provide the maintenance personnel to key information to them to act for increasing energy efficiency. The mechanical model was experimentally validated first. Them a baseline operating condition was established. Finally, the system under extreme weather conditions was evaluated. The AHU's subsystem performance, the energy consumption and the potential wastes were monitored and quantified. The developed system was able to constantly monitor the system and report to the maintenance personnel the information they need. I can be used to identify energy savings opportunities due to controls malfunction. Implementation of this system will provide the system's key performance indicators, offer feedback for adjustment of control strategies, and identify the potential savings. To further verify the capabilities of the model, a case study was performed on an air handling unit on campus for a three month monitoring period. According to the mechanical model, a total of 63,455 kWh can be potentially saved on the unit by adjusting controls. In addition the mechanical model was able to identify other energy savings opportunities due to set point changes that may result in a total of 77,141 kWh.