A Practical Data-Driven Multi-Model Approach to Model Predictive Control: Results from Implementation in an Institutional Building

Model-based Predictive Control (MPC) is an effective solution to improve building controls. It consists of the use of weather and occupancy forecasts along with a control-oriented model to predict the behaviour of the building a few hours or days ahead, and thus optimize the operation of its systems. Although the potential of MPC is widely recognized, and plentiful operational data is often available, the development of a model requires a great deal of effort, significant technical expertise and knowledge of building systems. The challenge of creating a model is a hurdle that makes the on-site implementation of MPC in buildings relatively rare. This study tackles the development of a multi-model approach to optimize the operation of electric and natural gas boilers in an institutional building to reduce greenhouse gas (GHG) emissions while maintaining the required level of comfort. This methodology leverages Machine Learning techniques to rapidly develop and calibrate control-oriented models using a limited number of input variables (indoor air temperature and temperature set-points, weather conditions, power meter data). The proposed multi-model approach consists of five models used to estimate the building total heating demand, the electric baseload, the natural gas boiler power, and the indoor air temperature under free floating conditions and during warming-up periods in the morning. The models are calibrated and validated with operational data and they are then used to optimize the transition between nighttime and daytime indoor air temperature. Since these are black-box models that require only a basic understanding of the building system and a few inputs, the model development was considerably reduced while the modularity of the proposed method makes it flexible. Such an approach could therefore be easily replicated in other buildings equipped with similar pieces of equipment. This methodology has been implemented in a Canadian institutional building, located in Varennes (QC). Results in 2020-21 showed that the COVID-19 pandemic has significantly impacted building performance and reduced energy use, thus creating a new baseline. The MPC strategy allowed to achieve an additional 20.2% GHG emission reduction compared to this new baseline while thermal comfort was improved. Nevertheless, energy costs increased, which was mainly due to the impact of the pandemic, which eventually made the pre-COVID-19 model and optimization parameters outdated; lower costs are expected with model recalibration, currently ongoing

Optimisation structurelle des systèmes énergétiques

L’essor des énergies renouvelables a pris de l’ampleur ces dernières années pour faire face aux problèmes environnementaux liés à la consommation d’énergies fossiles. Ces énergies sont grandement mises à profit dans les secteurs résidentiel et commercial et de nombreux systèmes ont été proposés pour répondre à la demande énergétique des bâtiments. Améliorer le rendement et l’utilisation de ces unités, autrement dit améliorer la gestion de l’énergie, apparaît alors essentiel afin de réduire l’empreinte écologique de l’Homme sur la planète. Toutefois, l’intégration des systèmes est un problème très complexe à résoudre ; en effet, il fait intervenir le nombre d’unités, leur technologie, leur taille, leurs conditions de fonctionnement et la façon de les connecter entre elles. La multitude de solutions proposées met ainsi en relief le manque d’une analyse systématique permettant de comparer leurs performances. Cette démarche est essentielle afin d’évaluer les différents arrangements, quel que soit le critère, et de déterminer l’équipement optimal selon le contexte économique, le climat d’étude et l’espace disponible pour installer les unités. Ainsi, l’objectif est de présenter une telle méthode, soit l’optimisation structurelle des systèmes énergétiques. Elle servira à identifier les différents arrangements possibles entre unités et à comparer leurs performances dans le but de choisir l’équipement optimal. Les combinaisons ont été soumises à un ensemble de contraintes environnementales (climat d’étude), structurelles (espace disponible) et économiques et les critères de choix ont tenu compte des aspects énergétiques, économiques et écologiques. Pour ce faire, en plus des analyses énergétique et économique clas-siques, le concept d’exergie a également été étudié et appliqué à l’équipement. Cependant, l’approche par les logiciels usuels est peu évidente, de par la complexité des systèmes intégrés et les temps de calculs particulièrement longs. Il est clair que le travail d’optimisation au complet constitue une tâche considérable et l’intérêt de cette thèse est d’instaurer les bases de l’optimisation avec des outils appropriés. Une revue exhaustive de l’équipement, plus particulièrement les panneaux photovoltaïques, les capteurs solaires, les pompes à chaleurs et les réservoirs de stockage, a tout d’abord été effectuée de manière à envisager l’ensemble des possibilités de combinaisons des unités pour répondre à la demande énergétique des bâtiments. Des modélisations énergétiques et exergétiques de l’équipement, adaptées au problème d’optimisation, ont été effectuées et appliquées à deux scénarios particuliers : a) une pompe à chaleur solaire avec stockage de glace et réservoir d’eau chaude et b) une pompe à chaleur utilisant l’air ambiant associée à des panneaux photovoltaïques.----------Abstract The development of renewable energies is growing over the last decade to face environmental issues due to the world fossil fuel consumption increase. These energies are highly involved in houses and commercial buildings and numerous systems have been proposed to meet their energy demand. Therefore, improving both efficiency and use of systems, i.e. improving energy man-agement, appears essential to limit the ecological footprint of humanity on the planet. However, system integration yields a very complex problem to be solved due to the large number of units and theirs technology, size, working conditions and interconnections. This situation highlights the lack of systematic analysis for comparing integrated system performance and for correctly point-ing out their potential. As a result, the objective of this thesis is to develop and to present such a method, in other words the structural optimization of energy systems. It will be helpful to choose the optimal equipment by identifying all the possibilities of system arrangements and for compar-ing their performance. Combinations have then been subjected to environmental (climate), struc-tural (available area) and economical constrains while assessment criteria have considered both energy, economic and ecological aspects. For that reason, as well as energy and economic anal-yses, the exergy concept has also been applied to the equipment. Nevertheless, the high degree of complexity of integrated systems and the tedious numerical calculations make the resolution by using standard software very difficult. It is clear that the whole optimization project would be considerable and the aim is to develop models and optimization tools. First of all, an exhaustive review of energy equipment including photovoltaic panels, solar collectors, heat pumps and thermal energy storage systems, has been performed. Afterwards, energy and exergy models have been developed and tested for two specific energy scenarios: a) a solar assisted heat pump using ice and warm water storages and b) an ambient air heat pump associated to photovoltaic panels. A superstructure has then been constructed to account for every system combination possibility. The different energy paths have been illustrated while irreversibility along every path is identi-fied. Thus, it allows the system operation to be clearly understood. Besides, an exergy diagram has been developed and permits energy and exergy assessment of system and system arrange-ments to be not only identified but also quantified and separated depending on their (renewable or non-renewable) source. Finally, dimensions and operation variables have been optimized accord-ing to exergy and economic criteria for the aforementioned scenarios; the potential of each ener-gy option has been estimated and yield a better energy management to be reached

Preliminary Assessment of a Weather Forecast Tool for Building Operation

Although the potential of model predictive control (MPC) for the operation of buildings is widely recognized, as of today its adoption has been rather limited. This is partly due to the lack of user-friendly software tools for MPC, such as tools to facilitate the incorporation of forecast information in building automation systems. In view of this, CanmetENERGY, a research centre of Natural Resources Canada, has developed CanMETEO, a software tool free of charge aimed at obtaining weather forecast data and make it available in a useful and practical format for building operators. CanMETEO, which was released officially in August 2017, uses raw data produced by the Meterological Service of Environment Canada. This data, with high spatial resolution (e.g., 2 km x 2 km grids, and even denser for urban areas) enables the possibility of obtaining forecasts for very specific locations in the Canadian territory. Hundreds of weather variables (such as temperature, humidity, wind speed, cloud cover, among many others) are available for each point, which can be selected by the user via a graphical interface. The data is converted from GRIB files (a standard binary format used by meteorologists) into comma-separated value (CSV) files, which can be easily accessed. New forecasts become available every 6 hours, with a prediction horizon of 48 hours at hourly time steps; the retrieval of new weather forecasts can be setup in order to be performed automatically. These continuously updated CSV files may then be easily incorporated into building operation algorithms or simple optimization routines. Once the basic variables are obtained, post-processing calculations are applied in order to estimate solar irradiance on any given plane required by the user, for example, building façades and building-integrated photovoltaic panels. This feature also makes it possible to estimate the effect of solar gains on the thermal response of a building, and to estimate the output of photovoltaic panels. A preliminary evaluation of the tool, based on on-site measurements, is presented in this paper. It is expected that CanMETEO (currently used by Canadian research centre and universities) will provide one further step to the widespread adoption of predictive control as a viable, popular solution in building operation

Segmentation du contour de l'endocarde sur des séquences d'images d'échographie cardiaque

- La segmentation d'images échocardiographiques fait l'objet de nombreuses recherches. Cet article propose une méthode utilisant les Modèles Actifs de Mouvement et d'Apparence (AAMM) combinés avec une prise en compte de la sémantique de l'image. Les AAMM peuvent modéliser les différents paramètres de l'image comme la forme du ventricule gauche, sa texture interne et l'aspect temporel des images. Concernant la sémantique de l'image, nous avons inclus la texture du myocarde dans le modèle. L'écart entre la segmentation experte et la segmentation automatique a ensuite été déterminé par des mesures telles que la mesure de Vinet et la distance de Hamming et des mesures morphologiques. Nous avons donc pu vérifier que nos résultats sont proches de la segmentation experte

Apical aneurism and myocardial bridging in a patient with hypertrophic cardiomyopathy: Association or consequence of the myocardial bridging?

The identification of high-risk patients with hypertrophic cardiomyopathy (HC) for primary prevention of sudden cardiac death (SCD) remains a challenging issue, since major risk factors sometimes lack specificity. We report the case of a patient with HC and association of apical aneurysm and myocardial bridging who had been initially not implanted because she had only one major risk factor. She subsequently experienced a sustained ventricular tachycardia that finally motivated the implantation. We conclude that it is never an easy decision to implant a preventive implantable cardioverter-defibrillator (ICD). Nevertheless, additional criteria for a better selection of patients who would benefit from an ICD implant are certainly useful

Evaluation of analytical methods for parameter extraction of PV modules

© 2017 The Authors. Published by Elsevier Ltd. A review and evaluation of the main analytical techniques for parameters extraction of photovoltaic (PV) modules with due account taken of their applications in modelling photovoltaic systems is presented. Six prevalent analytical methods are investigated and assessed using software tools, which have been developed to extract the required parameters of some commercially available PV modules using these methods. The results were subsequently compared with those obtained using well-established numerical methods. It is shown that, despite the fact that analytical methods can involve a fair amount of approximations, some analytical methods can compete in terms of accuracy with their numerical counterparts with much reduced computational complexity. .Published versio

Postinfarction ventricular septal rupture: Early repair through the right atrial approach

AbstractObjective: Early repair of posterior ventricular septal rupture associated with myocardial infarction by means of transinfarct ventriculotomy is technically challenging and can be associated with significant mortality and morbidity. An alternative route of exposing the septum is through the right atrium. This technique, which avoids direct incision of the ventricle in select patients, reduces postrepair bleeding and impairment of ventricular contractile function. Methods: The results of 12 patients operated on over a 20-year period were reviewed and analyzed. Late follow-up was obtained in all patients who survived the operation. There were 9 men and 3 women, with a mean age of 69.9 years. The mean time between acute myocardial infarction and surgery was 7.3 days (range, 2-16 days). Six patients were in New York Heart Association class IV, and 3 patients presented for surgery in cardiogenic shock. One patient had previously undergone a coronary artery bypass. The surgical technique included a standard sternotomy approach with a transatrial approach to the septal rupture. In all patients the septal rupture was repaired with a Dacron patch. Results: There were 3 early deaths and 1 late death; one patient was reoperated on for a residual shunt. Postoperative complications included low cardiac output, acute renal tubular necrosis, and supraventricular arrhythmia. Eight patients are alive and undergoing echocardiographic investigation, and only 1 patient had a small residual shunt. Conclusion: Our experience shows that a posterior ventricular septal rupture can be safely repaired through a transatrial approach. Avoiding additional damage to the ventricle, it reduces the risks of the postoperative bleeding and enhances survival. (J Thorac Cardiovasc Surg 2000;119:784-9

Primary prevention with a defibrillator: are therapies always really optimized before implantation?

AIMS:Left ventricle ejection fraction (LVEF) ≤ 30-35% is widely accepted as a cut-off for primary prevention with an implantable cardiac defibrillator (ICD) in patients with both ischaemic and non-ischaemic cardiomyopathy supposedly on optimal medical therapy. This study reports evolutions of LVEF and treatments of patients implanted in our institution with an ICD for primary prevention of sudden death, after 2 years of follow-up. METHODS AND RESULTS: Among 84 patients with LVEF under 35% implanted between 2005 and 2007, 28 (33%) had improved their LVEF >35% after the 2 years of follow-up. During this period, even if Beta-blockers (98%) and renin-angiotensin system (RAS) blockers (95%) were already initially prescribed, treatments were significantly optimized with improvement of maximal doses of beta-blockers and RAS blockers at 2 year follow-up compared with initial prescription (62 vs. 37% and 68 vs. 45%, respectively). In patients with improved LVEF, a trend toward a better treatment optimization and revascularization procedures (in the sub-group of ischaemic patients) were observed compared with non-improved LVEF patients. CONCLUSIONS: In our study of patients with prophylactic ICD, one-third of them have improved their LVEF after a 2 year follow-up. Despite an optimal medical therapy at the time of implantation, we were able to further improve the maximal treatment doses after implantation. This study highlights the issue of what should be considered as \u27optimal\u27 therapy and the possibility of improvement of LVEF related to a real optimized treatment before implantation