Study of optimal control strategies for an energy system using thermal mass of buildings

L’étude de stratégies optimisées de contrôle-commande d'un système énergétique valorisant l'inertie thermique d’un bâtiment a pour objet d’exploiter la masse thermique de l’enveloppe et d’implémenter une stratégie optimale pour des applications de chauffage, de climatisation et d’eau chaude sanitaire. La méthode développée permet de réaliser l’optimisation de la commande en intégrant à la fois l’enveloppe du bâtiment, une pompe à chaleur et un champ de sondes. La présente thèse intègre donc, en complément de la simulation thermique dynamique de l’enveloppe, des modèles liées au champ de sonde et à la pompe à chaleur géothermique. Un outil d’optimisation des stratégies de commande, en temps réel, est élaboré en prenant en compte des objectifs en termes de précision et de temps de calcul. Cet outil permet de déterminer un profil de commande optimisé relatif au bâtiment, qui permet de réduire le coût électrique et/ou les émissions de CO2, ceci en fonction des différents paramètres relatifs au bâtiment, à son contexte climatique et aux systèmes (site, météo, enveloppe, tarifs, efficacité des systèmes…). Les algorithmes développés sont basés sur deux méthodes de résolution du problème d’optimisation : la méthode directe et la méthode indirecte. Ces deux méthodes fournissent des résultats prometteurs au niveau du temps de calcul et de la précision. La méthode directe est plus pertinente pour l’application en temps réel : elle est plus rapide, et plus simple et nécessite un temps de développement inférieur à la méthode indirecte. De plus, une étude a permis de comparer, pour une maison individuelle, les pourcentages de gain en fonction des zones climatiques considérées et du niveau d’isolation de l’enveloppe.The study of optimised control strategies of an energy system leveraging the thermal inertia of a building aims at exploiting the thermal mass of the envelope and implementing an optimal strategy for heating, air conditioning and domestic hot water applications. The developed method makes it possible to optimise the control integrating the envelope, a heat pump and a vertical ground heat exchanger. This thesis incorporates therefore, in addition to building energy simulation, models related to the geothermal borehole field and the heat pump. A control strategy optimisation tool, in real time, is elaborated taking into account objectives in terms of precision and computation time. This tool makes it possible to determine an optimised control profile relating to the building, which makes it possible to reduce the electrical cost and/or GHG emissions, according to the various parameters related to the building, its context and the systems (site, weather, envelope, tariffs, system efficiency, etc.). The developed algorithms are based on two methods of solving the optimisation problem: the direct method and the indirect method. These two methods provide promising results in terms of computation time and accuracy. The direct method is more relevant for the real-time application, as it is faster, and simpler, and requires less development time than the indirect method. In addition, a study made it possible to compare the percentages of gain according to various climate zones and level of insulation of the envelope

Optimal Control Strategies for Energy Production Systems using Buildings Thermal Mass

International audienceThe aim of this study is to develop real-time energy management strategies for HVAC systems taking into account the heat storage in building thermal mass. In fact, thermal energy production represents up to 50 % of building's total energy consumption and 75 % of Greenhouse Gases (GHG) emissions. Different systems and storage methods can be integrated to reduce the cost and the GHG emissions related to heating, cooling and Domestic Hot Water (DHW) production in buildings. In this context, multiple studies have developed optimal control systems (such as Model Predictive Control) for optimising thermal production and/or storage systems. The results presented in these studies showed a wide range of reduction rates due to different hypotheses, models, methods and systems taken into consideration. In real time optimisation, the building model is usually separated from the thermal system. In this study, a reduced model and a continuous optimisation method were used to minimise the cost of the building's heating. The applied strategy combined the building model and thermal mass with a Ground Source Heat Pump (GSHP) and a Borehole Thermal Energy Storage (BTES). This first approach showed promising results by reducing the cost between 10 % and 15 %. This method will be used to combine different systems and improve their performance in real-time. Key Innovations Real time simultaneous multi-system optimisation using Pontryagin Minimum Principal. BTES and GSHP operation optimisation taking into consideration building thermal mass energy storage under variable electricity pricing. Practical Implications Real time optimal control is an interesting solution for cost and GHG emissions reduction. When it comes to such simulations, the results can vary on the models, hypotheses and algorithms used. Every project should be analysed separately, and the building properties taken into consideration in the application of the optimal control

Light oxygenated volatile organic compound concentrations in an Eastern Mediterranean urban atmosphere rivalling those in megacities

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Cold‐evoked potentials in clinical practice: A head‐to‐head contrast with laser‐evoked responses

International audienceAbstractBackground: Innocuous cooling of the skin activates cold-specific Aδ fibres, and hence, the recording of cold-evoked potentials (CEPs) may improve the objective assessment of human thermo-nociceptive function. While the feasibility of CEP recordings in healthy humans has been reported, their reliability and diagnostic use in clinical conditions have not been documented.Methods: Here, we report the results of CEP recordings in 60 consecutive pa- tients with suspected neuropathic pain, compared with laser-evoked potentials (LEPs) which are the gold standard for thermo-algesic instrumental assessment. Results: CEP recording was a well-tolerated procedure, with only ~15 min of sur- plus in exam duration. The reproducibility and signal-to-noise ratio of CEPs were lower than those of LEPs, in particular for distal lower limbs (LLs). While laser responses were interpretable in all patients, CEPs interpretation was inconclu- sive in 5/60 because of artefacts or lack of response on the unaffected side. Both techniques yielded concordant results in 73% of the patients. In 12 patients, CEPs yielded abnormal values while LEPs remained within normal limits; 3 of these patients had clinical symptoms limited to cold sensations, including cold-heat transformation.Conclusions: CEPs appear as a useful technique for exploring pain/temperature systems. Advantages are low cost of equipment and innocuity. Disadvantages are low signal-to-noise ratio for LL stimulation, and sensitivity to fatigue/habitu- ation. Joint recording of CEPs and LEPs can increase the sensitivity of neuro- physiological techniques to thin fibre- spinothalamic lesions, in particular, when abnormalities of cold perception predominate.Significance: Recording of cold-evoked potentials is a well-tolerated, inexpen- sive and easy-to-use procedure that can be helpful in the diagnosis of abnormali- ties in the thin fibre- spinothalamic pathways. Supplementing LEPs with CEPs allows consolidating the diagnosis and, for some patients suffering from symp- toms limited only to cold, CEPs but not LEPs may allow the diagnosis of thin fibre pathology. Optimal CEP recording conditions are important to overcome the low signal-to-noise ratio and habituation phenomena, which are less favourable than with LEPs

Sympathetic skin response as an objective tool to estimate stimulus-associated arousal in a human model of hyperalgesia

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Source apportionment vs. emission inventories of non-methane hydrocarbons (NMHC) in an urban area of the Middle East: local and global perspectives

International audienceWe applied the positive matrix factorization model to two large data sets collected during two intensive measurement campaigns (summer 2011 and winter 2012) at a suburban site in Beirut, Lebanon, in order to identify NMHC (non-methane hydrocarbons) sources and quantify their contribution to ambient levels. Six factors were identified in winter and five factors in summer. PMF-resolved source profiles were consistent with source profiles established by near-field measurements. The major sources were traffic-related emissions (combustion and gasoline evaporation) in winter and in summer accounting for 51 and 74 wt %, respectively, in agreement with the national emission inventory. The gasoline evaporation related to traffic source had a significant contribution regardless of the season (22 wt % in winter and 30 wt % in summer). The NMHC emissions from road transport are estimated from observations and PMF results, and compared to local and global emission inventories. The PMF analysis finds reasonable differences on emission rates, of 20-39 % higher than the national road transport inventory. However, global inventories (ACCMIP, EDGAR, MACC-ity) underestimate the emissions up to a factor of 10 for the transportation sector. When combining emission inventory to our results, there is strong evidence that control measures in Lebanon should be targeted on mitigating the NMHC emissions from the traffic-related sources. From a global perspective , an assessment of VOC (volatile organic compounds) an-thropogenic emission inventories for the Middle East region as a whole seems necessary as these emissions could be much higher than expected at least from the road transport sector

Exploring the seasonal NMHC distribution in an urban area of the Middle East during ECOCEM campaigns: very high loadings dominated by local emissions and dynamics

Non-methane hydrocarbons play an important role in the formation of photochemical oxidants such as ozone. We investigate factors controlling the distribution of non-methane hydrocarbons in an urban area of the Middle East. The study highlights the importance of local emissions and atmospheric dynamics, and the limited effect of photochemistry at the measurement site. Abstract Measurements of over 70 C2-C16 non-methane hydrocarbons (NMHCs) were conducted in suburban Beirut (1.3 million inhabitants) in summer 2011 and winter 2012 during the Emission and Chemistry of Organic Carbon in the East Mediterranean (ECOCEM) field campaign. The levels of NMHCs observed exceeded by a factor of two in total volume the levels found in northern mid-latitude megacities (Paris and Los Angeles), especially for the unburned fossil fuel fraction. Regardless of the season, the major compounds, explaining 50% of the concentrations, were toluene, isopentane, butane, m,p-xylenes, propane and ethylene, emitted by mobile traffic and gasoline evaporation sources. Most NMHCs show a distinct seasonal cycle, with a summer maximum and a winter minimum, unlike seasonal cycles usually observed in the northern mid-latitude urban areas. We show that NMHC distribution is mainly driven by strong local emissions and local atmospheric dynamics, with no clear evidence of photochemical removal in summer or influence from long-range transport

OntoH2G: A semantic model to represent building infrastructure and occupant interactions

10th International Conference on Sustainability and Energy in Buildings, SEB 2018 -- 24 June 2018 through 26 June 2018 -- 221679In order to reduce the energy gap originated by the difference between existing tools estimations and real energy consumption, HIT2GAP European H2020 project aims at advancing on building control tools by providing a newer decision-making technology. Technically, HIT2GAP offers a platform inspired by previous reference architectures (e.g., Haystack) and complements them through a knowledge-based model, called OntoH2G, to store building information under a common vocabulary and consequently to enable fine-grained vision of the building with its equipment and occupants. OntoH2G advances over existing models on two main aspects: (i) being compliant with well-known ontologies in different domains in order to cover all energy building concepts, and (ii) its ability to represent user/occupant behavior, preferences, and interactions. In this paper, we present the main features of OntoH2G and describe how the well-known ontologies have been aligned in OntoH2G. © Springer Nature Switzerland AG 2019.680708Acknowledgements. The HIT2GAP project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 680708. -

Quantitative cancer risk assessment and local mortality burden for ambient air pollution in an eastern Mediterranean City

International audienc

Composition and variability of gaseous organic pollution in the port megacity of Istanbul: source attribution, emission ratios and inventory evaluation

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