hvac thesis

Exploration of Intelligent HVAC Operation Strategies for Office Buildings

Commercial buildings not only have significant impacts on occupants’ well-being, but also contribute to more than 19% of the total energy consumption in the United States. Along with improvements in building equipment efficiency and utilization of renewable energy, there has been significant focus on the development of advanced heating, ventilation, and air conditioning (HVAC) system controllers that incorporate predictions (e.g., occupancy patterns, weather forecasts) and current state information to execute optimization-based strategies. For example, model predictive control (MPC) provides a systematic implementation option using a system model and an optimization algorithm to adjust the control setpoints dynamically. This approach automatically satisfies component and operation constraints related to building dynamics, HVAC equipment, etc. However, the wide adaptation of advanced controls still faces several practical challenges: such approaches involve significant engineering effort and require site-specific solutions for complex problems that need to consider uncertain weather forecast and engaging the building occupants. This thesis explores smart building operation strategies to resolve such issues from the following three aspects.

First, the thesis explores a stochastic model predictive control (SMPC) method for the optimal utilization of solar energy in buildings with integrated solar systems. This approach considers the uncertainty in solar irradiance forecast over a prediction horizon, using a new probabilistic time series autoregressive model, calibrated on the sky-cover forecast from a weather service provider. In the optimal control formulation, we model the effect of solar irradiance as non-Gaussian stochastic disturbance affecting the cost and constraints, and the nonconvex cost function is an expectation over the stochastic process. To solve this optimization problem, we introduce a new approximate dynamic programming methodology that represents the optimal cost-to-go functions using Gaussian process, and achieves good solution quality. We use an emulator to evaluate the closed-loop operation of a building-integrated system with a solar-assisted heat pump coupled with radiant floor heating. For the system and climate considered, the SMPC saves up to 44% of the electricity consumption for heating in a winter month, compared to a well-tuned rule-based controller, and it is robust, imposing less uncertainty on thermal comfort violation.

Second, this thesis explores user-interactive thermal environment control systems that aim to increase energy efficiency and occupant satisfaction in office buildings. Towards this goal, we present a new modeling approach of occupant interactions with a temperature control and energy use interface based on utility theory that reveals causal effects in the human decision-making process. The model is a utility function that quantifies occupants’ preference over temperature setpoints incorporating their comfort and energy use considerations. We demonstrate our approach by implementing the user-interactive system in actual office spaces with an energy efficient model predictive HVAC controller. The results show that with the developed interactive system occupants achieved the same level of overall satisfaction with selected setpoints that are closer to temperatures determined by the MPC strategy to reduce energy use. Also, occupants often accept the default MPC setpoints when a significant improvement in the thermal environment conditions is not needed to satisfy their preference. Our results show that the occupants’ overrides can contribute up to 55% of the HVAC energy consumption on average with MPC. The prototype user-interactive system recovered 36% of this additional energy consumption while achieving the same overall occupant satisfaction level. Based on these findings, we propose that the utility model can become a generalized approach to evaluate the design of similar user-interactive systems for different office layouts and building operation scenarios.

Finally, this thesis presents an approach based on meta-reinforcement learning (Meta-RL) that enables autonomous optimal building controls with minimum engineering effort. In reinforcement learning (RL), the controller acts as an agent that executes control actions in response to the real-time building system status and exogenous disturbances according to a policy. The agent has the ability to update the policy towards improving the energy efficiency and occupant satisfaction based on the previously achieved control performance. In order to ensure satisfactory performance upon deployment to a target building, the agent is trained using the Meta-RL algorithm beforehand with a model universe obtained from available building information, which is a probability measure over the possible building dynamical models. Starting from what is learned in the training process, the agent then fine-tunes the policy to adapt to the target building based on-site observations. The control performance and adaptability of the Meta-RL agent is evaluated using an emulator of a private office space over 3 summer months. For the system and climate under consideration, the Meta-RL agent can successfully maintain the indoor air temperature within the first week, and result in only 16% higher energy consumption in the 3 rd month than MPC, which serves as the theoretical upper performance bound. It also significantly outperforms the agents trained with conventional RL approach.

National Science Foundation

Center for high performance buildings, degree type.

• Doctor of Philosophy
• Civil Engineering

Campus location

• West Lafayette

Evaluation of performance of an air handling unit using wireless monitoring system and modeling

Embargo lift date, committee chair, committee members, degree year, journal title, journal issn, volume title.

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.

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Showing result 1 - 5 of 44 swedish dissertations containing the words thesis on hvac .

1. Predicting flow-generated noise from HVAC components

Author : Oscar Kårekull ; Mats Åbom ; Gunilla Efraimsson ; Joachim Golliard ; KTH ; [] Keywords : TEKNIK OCH TEKNOLOGIER ; ENGINEERING AND TECHNOLOGY ; flow noise ; noise prediction ; HVAC ; flödesalstrat ljud ; bullerprediktion ; HVAC ;

Abstract : More energy efficient fans, i.e. larger sizes running at lower speeds, in Heating Ventilation and Air Conditioning (HVAC) systems decrease the fan noise and increase the importance of flow generated noise in other system components, e.g. READ MORE

2. Energy use and environmental impact from hotels on Adriatic Coast in Croatia : current status and future possibilities for HVAC systems

Author : Vlasta Zanki Alujevic ; Per Lundqvist ; Dagnia Blumberga ; KTH ; [] Keywords : TEKNIK OCH TEKNOLOGIER ; ENGINEERING AND TECHNOLOGY ; HVAC systems ; hotels ; energy performance ; energy efficiency ; environmental savings ; energy audit ; system approach ; sustainable energy systems ; Environmental engineering ; Miljöteknik ;

Abstract : This thesis analyses a specific type of energy usage system, “energy usage in hotels”, and how this system behaves. In order to evaluate the current state of energy use in hotels, an energy audit questionnaire was developed and conducted among 31,5% of hotels on the Adriatic coast. READ MORE

3. Air - for Health and Comfort, An Analysis of HVAC Systems' Performance in Theory and Practice

Author : Fredrik Engdahl ; Avdelningen för Byggnadsfysik ; [] Keywords : TEKNIK OCH TEKNOLOGIER ; ENGINEERING AND TECHNOLOGY ; Byggnadsteknik ; Building construction ; indoor air quality ; HVAC ; infiltration ; ventilation ; VAV ;

Abstract : One part of the objective is to analyze how different ventilation systems perform in practice when it comes to supplying and exhausting designed air flow in different outdoor and indoor conditions. The other part is to analyze the design criterias and the energy use of a variable air volume system based on controlled static pressure at the branch duct level and supplying outdoor air only. READ MORE

4. Energy Efficiency in Shopping Malls : Some Aspects Based on a Case Study

Author : Sofia Stensson ; Jan-Olof Dalenbäck ; Per Fahlén ; Monica Axell ; Jeffrey Spitler ; Sweden Chalmers University of Technology ; [] Keywords : TEKNIK OCH TEKNOLOGIER ; ENGINEERING AND TECHNOLOGY ; Shopping mall ; energy use ; energy efficiency ; HVAC system ; load patterns ; case study ; regulatory requirements ; building code ; and energy declarations ;

Abstract : The building sector accounts for approximately 40 percent of our energy use. To reach existing environmental targets energy use will have to be reduced in all building types. At the European level, the main legislative instrument for improving the energy efficiency of the building stock is the Energy Performance of Buildings Directive (EPBD). READ MORE

5. Demand based control of indoor climate in office buildings. Design of local and central feed-forward control systems for high comfort, low energy use and low peak power

Author : Mattias Gruber ; Chalmers tekniska högskola ; [] Keywords : TEKNIK OCH TEKNOLOGIER ; ENGINEERING AND TECHNOLOGY ; demand based control ; IAQ ; central control ; local control ; disturbance rejection ; thermal climate ; HVAC ; energy efficiency ; feed-forward ; Building services engineering ; office buildings ;

Abstract : In this work, a number of novel strategies for controlling the heating, ventilation and air-conditioning (HVAC) systems in office buildings have been designed and evaluated. The purpose of the control strategies is to improve the match between what is supplied by the HVAC-systems and what is required to achieve a desirable indoor climate in the building. READ MORE

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Dissertations / Theses on the topic 'HVAC; Building environments; Ventilation'

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Lugg, Andrew. "Energy and cost efficient fuzzy environmental services control strategies for achieving high standards of indoor environmental quality and human comfort." Thesis, Cranfield University, 1999. http://hdl.handle.net/1826/4198.

Abbass, Omed Akber. "Ozone Interaction with Indoor Building Materials and HVAC Filters." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3771.

Shi, Hongsen. "Building Energy Efficiency Improvement and Thermal Comfort Diagnosis." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555110595177379.

Sui, Di. "Characterization of HVAC operation uncertainty in EnergyPlus AHU modules." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51911.

Sun, Jian Reddy Agami T. Dr. "Methodology for adapting rigorous simulation programs to supervisory control of building HVAC & R systems: simulation, calibration and optimization /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/381.

Thompson, Glendon Raymond. "Business reasons for utilizing renewable energy applications in facilities to assist in extending the life of the heating ventilation and air conditioning systems." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22631.

Martinovic, Zarko. "Design a PV – system for a large building." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17539.

Drach, Patricia Regina Chaves. "Computational modelling and numerical simulation in architecture aiming at comfort of building environments." Laboratório Nacional de Computação Científica, 2007. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=138.

Van, Rensburg Johann Francois. "Developing ESCO procedures for large telecommunication facilities using novel simulation techniques / J.F. van Rensburg." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1693.

Stankevica, Galina. "Commissioning of the HVAC-plant in a large office building designed with an underfloor ventilation system including input into what should be emphasized when evaluating the total system is to be done." Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10760.

The following paper presents HVAC system commissioning activities, highlighting the most critical techniques and features to consider when commissioning the underfloor air distribution (UFAD) system. UFAD systems are non-standard and unique and therefore a special attention is needed to some issues and situations specific only for UFAD installations, e.g. coordination of the raised access floor, carpet and furnishings, temperature stratification etc. Some of the most important tests to be performed during commissioning of UFAD systems, are the air leakage, air stratification and thermal decay testing. In order to achieve successful operation of UFAD, the active participation of all involved parties, e.g. architects, interior designers, HVAC designers, contractors etc. is needed since the very beginning of the project. Commissioning of UFAD just requires a discipline, structured approach and commitment from all participants involved. The practical study involved assessment of expected UFAD performance at the Sparebank kvartalet office building complex in Trondheim, Norway. The underfloor plenum was not properly sealed, creating a significant risk of future energy waste. The openings in the raised access floor construction also lead to the dust and dirt accumulation in the plenum. This in its turn would not only impair indoor air quality, but could also lead to the malfunction of mechanical equipment installed in the plenum. Trying to seal the plenum after laying down the carpet was found to be difficult, costly and time consuming. Even though relatively good air distribution in the entire floor was achieved, some diffusers (automatically controlled) are located too close to the workstations and it will be probably needed to rearrange their layout in order to avoid draught complaints by occupants. The easier commissioning and better performance of UFAD in Sparebank Kvartalet could actually be achieved in a less time consuming and costly way if the commissioning would start early in the pre-design phase, with a well established commissioning plan.

Bouwer, Werner. "Designing a dynamic thermal and energy system simulation scheme for cross industry applications / W. Bouwer." Thesis, North-West University, 2004. http://hdl.handle.net/10394/592.

Drach, Patricia Regina Chaves. "Modelagem computacional e simulação numérica em arquitetura visando conforto emaAmbientes construídos." Laboratório Nacional de Computação Científica, 2007. https://tede.lncc.br/handle/tede/66.

Merabtine, Abdelatif. "Modélisation Bond Graphs en vue de l'Efficacité Énergétique du Bâtiment." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0121/document.

"Modelling and evaluation of an energy efficient heating ventilation and air conditioning (HVAC) system in an office building." Thesis, 2014. http://hdl.handle.net/10210/8817.

Tanskyi, Oleksandr. "Analysis of Innovative HVAC System Technologies and Their Application for Office Buildings in Hot and Humid Climates." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8917.

(5930906), Jacob J. Torres. "The Biowall Field Test Analysis and Optimization." Thesis, 2019.

A residential botanical air filtration system (Biowall) to investigate the potential for using phytoremediation to remove contaminants from indoor air was developed. A full scale and functioning prototype was installed in a residence located in West Lafayette, Indiana. The prototype was integrated into the central Heating, Ventilating, and Air Conditioning (HVAC) system of the home. This research evaluated the Biowall operation to further its potential as an energy efficient and sustainable residential air filtration system.

The main research effort began after the Biowall was installed in the residence. A field evaluation, which involved a series of measurements and data analysis, was conducted to identify treatments to improve Biowall performance. The study was conducted for approximately one year (Spring 2017-Spring 2018). Based on the initial data set, prioritization of systems in need of improvement was identified and changes were imposed. Following a post-treatment testing period, a comparison between the initial and final performances was completed with conclusions based on this comparison.

The engineering and analysis reported in this document focus on the air flow path through the Biowall, plant growth, and the irrigation system. The conclusions provide an extensive evaluation of the design, operation, and function of the Biowall subsystems under review.

Journal of Materials Chemistry B

Enhancement in the induction heating efficacy of sol–gel derived sio 2 –cao–na 2 o–p 2 o 5 bioglass-ceramics by incorporating magnetite nanoparticles.

* Corresponding authors

a Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, India E-mail: [email protected]

b Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, India

c Department of Science and Humanities, National Institute of Technology Nagaland, India

d Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan, Republic of Korea

Magnetite (Fe 3 O 4 ) nanoparticle (MNP)-substituted glass-ceramic (MSGC) powders with compositions of (45 − x )SiO 2 –24.5CaO–24.5Na 2 O–6P 2 O 5 – x Fe 3 O 4 ( x = 5, 8, and 10 wt%) have been prepared by a sol–gel route by introducing Fe 3 O 4 nanoparticles during the synthesis. The X-ray diffraction patterns of the as-prepared MSGC nanopowders revealed the presence of combeite (Na 2 Ca 2 Si 3 O 9 ), magnetite, and sodium nitrate (NaNO 3 ) crystalline phases. Heat-treatment up to 700 °C for 1 h resulted in the complete dissolution of NaNO 3 along with partial conversion of magnetite into hematite (α-Fe 2 O 3 ). Optimal heat-treatment of the MSGC powders at 550 °C for 1 h yielded the highest relative percentage of magnetite (without hematite) with some residual NaNO 3 . The saturation magnetization and heat generation capacity of the MSGC fluids increased with an increase in the MNP content. The in vitro bioactivity of the MSGC pellets was evaluated by monitoring the pH and the formation of a hydroxyapatite surface layer upon immersion in modified simulated body fluid. Proliferation of MG-63 osteoblast cells indicated that all of the MSGC compositions were non-toxic and MSGC with 10 wt% MNPs exhibited extraordinarily high cell viability. The MSGC with 10 wt% MNPs demonstrated optimal characteristics in terms of cell viability, magnetic properties, and induction heating capacity, which surpass those of the commercial magnetic fluid FluidMag-CT employed in hyperthermia treatment.

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Nitu, R. Fopase, L. M. Pandey, K. P. Hazarika, J. P. Borah, R. K. Singh and A. Srinivasan, J. Mater. Chem. B , 2024, Advance Article , DOI: 10.1039/D3TB03014H

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