About
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Introduction
Dr. Zuo's research focuses on modeling and simulation of smart, sustainable and resilient buildings, communities and cities. He is one of the major contributors of the open source Fast Fluid Dynamics and Modelica Buildings library. Visit his lab website: https://sites.psu.edu/sbslab for more information.
Publications
Publications (200)
Building-to-grid (B2G) integration transforms buildings into active components of the electricity grid, enhancing dynamic energy management and optimizing usage to reduce operational costs and carbon emissions. However, existing modeling tools for building and power systems often overlook or oversimplify the interactions between power system dynami...
Despite their crucial role in supplying heat and power to universities, industries, and healthcare facilities, many steam-based district heating systems (DHS) still rely on outdated control methods. Among these, multi-central plant DHS are particularly challenging due to the complexities of coordinating multiple plants, optimizing load distribution...
The U.S. buildings sector contributes 30% of operational carbon emissions, with residential buildings accounting for 56%. Reducing residential carbon emissions is crucial for achieving net-zero carbon goal. While many studies examine energy efficiency retrofit (EER) and electrification, few explore their long-term impacts across diverse climates an...
Various advanced control sequences for chiller plants with water-side economizers (WSE) have been proposed in literature, but the evaluation and optimization of those controls is limited. It is possible to maximize energy savings by selecting different sequences and related parameters based on the plant configuration, load, and climate. This paper...
Single-family attached houses (SFAHs) refer to residential structures that share one or more walls with neighbouring buildings, each with independent heating systems and utilities. SFAHs, also known as row houses, constitute around 50.3% of the building stock in Baltimore City, U.S., playing a crucial role in the city's building stock decarbonizati...
The adoption of onsite renewable energy generation and battery storage provides a better opportunity for building electrification and decarbonization. However, the performance of such buildings highly depends on control strategies. Priority-based control is commonly used while demand shaving control is relatively new for residential buildings. Usin...
As societies worldwide strive to reduce carbon footprints and transition toward cleaner energy sources, grid-integrated district energy systems (DES) emerge as a piv-otal player. Meanwhile, the escalating complexity of DES necessitates adaptive, synergistic, and hierarchical control of heterogeneous systems to achieve common energy and cost conserv...
This paper presents a novel model-free multi-agent Reinforcement Learning (RL) control method to enhance the resilience of community energy systems in island mode, which coordinates multiple objectives without the necessity of identifying system models that require expert knowledge. Specifically, a community-level coordinator agent is designed to a...
The future climate significantly impacts building performance and increases uncertainties in energy simulations. A rising temperature trend is expected to heighten cooling loads during summer and result in more carbon emissions. Understanding the impact of future climate on building performance is significant for policymakers to make informed decis...
Combined Heat and Power (CHP) systems utilize fuel for on-site electricity generation while recovering waste heat to provide steam for heating. To achieve computational efficiency with minimum impacts on accuracy compared to the techno-economic and physical model-ing approaches that dominate today, this study proposes, demonstrates, and evaluates a...
The urban building stock dataset consists of synthetic input and output data for the energy simulation of one million buildings. The dataset consists of four different residential types, namely: terraced, detached, semi-detached, and bungalow. Constructing this buildings dataset requires conversion, categorization, extraction, and analytical proces...
In the practice of building energy performance evaluation, two types of rating systems are widely used in building energy performance evaluation: empirical baseline energy use intensity (EUI) for existing buildings and modeled baseline EUI for new buildings. Consequently, the baseline EUIs used by those systems are inconsistent. One example is ASHR...
Although buildings are transitioning towards complex, dynamic, and interconnected systems, traditional engineering metrics that dominate today don't capture several important whole-network properties. To address this, this paper adopts ecological network analysis (ENA), which has numerous successes for natural ecosystems and socio-technical systems...
This paper presents a new open-source modeling package in the Modelica language for particle-based silica-sand thermal energy storage (TES) in heating applications, available at https://github.com/sbslab/modelica-sand. Silica sand is an abundant, low-cost, and efficient storage medium for concentrated solar power and electricity generation. Althoug...
Buildings account for 40% of global energy consumption and contribute to 30% of global carbon emissions. As energy from renewable sources increases in availability and building designers push for increased electrification, thermal energy storage (TES) systems will play a crucial role in extending the usable time horizon of renewable energy. While w...
This paper presents, to our knowledge, the first system-level engineering study to bio-mimic the cybernetics and flow dynamics of energy resources in natural ecosystems for the control of heterogeneous energy infrastructures in the built environment. To this end, we introduce a novel Biomimetic Pulsing State (BPS) control that functionally mimics m...
Although buildings are transitioning towards complex, dynamic, and interconnected systems, traditional engineering metrics that dominate today don't capture several important whole-network properties. To address this, we adopt ecological network analysis (ENA), which has numerous successes for natural ecosystems and socio-technical systems but has...
This paper presents, to our knowledge, the first system-level engineering study to bio-mimic the cybernetics and flow dynamics of energy resources in natural ecosystems for the control of heterogeneous energy infrastructures in the built environment. To this end, we introduce a novel Biomimetic Pulsing State (BPS) control that functionally mimics m...
Essential needs such as electricity generation, water distribution, and water treatment account for 12.6% of US energy consumption, of which water distribution (3.15%) is highly energy-intensive with the average energy use of 1300 kilowatt-hours per million gallons (kWh/MG). Water Distribution Networks (WDNs) are promising candidates for providing...
Ecological network analysis (ENA) combines modeling and analysis to study the structure, function, and organization of ecological food webs. Through biomimicry, ENA provides nature-inspired metrics for complex engineering systems. However, the major challenge is how to apply ENA to dynamic engineering system, such as buildings. To this end, we firs...
Retrofitting commercial buildings has great potential to reduce carbon emissions as demonstrated by previous studies in some specific cities, but their regional carbon emission reduction potential is still unknown. Thus, we develop a method to predict the long-term regional carbon emission reduction potential by retrofitting commercial buildings. S...
An efficient smart and connected community (SCC) depends on the interconnectivity of essential infrastructure systems. However, current modeling tools are unable to determine which interconnections are most important to include, particularly as system dynamics become more complex with high-order effects. To bridge this gap, we propose a com-prehens...
As climate change continues, it is expected that the risk of overheating will rise in both new and existing buildings in mixed humid climate zones in Europe. This study introduced a novel climate change sensitive sizing and design approach for cooling and heating systems in nearly zero-energy office buildings in Brussels, Belgium, for different wea...
This study assesses American Society of Heating, Refrigerating and Air-Conditioning Engineers Guideline 36 (G36) with a typical medium office building. Specifically, this study modified a Modelica model of a variable air volume (VAV) system that serves this building, which is a part of the Building Operations Testing (BOPTEST) Framework, by introdu...
Simulation-based studies of HVAC operation to mitigate indoor virus have been conducted to understand tradeoffs between indoor air quality (IAQ) and energy consumption. However, the influence of model parameter uncertainty in these studies has not been systematically quantified, which is critical when providing guidance to building operators. To ad...
This paper presents a simulation framework for evaluating building control strategies (BCSs), developed with VOLTTRON, an opensource platform that integrates data, devices, and systems for sensing and control applications, and is based on co-simulation interfaces. It realizes an integrated environment for both testing and deploying BCSs, thereby el...
Prediction of indoor airflow distribution often relies on high-fidelity, computationally intensive computational fluid dynamics (CFD) simulations. Artificial intelligence (AI) models trained by CFD data can be used for fast and accurate prediction of indoor airflow, but current methods have limitations, such as only predicting limited outputs rathe...
School buildings have a great potential for carbon emission reduction since their annual emission is about 72 million metric tons. Currently, more than 30% of school buildings were built before 1960 and are underperforming. To effectively reduce carbon emissions via school building retrofits, it is critical for policymakers to understand the carbon...
Despite the abundance of research applications of system modeling in grid-interactive efficient buildings (GEB), the transfer of those applications to real-world practices is still in its early stages. This is partially due to the lack of a summary on how system modeling should be established for a given GEB application. In this paper, we fill this...
The COVID-19 pandemic has motivated building operators to improve indoor air quality (IAQ) through long-term sustainable solutions. This paper develops a modeling capability using the Modelica Buildings library to evaluate three indoor virus mitigation strategies: use of MERV 10 or MERV 13 filtration and supply of 100% outdoor air into a building w...
Ecosystem biomimicry is a promising pathway for sustainable development. However, while typical form- and process-level biomimicry is prevalent, system-level ecosystem biomimicry remains a nascent practice in numerous engineering fields. This critical review takes an interdisciplinary approach to synthesize trends across case studies, evaluate desi...
Well-mixed zone models are often employed to compute indoor air quality and occupant exposures. While effective, a potential downside to assuming instantaneous, perfect mixing is underpredicting exposures to high intermittent concentrations within a room. When such cases are of concern, more spatially resolved models, like computational-fluid dynam...
Rapid global urbanization is a double-edged sword, heralding promises of economical prosperity and public health while also posing unique environmental and humanitarian challenges. Smart and connected communities (S&CCs) apply data-centric solutions to these problems by integrating artificial intelligence (AI) and the Internet of Things (IoT). This...
Direct evaporative coolers (DECs) are a low-energy cooling alternative to conventional air conditioning in hot-dry climates. The key component of DEC is the cooling pad, which evaporatively cools the air passing through it. While detailed numerical models of heat and mass transfer have been proposed for the cooling pad, these require many input par...
The evaluation of building energy performance requires a baseline for comparison. Common empirical baselines are usually used for existing buildings since they are fast and convenient. However, the same type of building at the same location will receive the same baseline despite their difference in usage. Individualized baselines by creating buildi...
Constant CO2 emission factors of electricity are often used to study the emissions of buildings. However, in the era of increased renewable energy for power generation, emission factors of electricity are dynamically changing. This study is to investigate the impact of dynamic CO2 emission factors, which are more realistic than constant ones, on th...
Constant CO2 emission factors of electricity are often used to study the emissions of buildings. However, in the era of increased renewable energy for power generation, emission factors of electricity are dynamically changing. This study is to investigate the impact of dynamic CO2emission factors, which are more realistic than constant ones, on the...
The WELL Building Standard (WELL) is currently one of the most comprehensive building certification programs that aim to enhance the health and well-being of building occupants. However, there is a lack of systematic evaluation of the effectiveness of WELL in achieving its goal. This study investigates the impact of WELL certification on occupant s...
Essential needs such as electricity generation, water distribution, and water treatment account for 12.6% of US energy consumption, of which water distribution (3.15%) is highly energy-intensive with the average energy use of 1300 kilowatt-hours per million gallons (kWh/MG). Water Distribution Networks (WDNs) are promising candidates for providing...
This paper presents the a set of multi-domain load models that allow simulating the dynamics of coalesced electrical power and the thermo-fluid system by exploiting the Modelica language based on the Modelica OpenIPSL power system library. This allows for phasor domain representation of the electrical grid, such as that used in de facto power syste...
Adapting building operation during the COVID-19 pandemic to improve indoor air quality (IAQ) while ensuring sustainable solutions in terms of costs and CO2 emissions is challenging and limited in literature. Our previous study investigated different HVAC operation strategies, including increased filtration using MERV 10, MERV 13, or HEPA filters, a...
As an unsupervised-learning data-driven model, Generative Adversarial Networks (GANs) have recently attracted a lot of attention for various applications. There is potential to apply GANs for large-scale building power demand prediction, which is needed for power grid operation. However, there are many GAN variations and it is unclear which GAN is...
As a popular emission reduction tool, the carbon emission trading scheme (ETS) can potentially add an economic incentive for building owners to retrofit buildings in addition to the cost savings in energy. However, the additional economic benefits of building retrofits brought by ETS has not been quantitively investigated yet. To fill this gap, thi...
In U.S. district heating (DH) systems, steam is the most common heat transport medium. Industry demand for new advanced modeling capabilities of complete steam DH systems is increasing; however, the existing models for water/steam thermodynamics are too slow for large system simulations because of computationally expensive algebraic loops that requ...
This paper introduces new models of the Modelica Buildings Library for thermo-fluid simulation of steam-based district heating systems in support of design, operation, and energy analysis. Steam represents a prominent and indispensable form of energy, providing energy for 97% of district heating and upwards of 84% for some manufacturing industries...
While equation-based object-oriented modeling language Modelica can evaluate practical energy improvements for district cooling systems, few have adopted Modelica for this type of large-scale thermo-fluid system. Further, to our best knowledge, district cooling modeling studies have yet to include hydraulics in piping networks alongside plant model...
In the United States, buildings account for 35% of total energy-related carbon dioxide emissions, making them important contributors to decarbonization. Carbon intensities in the power grid are time-varying and can fluctuate significantly within hours, so shifting building loads in response to the carbon intensities can reduce a building’s operatio...
In U.S. district heating (DH) systems, steam is the most common heat transport medium. Industry demand for new advanced modeling capabilities of complete steam DH systems is increasing; however, the existing models for water/steam thermodynamics are too slow for large system simulations because of computationally expensive algebraic loops that requ...
Power demand prediction for buildings at a large scale is required for power grid operation. The bottom-up prediction method using physics-based models is popular, but has some limitations such as a heavy workload on model creation and long computing time. Top-down methods based on data driven models are fast, but less accurate. Considering the sim...
Net-zero energy communities (NZECs) are critical to assuring the sustainability and resilience of modernized power systems. System modeling helps overcome technical challenges in designing and operating NZECs. In this paper, we present an open-source NZEC virtual testbed in Modelica based on a real NZEC in Florida, USA. This testbed consists of two...
Buildings account for approximately 36% of the United States’ total carbon emissions and building retrofits have great potential to reduce carbon emissions. Current research adopts a constant electricity emission factor although it changes over time due to the increase of renewable energy generation. To accurately predict emission reduction potenti...
The COVID-19 pandemic increased the need for buildings to protect occupants from infection due to airborne pathogens. This paper investigates the use of filtration to remove viral particles in the air handling system, specifically studying trade-offs between filter quality and operational cost. While high-efficiency filters remove viral particles m...
An artificial intelligence (AI) model trained by Computational Fluid Dynamics (CFD) simulations can be used to accelerate indoor airflow prediction. However, generating CFD data to train the AI model is time consuming. This work proposes a novel physics-informed algorithm to generate CFD training data for the AI model. The algorithm minimizes the a...
To minimize the indoor transmission of contaminants, such as the virus that can lead to COVID-19, buildings must provide the best indoor air quality possible. Improving indoor air quality can be achieved through the building’s HVAC system to decrease any concentration of indoor contaminants by dilution and/or by source removal. However, doing so ha...
District heating effectively meets the heating needs of multiple buildings while consuming less resources compared to individual heating at each building. In U.S. district heating systems, steam is the most common heat transport medium. Simulation of large steam district heating systems requires a computationally efficient and accurate steam model....
The COVID-19 pandemic has highlighted the need for strategies that mitigate the risk of aerosol disease transmission in indoor environments with different ventilation strategies. It is necessary for building operators to be able to estimate and compare the relative impacts of different mitigation strategies to determine suitable strategies for a pa...
District cooling (DC) continues to proliferate due to increasing global cooling demands and economies of scale benefits; however, most district-scale modeling has focused on heating, and to the best of our knowledge, researchers have yet to model cooling plants featuring waterside economizers in DC settings. With the popular Modelica Buildings libr...
Building retrofits have great potential to reduce CO2 emissions since buildings are responsible for 36% of emissions in the United States. Several existing studies have examined the effect of building retrofit measures on CO2 emission reduction. However, these studies oversimplified emission factors of electricity by adopting constant annual emissi...
