Development and Validation of Online Parameter Estimation for HVAC Systems

2003 ◽  
Vol 125 (3) ◽  
pp. 324-330 ◽  
Author(s):  
Jin Wen ◽  
Theodore F. Smith
Keyword(s):  
Energy Efficiency ◽  
Parameter Estimation ◽  
Hvac Systems ◽  
Recursive Least Squares ◽  
Volume Discharge ◽  
Thermal Loads ◽  
Variable Air Volume ◽  
Improve Energy Efficiency ◽  
System Parameters ◽  
Air Volume

Improving the energy efficiency of buildings by examining their heating, ventilating, and air-conditioning (HVAC) systems represents an opportunity. To improve energy efficiency, to increase occupant comfort, and to provide better system operation and control algorithms for these systems, online estimation of system parameters, including system thermophysical parameters and thermal loads, is desirable. Several reported studies have presented simulation results and assumed that the thermal loads are known. A difficulty in HVAC system parameter estimation is that most HVAC systems are nonlinear, have multiple and time varying parameters, and require an estimate of the thermal loads for a building zone. In this study, building zones and variable-air-volume units are modeled. The system parameters including the thermal loads are estimated using the recursive-least-squares method with a variable forgetting factor. The sensitivity of the estimation results to different factors is examined. The estimated parameters are used to predict the zone and variable-air-volume-discharge-air temperatures. Several experiments are used to validate the prediction results. The comparisons show good agreement between the experiments and the prediction results.

Development and Validation of Online Parameter Estimation for HVAC Systems

2002 ◽  
Author(s):  
Jin Wen ◽  
Theodore F. Smith
Keyword(s):  
Parameter Estimation ◽  
Thermal Load ◽  
Least Squares Method ◽  
Hvac Systems ◽  
Recursive Least Squares ◽  
Thermal Loads ◽  
Variable Air Volume ◽  
Improve Energy Efficiency ◽  
System Parameters ◽  
Occupant Comfort

Heating, ventilating, and air-conditioning systems of buildings consume nearly 50 percent of the world’s energy. To improve energy efficiency, to increase occupant comfort, and to provide better system operation and control for these systems, online estimation of system parameters, including system thermophysical parameters and thermal loads, is desirable. Several reported studies have presented simulation results and assumed that the thermal loads are known. A difficulty in HVAC system parameter estimation is that most HVAC systems are nonlinear, have multiple and time varying parameters, and require an estimate of the thermal load for a building zone. In this study, the building zone and variable-air-volume unit are modeled. The system parameters including the thermal load are estimated using the recursive-least-squares method with variable forgetting factor. The sensitivity of the estimation results to different factors is examined. Different experiments are used to validate the estimation results. The comparisons between the experiments and the estimation results show good agreement.

Development and Validation of Online Models With Parameter Estimation for a Building Zone With VAV System

2004 ◽  
Author(s):  
Jin Wen ◽  
Theodore F. Smith
Keyword(s):  
Parameter Estimation ◽  
Air Flow ◽  
Hvac Systems ◽  
Test Facility ◽  
Prediction Errors ◽  
Commercial Building ◽  
Variable Air Volume ◽  
Online System ◽  
System Models ◽  
Validation Tests

The energy consumption by building heating, ventilating, and air conditioning (HVAC) systems has evoked more attention for energy efficient HVAC control and operation. Application of advanced control and operation strategies requires robust online system models. In this research, online models with parameter estimation for a building zone with variable air volume (VAV) system, which is one of the most common HVAC systems, are developed and validated using experimental data. Building zone temperature and VAV entering air flow are modeled based on physical rules and using only the measurements that are commonly available in a commercial building. Different series of validation tests were performed in a real-building test facility to examine the prediction accuracies for system outputs. Using the online system models with parameter estimation, the prediction errors for all the validation tests are less than 0.5°F for temperature outputs, and less than 50 ft3/min for air flow outputs. The online models can be further used for local and supervisory control, as well as fault detection applications.

scholarly journals A review of common human errors in design, installation, and operation of multiple-zone VAV AHU systems

2021 ◽  
Vol 2042 (1) ◽  
pp. 012130
Author(s):  
Narges Torabi ◽  
H. Burak Gunay ◽  
William O’Brien
Keyword(s):  
Hvac Systems ◽  
Review Of The Literature ◽  
Human Errors ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air Handling Units ◽  
Occupant Comfort ◽  
Building Life Cycle ◽  
The Impact ◽  
Design Construction

Abstract Faults in air-based heating, ventilation, and air conditioning (HVAC) systems lead to energy waste and discomfort. While the emphasis of fault detection and diagnostic (FDD) research has been on hard faults in actuators, sensors, and equipment, faults arising from human errors account for a significant portion of faults occurring in HVAC systems. In this paper, human errors occurring in air handling units (AHUs) and variable air volume (VAV) thermal zones during design, construction, and operation phases are identified through a review of the literature. Then, the faults are divided into six main categories. Based on case studies investigating these faults, the impact of each fault category on occupant comfort, energy consumption, and equipment life is discussed. The authors provide recommendations to minimize human errors in AHUs and VAV zones throughout the building life cycle.

System Performance Analysis of Overlap Coupled Control Units

2001 ◽  
Author(s):  
Mingsheng Liu ◽  
Jinrong Wang
Keyword(s):  
Energy Consumption ◽  
Peak Load ◽  
Control Unit ◽  
Simulation Models ◽  
Energy Performance ◽  
Energy Simulation ◽  
Variable Air Volume ◽  
System Parameters ◽  
Air Volume ◽  
Control Units

Abstract The overlap coupled control unit is widely used in hotels, dormitory buildings, hospitals, and office buildings. Energy simulation models are developed to assess changes in energy consumption and humidity levels due to changes in various system parameters. The simulation results show that the energy consumption of the overlap unit is 3 to 5 times higher than the optimal energy consumption. To improve the energy performance, the following measures are recommended: (1) use the variable air volume technique; (2) balance total airflow based on actual peak load; and (3) replace overlap with humidistat. Quick open valves are also found to improve relative humidity control.

Improving energy efficiency of HVAC systems in buildings: a review of best practices

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Eric Kwame Simpeh ◽  
Jon-Patrick George Pillay ◽  
Ruben Ndihokubwayo ◽  
Dorothy Julian Nalumu
Keyword(s):  
Energy Efficiency ◽  
Best Practices ◽  
Energy Efficient ◽  
Low Cost ◽  
Secondary Data ◽  
Hvac Systems ◽  
Energy Usage ◽  
Content Type ◽  
Improve Energy Efficiency ◽  
Smart Technologies

PurposeHeating, ventilation and air-conditioning (HVAC) systems account for approximately half of all energy usage in the operational phase of a building's lifecycle. The disproportionate amount of energy usage in HVAC systems against other utilities within buildings has proved a huge cause for alarm, as this practice contributes significantly to global warming and climate change. This paper reviews the status and current trends of energy consumption associated with HVAC systems with the aim of interrogating energy efficiency practices for improving HVAC systems' consumption in buildings in the context of developing countries.Design/methodology/approachThe study relied predominantly on secondary data by analysing the relevant body of literature and proposing conceptual insights regarding best practices for improving the energy efficiency of HVAC systems in buildings. The systematic review of the literature (SLR) was aided by the PRISMA guiding principle. Content analysis technique was adopted to examine germane scholarly articles and finally grouped them into themes.FindingsBased on the SLR, measures for enhancing the energy efficiency of HVAC systems in buildings were classified based on economic considerations ranging from low-cost measures such as the cost of tuning the system, installing zonal control systems, adopting building integrated greenery systems and passive solar designs to major approaches such as HVAC smart technologies for energy management which have multi-year pay-back periods. Further, it was established that practices to improve energy efficiency in buildings range from integrated greening system into buildings to HVAC system which are human-centred and controlled to meet human modalities.Practical implicationsThere is a need to incorporate these energy efficiency practices into building regulations or codes so that built environment professionals would have a framework within which to design their buildings to be energy efficient. This energy efficient solution may serve as a prerequisite for newly constructed buildings.Originality/valueTo this end, the authors develop an integrated optimization conceptual framework mimicking energy efficiency options that may complement HVAC systems operations in buildings.

Directing Supervisory Control Towards Real HVAC System Integration

2011 ◽  
Author(s):  
Aaron P. Wemhoff ◽  
William Flaherty
Keyword(s):  
Energy Consumption ◽  
Supervisory Control ◽  
System Integration ◽  
Energy Savings ◽  
Hvac Systems ◽  
Control Approach ◽  
Variable Air Volume ◽  
Air Volume ◽  
Transient System ◽  
Mc Method

Heating, ventilating, and air conditioning (HVAC) systems comprise a significant portion of U. S. energy consumption. A supervisory control approach allows for the reduction of HVAC energy used. The authors previously developed and discussed the Master Controller (MC) method as a type of supervisory control that minimizes HVAC energy consumption for a given system. This paper provides two advancements towards the application of the MC method in a real system. First, airflow constraints are incorporated into the MC algorithm. Second, an approach is developed for incorporating transient system loads that are calculated via commercial software. The constrained MC method is shown to produce energy savings of approximately 40% compared to a traditional Variable Air Volume (VAV) method and VAV method with chiller control for reducing HVAC energy consumption for an example system.

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