HVAC System Analysis and Energy Audit: The Providence Athenaeum

To evaluate the impact of potential modifications to the HVAC system the Historical Value Adding Consultants developed a building energy model. The building energy model was constructed using a Microsoft Excel spreadsheet that utilizes typical meteorological year (TMY) data to determine the average energy usage of the Athenaeum for a typical year. The model has been validated against actual energy usage and is used to identify and quantify energy savings resulting from design alternatives

Dynamic modeling, intelligent control and diagnostics of hot water heating systems

Heating, ventilating and air-conditioning (HVAC) systems have been extensively used to provide desired indoor environment in buildings. It is well acknowledged that 25-35% of the total energy use is consumed by buildings, and space heating systems account for 50-60% of the building energy consumption. Furthermore, roughly half of the energy consumed goes to operation of heating systems. In the past few years the energy use has shown rapid growth. Therefore, it is necessary to design and operate HVAC systems to reduce energy consumption and improve occupant comfort. To improve energy efficiency, HVAC systems should be optimally controlled and operated. This study focuses on developing advanced control strategies and fault tolerant control (FTC) using information from fault detection and diagnosis (FDD) for hot water heating (HWH) systems. To begin with, HWH system dynamic models are developed based on mass, momentum and energy balance principles. Then, embedded intelligent control strategies: fuzzy logic control and fuzzy logic adaptive control are designed for the overall system to achieve better performance and energy efficiency. Moreover, in designing the advanced control strategies, the parameter uncertainty and noise from measurement and process are taken into account. The extended Kalman filter (EKF) technique is utilized to handle system uncertainty and measurement noise, and to improve system control performance. After that, a supervisory control strategy for the HWH system is designed and simulated to achieve optimal operation. Finally, model-based FDD methods were developed by using fuzzy logic to detect and isolate measurement and process faults occurring in HWH systems. The FDD information was employed to design model-based FTC systems for various faults and to extend the operating range under failure situations. The contributions of this study include the development of a large scale dynamic model of a HWH system for a high-rise building; design of fuzzy logic adaptive control strategies to improve energy efficiency of heating systems and design of model-based FTC systems by using FDD information

Development of a Night Vision Goggle Heads Up Display For Paratrooper Guidance

This thesis provides the proof of concept for the development and implementation of a Global Positioning System (GPS) display via Night Vision Goggles (NVG) Heads-Up Display (HUD) for paratroopers. The system has been designed for soldiers who will be able to utilize the technology in the form of a processing system worn in an ammo pouch and displayed via NVG HUD as a tunnel in the sky. The tunnel in the sky display design is essentially a series of boxes displayed within the goggle\u27s HUD leading the paratrooper to the desired Landing Zone (LZ). The algorithm developed receives GPS and inertial sensor data (both position and attitude), and displays the guidance information in the paratrooper\u27s NVG HUD as the tunnel in the sky. The primary goal of the project is to provide a product which allows military personnel to reach a desired LZ in obscured visibility conditions such as darkness, clouds, smoke, and other unforeseen situations. This allows missions to be carried out around the clock, even in adverse visibility conditions which would normally halt operations

Solar Powered Atmospheric Water Generation

Several atmospheric water generation (AWG) system configurations were analyzed to determine the feasibility of AWG as a method to combat water stress. In order to best combat water stress, AWG must be implemented in such a way which minimizes the energetic and monetary cost of water production. Thermodynamic and economic analyses were used to compare the performance of several AWG system configurations. Metrics such as specific energy consumption (SEC) and levelized cost of water (LCOW), which measure the energetic and monetary cost of water production respectively, were used to compare each system. Using this approach, the optimal system configuration was found to be a batch-style desiccant-based AWG system which utilizes latent energy recovery. The minimum theoretical SEC and LCOW for this system are 210 kWh/m3 and 3.34 $/m3 (12.64$/Kgal). A prototype of a batch-style desiccant-based AWG system with no energy recovery was developed and tested. The evaluation of this system validated the approach used in the thermodynamic analyses for predicting the system’s performance. Future work will involve implementing latent energy recovery and redesigning some of the system components in order to further decrease the system’s SEC

Advancing Embedded and Extrinsic Solutions for Optimal Control and Efficiency of Energy Systems in Buildings

Buildings account for approximately 40% of all U.S. energy usage and carbon emissions. Reducing energy usage and improving efficiency in buildings has the potential for significant environmental and economic impacts. To do so, reoccurring identification of hardware and operational opportunities is needed to maintain building efficiency. Additionally, the development of controls that continually operate building systems and equipment at energy optimal conditions is required. This dissertation provides contributions to both of the aforementioned areas, which can be divided into two distinct portions. The first presents the framework for the development of an automated energy audit process, termed Autonomous Robotic Assessments of Energy (AuRAE). The automation of energy audits would decrease the cost of audits to customers, reduce the time auditors need to invest in an audit, and provide repeatable audit processes with enhanced data collection. In this framework of AuRAE, novel, audit-centric navigational strategies are presented that enable the complete exploration of a previously unknown space in a building while identifying and navigating to objects of interest in real-time as well as navigation around external building perimeters. Simulations of the navigational strategies show success in a variety of building layouts and size of objects of interest. Additionally, prototypes of robotic audit capabilities are demonstrated in the form of a lighting identification and analysis package on a ground vehicle and an environmental baseline measurement package on an aerial vehicle. The second portion presents the development and simulation of two advanced economic building energy controllers: one utilizes steady-state relationships for optimizing control setpoints while the other is an economic MPC method using dynamic models to optimize the same control setpoints. Both control methods balance the minimization of utility cost from energy usage with the cost of lost productivity due to occupant discomfort, differing from standard building optimal control that generally addresses occupant comfort through setpoint limits or comfort measure constraints. This is accomplished through the development of component-level economic objective functions for each subsystem in the modeled building. The results show that utility cost and the cost of occupant productivity from optimal comfort can be successfully balanced, and even improved over current control methods. The relative magnitude of the cost of lost productivity is shown to be significantly higher than the cost of utilities, suggesting that building operators, technicians, and researchers should make maintaining occupant comfort a top priority to achieve the greatest economic savings. Furthermore, the results demonstrate that by using steady-state predictions, the majority of the performance gains produced with a fully dynamic MPC solution can be recovered

Predicting Occupied Zone Temperature Using Simplified Modeling Methods

Due to the expected level of thermal stratification that is present in buildings which are subject to high levels of infiltration during the heating season, the well mixed modeling approach may not be an appropriate method for modeling interior conditions in structures with inefficiently constructed envelopes. A simplified modeling method known as the Three-Node Displacement Ventilation RoomAir Model was developed by da Graça (2003) for predicting levels of thermal stratification present in buildings utilizing displacement ventilation systems (DV). This paper examines the level of thermal stratification in a building with no forced air that is subject to high levels of infiltration during the heating season, and the ability of the Three-Node Displacement Ventilation RoomAir Model to accurately model the thermal stratification therein. It was found that the levels of thermal stratification in the test building were such that the well mixed modeling approach is not appropriate. However, the Three-Node Displacement Ventilation RoomAir Model was also found to be unsuitable for modeling the conditions set forth in this research due to the methods for predicting temperature distribution utilized in the model. It was concluded that another method for modeling thermal stratification in loosely constructed buildings during the heating season should be developed

Determining Key Parameters and Guidelines for the Design of an Electrically Activated Concrete Slab for Peak Shifting in a Light-Weight Residential Building in a Northern Climate

A thermal storage system for residential buildings in a Northern climate is developed for electrical peak shifting and shaving. To facilitate implementation, only commercially available products are used for the system in conjunction with common construction methods. A thermal model is created with the TRNSYS simulation software and validated using data from a two-year monitoring campaign. The thermal model is used to identify key system parameters and propose system design guidelines. It is determined that, for residential buildings with a footprint varying between 80 m2 to 200 m2, the basement floor slab can be used for thermal storage with electrical heating cables and that the entire basement heating load can, during the peaks, be shifted to off peak periods. The optimal assembly for the basement floor is composed of 102 mm of extruded polystyrene insulation followed by 152 mm of concrete. The electric heating cables are positioned at the bottom of the concrete layer. This assembly can be controlled with the air set point temperature. The air setpoint temperature of basement rooms during charging needs to be 2 degC higher than the air setpoint temperature during normal operating conditions. The required charging time for building footprints of 80, 120 160 and 200 m2 corresponds to 6.00, 5.51, 5.05 and 4.66 hours, respectively

Development of an adaptive fuzzy logic controller for HVAC system

An adaptive approach to control a cooling coil chilled water valve operation, called adaptive fuzzy logic control (AFLC), is developed and validated in this study. The AFLC calculates the error between the supply air temperature and supply air temperature set point for air in an air handling unit (AHU) of a heating, ventilating, and air conditioning (HVAC) system and determines optimal fuzzy rule matrix to minimize the hydronic energy consumption while maintaining occupant comfort. The AFLC uses genetic algorithms and evolutionary strategies to determine the fuzzy rule matrix and fuzzy membership functions for an AHU in HVAC systems;Cooling coil models are developed using neural network, general regression neural network and lump capacitance methods to predict the supply air temperature. These models helped with the development of the adaptive fuzzy logic controller;Two types of validation experiments were conducted, one with cyclically changing supply air temperatures and the second with cyclically changing supply air flow rates. Experiments conducted on two identical real HVAC systems were used to compare the performances of the AFLC to a conventional proportional, integral and derivative (PID) controller. To remove bias between the testing systems, the controllers were switched from one system to the other;The validation experiments indicate that the HVAC system operated under the AFLC consumes 1 to 7 % less hydronic energy when compared with a conventional PID controlled system. More actuator travel distance was observed when using the AFLC. The AFLC maintained better occupant comfort conditions when compared with the conventional PID controller. It was observed that the controlled variable for the AFLC system required 0 to 185% more rise time, had 9 to 68% less overshoot and required 11 to 45% less settling time as compared to the conventional PID controlled system

Universal design of an automatic page-turner

This thesis deals with the effectiveness of automatic page-turners as one form of assistive technology. It examines several of the existing commercially available products with a view to developing a universal system that would have the potential to satisfy both the special needs and musician sectors. It explores the current trends regarding the collection of statistical data on people with a physical disability, which is intended to identify the= present and future needs for such assistive technology devices. The project utilizes a usercentric approach to document the requirements of the end users of such a device, before conceptualising a model which would have the potential to satisfy the expanded target market. It explains in detail the development process of the working model, which employs two anthropomorphic finger-like mechanisms, both of which incorporate force feedback. These finger-mimetic components are used to separate and turn the pages of the reading material. A functional prototype was built and a report of the preliminary testing carried out, together with a fully documented illustration of the final working engineering model is included. The test results reveal that the system has shown great potential for the successful development of a more universal Automatic page turner that could satisfy both identified markets

Retrofitting a high-rise residential building to reduce energy use by a factor of 10

This thesis details the ways in which energy is consumed in an existing Canadian high-rise apartment building and outlines a strategy to reduce its consumption of grid purchased energy by 90%. Grid purchased energy is targeted because the building is located in Saskatchewan where energy is predominantly generated from fossil fuels that release greenhouse gas emissions into the environment. Greenhouse gas emissions are targeted because of the growing consensus that human activities are the cause of recent global climate destabilization and the general trend towards global warming. Energy consumption is also a concern because of anticipated resource shortages resulting from increases in both global population and average per capita consumption. Many researchers are beginning to claim that a factor 10 reduction in energy use by industrialized nations will be required in order for our civilization to be sustainable.The building that was studied is an 11 story seniors high-rise with a total above ground floor area of 8,351 m2. It was constructed in 1985, in Saskatoon, SK, and it is an average user of energy for this region of the world and for a building of its size and type. Numerous field measurements were taken in the building, both during this study and previously by the Saskatchewan Research Council. These measurements were used to create a computer model of the building using EE4. After the computer model of the building was created different energy saving retrofits were simulated and compared. Over 40 retrofits are presented and together they reduce the annual grid purchased energy of the building from 360 kWh/m2 (based on above ground floor area) to 36 kWh/m2, a factor 10 reduction. Natural gas consumption was reduced by approximately 94% and grid purchased electrical consumption was reduced by approximately 81%. As a result of these energy savings, a factor 6.6 reduction (85%) in greenhouse gas emissions was also achieved. The goal of factor 10 could not be achieved only through energy conservation and the final design includes two solar water heating systems and grid-connected photovoltaic panels. These systems were modeled using RETScreen project analysis tools.Capital cost estimates and simple payback periods for each retrofit are also presented. The total cost to retrofit the building is estimated to be $3,123,000 and the resulting utility savings from the retrofits are approximately$150,000 per year. This is a factor 6.0 reduction (83%) in annual utility costs in comparison to the base building. While the typical response to proposing a “green” building is that financial sacrifices are required, there is also research available stating that operating in a more sustainable manner is economically advantageous. This research project adds to the “green building economics” debate by detailing savings and costs for each retrofit and ranking each retrofit that was proposed. The most economically advantageous mechanical system that was added to the building was energy recovery in the outdoor ventilation air. It should also be noted that there was already a glycol run-around heat recovery system in the building and even greater savings would have been obtained from installing the energy recovery system had this not been the case.While the goal of factor 10 required economically unjustifiable retrofits to be proposed, the majority of the retrofits had simple payback periods of less than 20 years (30 out of 49). This research shows that certain retrofits have highly desirable rates of return and that when making decisions regarding investing in auditing a building, improving energy efficiency, promoting conservation, or utilizing renewable energy technologies, maintaining the status quo may be economically detrimental. This would be especially true in the case of new building construction