Net Zero Energy House Evaluation

A net zero energy home was designed and built by Purdue University for the 2011 Solar Decathlon in Washington, DC. After earning a 2nd place finish in this international competition, the home was permanently located in Lafayette, IN and became a private residence.  Since that time, energy monitoring equipment has measured both energy consumption of the home and energy generation by the solar photovoltaic panels. Three full years of data (2013 to 2015) have been collected to show that the home has met its original design goal for net zero energy.  Beyond net zero, the data also shows interesting seasonal trends for HVAC, water heating, lighting, and other energy consuming devices. A survey of the current occupants provides further insight into how well features like indoor air quality, comfort, and aesthetics were incorporated into the overall design. The results suggest that a net zero energy home can be accomplished without sacrificing quality of life

An Interdisciplinary Solar Energy Project

An HVAC course, previously offered to students in Mechanical Engineering Technology (MET), has been re-structured to include students in Building Construction Management (BCM). A large project is always an integral part of this course, creating a unique opportunity for collaboration between two distinctly different groups of Technology students. This cooperation is particularly beneficial because MET and BCM graduates frequently cross paths during their professional careers. Many MET graduates operate and service heating, ventilating, and air conditioning equipment that was originally specified and installed by BCM graduates. This paper discusses and evaluates student interactions during a solar energy renovation project that was completed in the Spring of 1996

Optimization and Evaluation of a Botanical Air Filtration System in a Residence

Poor Indoor Air Quality (IAQ) can significantly influence a person’s health, comfort, and productivity. Studies by the U.S. Environmental Protection Agency (EPA) indicate that Americans, on average, spend over 90 percent of their time indoors where the air may be two to five times more polluted than outdoors. Comparative risk studies performed by the EPA and the Science Advisory Board (SAB) rank indoor air pollution among the top five environmental risks to public health. Studies have shown that plants are effective in removing indoor air contaminants as they break down air contaminants into their fundamental elements, and through the process of photosynthesis, plants can absorb carbon dioxide from the indoor air. The Biowall is a botanical air filter which is designed to purify indoor air and improve IAQ through plant-assisted phytoremediation. Considering the development of high-performance building technology, the best solution may be to integrate plants into heating, ventilating and air conditioning (HVAC) systems. Using plants can reduce the energy consumption by decreasing the ventilation requirements. In addition, it also can provide moisture in the air, which can reduce the loads on the cooling equipment while delivering comfortable air quality. Earlier analyses for the Biowall showed it has the potential to remove contaminants and improve air quality. However, they were completed either in an environmental chamber or in another controlled environment and the Biowall was not connected with the HVAC system. As of yet, little research has been conducted on the performance of the Biowall in a residential setting. This paper evaluates the performance of the Biowall in a home, evaluates the control algorithms, and provides recommendations for long-term Biowall management. The Biowall system was installed in a research residence called the ReNEWW House, which is a living laboratory and located in West Lafayette, IN. During the summer of 2016, a prototype Biowall was settled in the ReNEWW House. This paper evaluates the control strategies of the irrigation and fan system, present a thermodynamic model of the Biowall, and share results of the performance of the Biowall in terms of IAQ. The results suggest that the IAQ of the ReNEWW House was maintained well by the Biowall

Demand Controlled Heat Recovery for Residential Applications

Heating and cooling for residential buildings consumes a lot of energy in the United States every year, which leads to Energy Recovery Ventilator (ERV) systems becoming more common for residential applications. An ERV is a relatively simple air to air heat exchanger with supply and exhaust fans. The supply fan pulls outdoor air into the house while the exhaust fan pulls stale air from the house. The ERV preheats outside air during cold weather and cools/dehumidifies outside air during warm weather. These systems are a good investment because they typically achieve a simple payback of 2 years or less based on energy savings.  ERV’s also have an important role for Indoor Air Quality (IAQ) in modern energy efficient homes that are carefully sealed to minimize the infiltration. One challenge is determining an optimal strategy for when to turn on the fans for the ERV. Unnecessary run time wastes energy by running equipment when it is not necessarily needed for IAQ. This paper explores a demand controlled ventilation strategy that has been deployed in a net zero energy home which was designed and built by Purdue University for the 2011 Solar Decathlon. The control strategy only runs the ERV when direct measurements for IAQ indicate that fresh outside air is needed. CO2, VOC, and relative humidity levels are monitored in the home on a continuous basis. When any of these measurements rise above a specified threshold, the heat recovery system turns on and continues to run until the IAQ levels return to healthy levels. This paper summarizes the results of several years of demand controlled ERV performance in terms of IAQ and energy savings. The results clearly show that this optimized control strategy should be considered in more ERV installations

Remotely Accessible Solar Energy Laboratory for High School Students

A remotely accessible solar energy laboratory has been developed for real-time experimentation using solar heating and photovoltaic equipment that is physically located at Purdue University. Indiana high school students are the first customers for this on-line resource. In addition to sensor data, the web-based laboratory includes lesson plans, tutorials, assessment questions, and a feedback utility. This project is helping science teachers meet new state science standards from the Indiana Department of Education, which call for hands-on laboratory activities and real time data analysis. Remotely accessed labs are becoming popular because they offer the opportunity for large numbers of students to learn from state-of-the-art equipment. The cost of expensive laboratory equipment is easier to justify if it can be widely used

International Partnership Using Remotely Accessed Labs

An international project between the Mechanical Engineering Technology Department at Purdue University and the HVAC Engineering Department at HTA Lucerne (Switzerland) is testing the limits of the remote access concept by creating a laboratory network that is separated by thousands of miles. Using web-enabled HVAC equipment, U.S. students are determining the performance and return on investment for a heat recovery system that is physically located in Switzerland. The converse is also true, Swiss students have access to a variety of equipment located in the U.S. This remote access project is a good example of a sustainable partnership that adds an international perspective to undergraduate education. Although a relatively small number of students have visited the other institution in person, larger numbers of U.S./Swiss students are recognizing the globalization of engineering practice during routine laboratory work

Field Evaluation of Solar Thermal Air Collectors

This paper documents the performance of three different active flat plate solar thermal air collectors that were designed, built, and installed on the roof of a university building. The three collectors circulate air and use small fans for capturing and delivering supplemental heat for the building. These collectors are part of a larger solar energy installation used in a university setting for teaching and research about renewable energy. Each collector has a different configuration to illustrate how a solar collector’s design impacts its ability to capture thermal energy. A web-based building automation system provides real time data on solar collector performance that can be used by students and researchers. The three new collectors achieved 20% to 25% energy conversion efficiency when analyzed according to ASHRAE Standard 93 “Methods Of Testing To Determine The Thermal Performance Of Solar Collectors”. Testing also showed that the amount of air flowing through the collectors had a significant impact on overall performance. The solar collectors also achieved an energy factor (the ratio of heat collected to fan power) of approximately 5, effectively demonstrating the viability of solar thermal technologies

Environmental Index for Real Time Feedback on Biowall Indoor Air Quality

This paper describes an ongoing field evaluation of a simplified Environmental Index (EI) that provides a homeowner with an intuitive metric for assessing indoor air quality based on regular measurements of temperature, humidity, and Volatile Organic Compounds (VOC’s). These discrete measurements are used to compute an overall weighted score that correlates with the comfort and health of the living space. Although this environmental index is not a rigorous scientific computation, it is an initial point to improve residents’ understanding of Indoor Air Quality (IAQ) by providing active feedback. The context of this environmental index work is the Biowall, a living wall of plants that is integrated into the central air conditioning system of a home to improve IAQ. The environmental index is an opportunity to begin providing a homeowner with real time feedback on comfort, health, and the performance of the Biowall. A simplified graphic user interface was designed using User Experience (UX) principles to provide a graphical presentation of an environmental index score that is easy to interpret and act upon. As expected, the environmental index fluctuates based on occupancy and activities in the space, such as cooking or cleaning. It was found that VOC levels fluctuated the most and thus had the most significant impact on the Environmental Index

Applying User Experience (UX) Principles to Net Zero Energy Buildings

As buildings have become more complex, interpreting building performance becomes challenging. A Building Automation System (BAS) has hundreds of data points that monitor performance but the data is frequently under-utilized. Over 20% of a building’s energy is wasted through energy inefficiencies that go undetected. Building controls are not going to get easier, but methods are being developed to simplify monitoring building performance. An Energy Dashboard is a graphic interface for a BAS that simplifies the monitoring and control of a building. An energy dashboard automatically tracks building energy use to help detect overconsumption patterns or malfunctioning equipment. Energy dashboards allow for building occupants to monitor energy usage easily in real-time, an effective way to engage occupant behavior changes. This study designed and evaluated a prototype energy dashboard that demonstrates how to monitor net zero energy commercial buildings of the future. The energy dashboard compared energy consumption and generation patterns for a variety of building systems and solar energy equipment in an HVAC laboratory. The energy dashboard was evaluated by university students with a background in HVAC to gather feedback and improve the energy dashboard’s diagnostic abilities. The result is an easy to deploy graphic interface that can help building professionals interpret and improve performance of complex buildings. The students were also asked questions to rank importance of performance indicators based off a previously done study. An analysis was done to determine where students aligned with building professionals. This study improved on current key performance indicators and how to simplify building performance metrics