Project Overview  |  Proof of Concept  |  Final Design  |  Fabrication  |  Testing and Results  |  Meet the Team  |  Acknowledgements

Project Overview

Modern residential HVAC systems usage can be expensive. During hot summer days, air conditioning is often turned on to cool the environment. At night, the temperature typically drops below the desired indoor temperature and most people turn off their A/C and open their windows. However, the outside temperature might not drop below the desired temperature until late at night, even past midnight. To save people the troubles of getting up and opening their windows, Team 7, in partnership with The UNR Innevation Center, aims to create a Smart HVAC Economizer. The system will function based on a desired temperature range defined by the user. Thermometers located inside and outside of the building will communicate between the economizer and HVAC system to use either the A/C unit normally, or to integrate outside ambient air to heat or cool the building. The economizer system will choose the most effective way to reach the desired temperature, whether it be turning on the A/C or circulating outside air into the building. Outdoor air will flow into the building utilizing new ductwork, valves, and a fan.

The Smart HVAC economizer falls under the economizer category in the much larger HVAC industry. HVAC systems are produced worldwide, and dominated by Daikin, Gree, and Toshiba Carrier. The economizer market is set to grow at nearly 7% from 2017 to 2022, with most of this growth in the Asia Pacific region due to high demand. This economizer will be more of a local pursuit, and will focus on residential HVAC. As a team, duct layouts have been gathered to become familiar with the air distribution system, a literature search has been conducted to gather information from patents and published papers, and Jim Sacherman, the mentor, has provided funding as well as additional ideas and considerations. This Smart HVAC economizer will find its place in market due to its ability to interface with already existing HVAC systems, allowing the user use their existing system more efficiently.


Proof of Concept

The Smart HVAC Economizer system aims to demonstrate autonomous functions to reduce functioning costs of HVAC usage. By successfully integrating cloud based connections with temperature sensors and motor functions, this technology will have real world applications in the automated systems market. This project is designed to demonstrate the basic capabilities of automated economizing functions. In a larger application, this technology could be implemented to develop high amounts of savings in factory and industry environments. This technology will be able to be utilized for functions outside of temperature regulation. Fuel use regulation and light sensitive technologies would be improved with this projects technological goals.


Final design

The Smart HVAC Economizer is the fusion of both comfort and efficiency. It senses indoor and outdoor temperatures to determine the best way to meet a user-defined desired temperature. If it is possible to use free-cooling from outdoor air, similar to opening windows on a summer night, the economizer will circulate outdoor air to cool the space to the desired temperature. If not, the economizer will allow the air conditioning to function as it normally would to achieve the desired temperature. This innovation is intended to reduce the cost of operating traditional HVAC systems for residential use.

The Smart HVAC Economizer is a wi-fi connected metal valve controller that is intended to intercept existing HVAC ductwork within a residential space. In this prototype design, an Arduino Uno, Raspberry Pi Model 3 computer, and Nest Learning Thermostat work together to actively track temperature differences to drive the most efficient process of temperature regulation within that space. When the desired temperature within the space is warmer than the temperature of ambient air, the economizer autonomously opens a valve that connects ambient air to the HVAC ductwork and activates a fan to circulate air within the space. The system will redirect air flow to its original path once the desired temperature is achieved, or the conditions are not favorable to use outdoor air to achieve the desired temperature. Air filters and weather stripping are used in this prototype design to ensure well insulated and safe operation of the HVAC system. For ease of use, an installation and safety guide is provided with the Smart HVAC Economizer.

This project is intended to reduce the cost of operating traditional HVAC systems for residential use across America. The system is intended to drastically reduce the amount of air-conditioning energy expenses people incur while simultaneously investigating alternatives to energy usage in the high energy demanding world of today.




The Smart HVAC Economizer system consists of parts that have either been purchased from a seller or modified parts to be machined by Team 7. The structure of the system will be comprised of steel sheet metal that will be cut by a CNC machine and assembled with nuts and bolts. The final structure will be similar to a box shape, with walls that swing inwards to divert the air. Holes located on the sheet metal will be created using a hand drill and clamps to hold the metal in place. Two sheets of metal will be used as doors that will be attached to the based of the system with basic door hinges. Basic DC motors will be attached to the rotating axis of both doors to allow them to open and close depending on where the air flow will be.

The assembly of the system will mainly consist of manually fastening all nuts and bolts required for this prototype into holes in the sheet metal. The Arduino Uno and Raspberry Pi Model 3 will be wired by hand, as will the power systems for the motors. Once the metal sheets have been machined properly and assembled, weather stripping will be used to line any cracks in the system to prevent unintended leakage.

The code that the system will run off will be created in the Artik platform, which will allow the Nest thermostat to communicate with the rest of the system. The code will activate different relays depending on the temperature situation in order to power the correct motor to open the valve. The code will also trigger the home’s central fan to turn on and circulate the air more quickly, if the situation is favorable for free cooling.


Testing and Results

The Smart HVAC Economizer performed functions that were specified in early design phases. The main goal of this design was to ensure that the economizer doors would open and close correctly due to the cases the economizer would encounter during operation. The prototype design of the Smart HVAC Economizer was tested by creating different environments for temperature sensors to encounter. Simulated “House” and “Ambient Air” temperature environments were manipulated to either open or close the doors of the economizer depending on if the economizer was in the on or off position. Testing was carried out over a 48 hour window until code and mechanical subsystems met the design specification standards. The system successfully reacted to temperature differences and  the economizer operated autonomously as intended.

Testing was carried out all through the assembly of the prototype. Before each subsystem was integrated, it required testing to make sure it functioned independently, then required further testing as part of the whole system. The product was tested approximately 60 times as individual and system units.

As this is a prototype design, the system, although meeting specifications, has room for improvement. One area of improvement within the system is the motor controlled door system. The motor-line connected operation system proved to be an inconsistent way to open and close the doors. Multiple iterations of the motor-wire door motion systems were tested to find the most consistent results to this problem. Although the system improved with iterations, the prototype still required troubleshooting during testing and did not have an intuitive design.

On Innovation Day, the team experienced failures due to batteries dying, and motor system components not being fully secured. In order to fix this, the team acquired additional batteries, soldered them, and replaced the old ones. The team continuously reattached the motors and attempted to secure them with tape and glue.

This product solves two major problems that consumers face today. Users benefit from this system by saving on energy expenses during warm seasons. The technology implemented in this design also aims to reduce emissions by giving people an alternative to traditional air-conditioning systems. The Smart HVAC Economizer will pave the way for cleaner energy alternatives in the HVAC market. The system was well received during the University of Nevada, Reno’s 2018 Innovation Day, and multiple investors have approached the team to further investigate the possibilities of this system.


Meet the Team


Aaron Do is a fourth year Mechanical Engineering student at the University of Nevada, Reno. Originally from the Bay Area, Aaron hopes to use his Bachelor’s degree to apply knowledge and positively impact the community. As an Undergraduate Research Assistant,  Aaron works closely with the University to develop new solutions to societal issues. After Graduation in December 2018, Aaron hopes to pursue a career as a design engineer.




Megan Higley is a third year Mechanical Engineering student at the University of Nevada, Reno. She was born and raised in Reno, Nevada. Megan hopes to officially enroll in the Accelerated Master’s program this January to pursue her Master’s in Mechanical Engineering and obtain a Certificate in Nuclear Packaging. In the future, she hopes to work with the national labs and learn more about used nuclear fuel reprocessing. She is on track to graduate with her bachelor’s in December 2018. Throughout her time spent at UNR, she has developed more programming skills, like ANSYS Fluent, Solidworks, and Matlab. Her most difficult project has been research in fuel cladding temperatures within fuel casks, where she has learned to use ANSYS and high performance computing techniques.




Daniel Vong is a third year Mechanical Engineering student at UNR. He was born and raised in Reno. Daniel is currently working towards his Bachelor’s degree. During his time at UNR, Daniel has worked on many projects, one of which includes researching heat transfer in pipe flow through computer simulations. From that project, Daniel learned how to use the basics of Nek5000 and Linux operating systems. At his time at UNR, Daniel has learned how to use SolidWorks, Matlab, and Nek5000. Daniel is considering to pursue a Master’s degree after graduating with his Bachelor’s degree in December 2018.




Carly Farthing is a fourth year Mechanical Engineering student. Born and raised in Reno, Nevada, she decided to attend Hawaii Pacific University in Oahu, Hawaii to further pursue her golfing career. After two years, she transferred to UNR to more seriously develop her engineering knowledge. She plans on interning with multiple engineering firms in the area next semester, with the goal of working with companies that focus on environmentally positive projects.





Austin Vial is a fourth year Mechanical Engineering student at UNR with a minor in Mathematics. Austin was born and raised in Reno, NV throughout high school, later attending California Lutheran University where he played football for two years, ultimately leading to his decision to transfer to UNR to continue his studying in the field of engineering after graduating Spring of 2018. Along with learning AutoCAD first hand during his civil engineering internship, he also has acquired the skills of FEA analysis in SolidWorks Austin has shown great interest in attending the masters program for Mechanical Engineering specifically at UNR, though he will apply to an array of differing programs as well.