Xinyi Song

Georgia Tech Energy Faculty
Assistant Professor
(404) 894-7102
Research Area: 
Smart Infrastructure
Industry Area: 
Building Technologies

Xinyi Song is an assistant professor in the School of Building Construction at Georgia Tech. Her work focuses on collecting, simulating, analyzing, and representing data and information to support risk management and operation optimization in complex built environments. The goal is to promote social, economic, and environmental sustainability throughout a building’s life cycle by incorporating human factors into the decision making process. Dr. Song’s research interests include Alternative Dispute Resolution (ADR), construction safety and health, occupant’s thermal comfort uncertainty, and smart facility management.

What Brought You to Georgia Tech?
Georgia Tech’s School of Building Construction is very unique in that it has four tracks for its graduate program – from program and construction management to residential development and facility management. Not many universities in the United States have a program that spans the entire building lifecycle from beginning to end. That provides a unique advantage for researchers focused on energy efficiency because most energy consumption happens during a building’s operation and maintenance, and is affected by decisions made during the design and development phase.  The program also has a lot of support from the facility management side to help with building simulations and analysis, which we use to determine the cause of energy waste during the operations and maintenance phase and how best to address those issues.  

Discuss some of the recent work of your lab?
I am working on two projects now relating to building energy efficiency. One project is focused on hybrid ventilations systems, which have both active cooling systems, such as air conditioning or fans, as well as natural ventilation. Natural ventilation does not rely on fans to bring fresh air indoors –only opening vents, such as windows. We are looking at how hybrid ventilation systems could help save energy and actually make occupants more comfortable. In the United States, people have been reluctant to accept natural ventilation operations because they are skeptical that, particularly during hot humid months that natural ventilation would not be enough to help cool the indoor air temperature and make everyone comfortable. We rely on air conditioning to do that. But natural and hybrid ventilation is very popular in other parts of the world, especially in Europe and even more tropical climates, such as Egypt, Malaysia, and Mexico. So there is a necessity to look into the potential of using hybrid ventilation – if not natural ventilation alone. We are looking to see what the potential of using hybrid ventilation systems in the United States in different climate zones to help save energy and bring more fresh air into the indoor environment to help improve the indoor air quality and make the occupants feel more comfortable, productive and healthy.

We have another project that is focused on the mechanical cooling system, which is the heating, ventilation, and air conditioning (HVAC) system. There are two commonly used HVAC systems - Variable Refrigerant Flow (VRF) Systems and Variable Air Volume (VAV) Systems. VAV systems ae centrally controlled and are the most common HVAC system on campus. In VAV systems individual occupants don’t have control over their local spatial environment. In the best case scenario, they may have control over a thermal zone of usually two or three offices. In larger spaces, occupants really have no control over their environment. In VRF systems, each space has its own thermostat where occupants have total control over their thermal environment. We are analyzing both systems to see which is more efficient. Upfront costs of VRF systems are more expensive, but we are looking at VRF systems from a lifecycle point of view and the long-term savings potential. If we give individual occupants individual control of their thermal environment, it may result in energy savings along the way. Different occupants have different thermal preferences. Not everyone wants their thermostat set at 68°F in the summer and 75°F during winter months. A recent publication showed that females actually preferred higher temperature settings during the summer than male occupants.

We are very lucky that the Caddell Building, where the School of Building Construction is located, just went through a renovation and we are the first building on campus to have a VRF system. It will provide a great opportunity to study the impact of combined HVAC systems and occupant preferences on building energy efficiency.

Exciting new materials or processes that could curb energy consumption?
There has been 5 to 10 years of research into HVAC system efficiency alone. But until recently, the human factor has largely been overlooked. It’s becoming a very hot topic in building energy efficiency and there is a lot of research in human-building interaction going right now. We are looking a lot more at how occupants could impact energy consumption in buildings. We are trying to develop a commercial version of the Nest home automation system that automatically tracks occupant preferences. By tracking building occupant behavior patterns, we could develop something like Nest to help save energy. It’s still in the early phase of development, but we believe this will be the future direction of energy savings.  

If you weren’t teaching or conducting research, what would you be doing?
I enjoy reading a lot and traveling. I am also pregnant with my second child and have a two-year old at home, so most of the free time I have is doing things with her. It’s a really great distraction from the research world.

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