Session: ASME Undergraduate Student Design Expo

Paper Number: 173415

Reducing Cooling Energy & Greenhouse Gas Emissions for Houses Across the United States Through Pcm Enhanced Building Envelope and Natural Ventilation 

As more intense and prolonged heat waves have occurred across the U.S in recent years, residential buildings are facing growing challenges to maintain comfortable indoor thermal conditions while limiting cooling energy use. This study investigates the performance of phase change material (PCM)-enhanced building envelopes combined with night ventilation as a passive cooling measure for single-family houses. This study conducts a comprehensive analysis of energy savings and greenhouse gas emissions reduction potential across 16 different U.S climate zones. To evaluate the effectiveness of the proposed PCM + NV solution, four cases are simulated and compared including: (1) a baseline case with neither PCM nor natural ventilation, (2) nighttime natural ventilation (NV) only, (3) PCM-only, and (4) a combined PCM + NV solution.

The simulations are performed using EnergyPlus along with TMY weather files. The baseline is implemented based on the DOE prototype building models of single-family detached houses with a DX cooling system and a gas furnace heating system. The models for Cases 2-4 are modified based on the baseline model by adding the PCM or NV features. Parametric simulations are conducted in Cases 3 and 4 to optimize the melting point temperature of the PCM layers for all climate zones. Results show that the hybrid of PCM + NV solution can reduce annual cooling energy by between 13.2% and 70.5%, depending on the climate zone. The hybrid PCM + NV solution provides the most energy savings and emissions reduction across all climate zones compared to only-PCM or only-NV scenarios, showing the synergistic advantages of pairing passive thermal storage with natural ventilation. Moreover, this research also illustrates that the hybrid PCM + NV strategy successfully sustains safer indoor temperatures, and thus, improves thermal resilience for residential buildings.

In addition to energy savings, the study also evaluates the corresponding savings in carbon dioxide (CO₂), sulfur dioxide (SO₂), and nitrogen oxides (NOₓ) emissions resulting from lower cooling energy consumption. The studied house can save between 46.8 - 561.6 kg of CO₂, 0.000 - 0.401 kg of SO₂, and 0.042 - 1.058 kg of NOₓ. These emission savings have significant implications for enhancing public health conditions, especially for sensitive populations like the elderly, children, and those with pre-existing medical conditions who are disproportionately impacted by heat stress and air pollution. For example, in Miami (Zone 1A), a single-family house can save 561.6 kg of CO₂, 0.141 kg of SO₂, and 0.283 kg of NOₓ each year. These findings not only benefit public health, especially for susceptible populations, but also allow for PCM technology adoption to facilitate downsizing of HVAC equipment and decrease dependence on hydrofluorocarbon (HFC) refrigerants with high global warming potential. By reducing both energy consumption and high-GWP refrigerant emissions, these measures play a role in reducing the environmental impact of residential cooling. Collectively, these outcomes contribute to the development of resilient, energy-efficient, low-emission housing solutions that advance sustainable living and support long-term environmental and public health goals.

Presenting Author: Alborz Nasseri Kansas University

Presenting Author Biography: I am a rising junior at Northern Illinois University majoring in Biology with a minor in Chemistry. This summer, I am conducting research at the University of Kansas (KU) through an NSF REU program under the mentorship of Dr. Xu Han. My research focuses on reducing cooling energy use and greenhouse gas emissions in single-family houses across 16 U.S. climate zones by optimizing phase change material (PCM) and natural ventilation strategies for enhanced building envelope performance.

Authors:

Alborz Nasseri Kansas University