How Are Material Advancements Shaping Energy-Efficient Cooling?

By Taha KhanReviewed by Lexie CornerOct 16 2024

This increasing demand for electricity presents a challenge: meeting cooling needs while minimizing environmental impact. Energy-efficient cooling technologies offer a sustainable solution in this context.

This article explores how these technologies contribute to sustainability and reduce environmental impact.

Overview of Traditional Cooling Methods

Traditional cooling methods, such as conventional air conditioning and refrigeration, have been extensively used in residential, commercial, and industrial settings. These systems rely heavily on mechanical compression refrigeration cycles that consume significant amounts of electricity and often use harmful refrigerants, contributing to high energy usage and environmental degradation.

Historically, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), and hydrochlorofluorocarbons (HCFCs) have been widely used in refrigeration and air conditioning. These refrigerants significantly contribute to ozone layer depletion and global warming. For example, the global warming potential (GWP) of CFC-11 is 5000, while CFC-12 has a GWP of 8500. Similarly, various HFCs and HCFCs range from 93 to 12,100 in GWP values, highlighting their contribution to global warming.²

Although these systems provide effective cooling, their energy consumption and reliance on harmful chemicals make them unsustainable in the long term. The high energy demands of these systems also strain power grids, particularly during peak summer months, leading to increased reliance on fossil fuels and a rise in greenhouse gas emissions.

Innovative Cooling Technologies

Researchers have developed several innovative cooling technologies to address the challenges associated with traditional cooling methods. These technologies aim to reduce energy consumption and minimize the environmental impact of cooling systems.

Evaporative Cooling

Evaporative cooling is a highly efficient, energy-saving method for regulating temperature. It works by utilizing water's natural ability to absorb heat through evaporation, lowering the surrounding temperature without the need for a compressor. This cooling method can be divided into air-side and water-side systems.

Air-side evaporative cooling directly cools incoming air by humidifying it, making it particularly effective in summer. In contrast, indirect evaporative cooling cools air via a heat exchanger without direct contact, ensuring better air quality control.³

Evaporative cooling is especially effective in dry climates, where humidity levels are low, making it a viable solution for regions with hot and arid conditions. Moreover, these systems do not use refrigerants like HFCs, making them environmentally friendly and contributing to reduced greenhouse gas emissions.

Advanced Refrigeration Technologies

Researchers are focusing on advanced refrigeration technologies to reduce energy consumption and environmental impact. For example, magnetocaloric refrigeration exploits the magnetocaloric effect, where materials heat up when exposed to a magnetic field and cool down when removed from it. This cyclical process maintains low temperatures without harmful refrigerants and can offer up to 30 % energy savings compared to conventional vapor compression systems.⁴

Another approach involves using natural refrigerants like ammonia, propane, and carbon dioxide (CO₂), which have much lower GWP than synthetic refrigerants like HFCs. Although natural refrigerants were widely used in the early days of refrigeration, their toxicity and flammability led to a shift toward CFCs and similar materials.

Now, with a renewed awareness of the harmful aspects of CFCs, the industry is returning to natural refrigerants as advanced technologies can effectively manage the challenges that were previously difficult to address.⁵

Novel Colling Technology Utilizing Shape Memory Alloys

In a 2024 study, researchers at the Hong Kong University of Science and Technology made significant advancements in cooling systems, focusing on groundbreaking elastocaloric refrigeration technology. They utilized shape memory alloys (SMAs) to create a solid-state cooling mechanism that is both environmentally friendly and energy-efficient.

The team developed a multi-material cascading elastocaloric device that achieved a record-breaking temperature rise of 75 K, surpassing the previous benchmark of 50.6 K. This system operates without high global warming potential refrigerants, offering a sustainable alternative to traditional cooling methods. ¹

Passive Cooling Methods

Passive cooling techniques rely on building design and natural elements to maintain comfortable indoor temperatures without mechanical cooling systems. These methods are based on principles of heat management, ventilation, and thermal mass, making them energy-efficient and environmentally sustainable.

Energy Efficiency in Buildings

In a 2022 study, researchers compared traditional cooling methods with passive cooling techniques for residential buildings in hot, arid climates. The study found that passive cooling methods, such as reflective roofs and cool-ventilated roofs, significantly reduced energy consumption.

For instance, a cool reflective roof can lower external surface temperatures by up to 20.52 °C, resulting in a 45.45 % reduction in cooling energy use. Similarly, a cool-ventilated roof reduced cooling energy demands by 66.06 %, leading to substantial CO₂ emission reductions.

The study demonstrated that passive cooling methods offer a cost-effective and energy-efficient alternative to traditional cooling, particularly in hot climates, making them highly beneficial for sustainable building design.⁶

Smart Cooling Systems

Smart cooling systems also provide energy-efficient cooling solutions. These systems utilize sensors, data analytics, artificial intelligence (AI), and energy-efficient strategies to adjust cooling levels based on occupancy and weather conditions, ensuring that energy is used only when necessary.

For instance, a 2021 study explored advancements in smart cooling systems within building operations, focusing on the integration of AI techniques to optimize heating, ventilation, and air-conditioning (HVAC) systems. The findings indicated that AI-based solutions led to average energy savings of 21.81 % to 44.36 % and comfort improvements between 21.67 % and 85.77 %.⁷

Similarly, integrating renewable energy sources, such as solar and wind power, into cooling systems has the potential to further enhance sustainability. For example, solar-powered air conditioning systems use photovoltaic panels to generate electricity, reducing reliance on grid power and decreasing the carbon footprint of cooling operations.

Conclusion: The Importance of Energy-Efficient Cooling Innovations

Traditional cooling methods, characterized by high energy consumption and environmental impact, are unsustainable in the face of climate change. Innovative cooling technologies—such as evaporative cooling, advanced refrigeration systems, passive cooling methods, and smart cooling systems—provide necessary alternatives that can reduce energy usage and greenhouse gas emissions.

These advanced technologies can meet global cooling demands while minimizing environmental footprints, contributing to a more sustainable and climate-resilient future.

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References and Further Reading

1. Zhou, G., et al. (2024) A multi-material cascade elastocaloric cooling device for large temperature lift. Nature Energy. https://doi.org/10.1038/s41560-024-01537-3
2. Swep. (n.d.). Environmental impacts of refrigerants. [Online] Swep. Available at: https://www.swep.net/refrigerant-handbook/5.-refrigerants/sd5/ (Accessed on 20 September 2024)
3. Chu, J., Huang, X. (2023). Research status and development trends of evaporative cooling air-conditioning technology in data centers. Energy and Built Environment. https://doi.org/10.1016/j.enbenv.2021.08.004
4. Office of Energy Efficiency & Renewable Energy. (n.d.). Magnetocaloric Refrigerator/Freezer. [Online] Energy.gov. Available at: https://www.energy.gov/eere/buildings/articles/magnetocaloric-refrigeratorfreezer (Accessed on 20 September 2024)
5. Sruthi Emani, M., Kumar Mandal, B. (2018). The use of natural refrigerants in refrigeration and air conditioning systems: a review. Materials Science and Engineering. https://doi.org/10.1088/1757-899X/377/1/012064
6. Athmani, W., Sriti, L., Dabaieh, M., Younsi, Z. (2023). The potential of using passive cooling roof techniques to improve thermal performance and energy efficiency of residential buildings in hot arid regions. Buildings. https://doi.org/10.3390/buildings13010021
7. Merabet, GH., et al. (2021). Intelligent building control systems for thermal comfort and energy-efficiency: A systematic review of artificial intelligence-assisted techniques. Renewable and Sustainable Energy Reviews. https://doi.org/10.1016/j.rser.2021.110969

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