Yes, there are several specific topics in the Mechanical Engineering Optional Subject that require knowledge of environmental or sustainability aspects. These topics are important as they help engineers understand the impact of their designs and decisions on the environment and work towards creating more sustainable solutions. Here are some of the key topics:

1. Energy Systems and Sustainability:
- Understanding different energy sources and their environmental impact.
- Evaluating the efficiency and environmental performance of energy systems.
- Designing and optimizing energy systems for sustainability.

2. Environmental Pollution and Control:
- Studying different types of pollutants and their effects on the environment.
- Learning about various control measures and technologies to mitigate pollution.
- Designing pollution control systems and implementing sustainable practices.

3. Life Cycle Assessment (LCA):
- Assessing the environmental impact of a product throughout its entire life cycle.
- Analyzing the energy consumption, emissions, and waste generation at different stages.
- Identifying opportunities for improving the sustainability of products and processes.

4. Sustainable Materials and Manufacturing:
- Exploring eco-friendly materials and their properties.
- Understanding sustainable manufacturing processes and techniques.
- Designing products with consideration for recyclability, energy efficiency, and reduced waste.

5. Renewable Energy Systems:
- Studying various renewable energy sources such as solar, wind, hydro, and bioenergy.
- Analyzing the design, performance, and integration of renewable energy systems.
- Evaluating the economic and environmental viability of renewable energy projects.

6. Environmental Laws and Regulations:
- Familiarizing with national and international laws related to environmental protection.
- Understanding compliance requirements and environmental impact assessment procedures.
- Incorporating legal and regulatory aspects into engineering projects.

7. Green Building Design:
- Learning about sustainable building materials, energy-efficient designs, and green technologies.
- Evaluating the environmental impact and energy performance of buildings.
- Designing energy-efficient HVAC systems, lighting systems, and renewable energy integration.

Overall, the knowledge of environmental and sustainability aspects in Mechanical Engineering allows engineers to contribute towards creating a greener and more sustainable future. It helps them make informed decisions, design eco-friendly systems, and mitigate the environmental impact of their work.