Which factor is essential in design decisions regarding environmental issues?

Minimizing waste materials is crucial in design decisions concerning environmental issues as it directly impacts sustainability. Effective design seeks to reduce the volume of waste generated during the production process and after the product's life cycle has ended. This principle aligns with environmental goals such as reducing landfill usage, conserving resources, and limiting pollution.

By focusing on minimizing waste, designers can implement practices such as using efficient manufacturing techniques, selecting materials that can be recycled or reused, and ensuring that products have a longer lifespan. This approach helps to conserve natural resources and decreases the overall environmental footprint of products, making it a key consideration in modern engineering practices.

Other options such as using more energy, creating non-repairable products, and choosing expensive materials do not contribute positively to environmental sustainability. In fact, they may have detrimental effects, emphasizing the importance of minimizing waste as a core strategy in environmentally responsible design.