The answer to this question is convoluted. Sometimes it is best to use a digital outcome, while on other occasions, printing may be better. Considerations for choosing the right outcome depend on shipping, file sizes, materials used, vendors, etc. Server farms that host our online creations and data, can use up to 100 billion KwH of energy nationally ( Energy, Efficiency, & Technology).
The computers and other electronics utilized in the digital world also become an environmental and human health hazard at the end of their lifecycles. However, it is important to point out that this same problem exists in the print design world. We use large and small-scale printers, laptops, scanners, digital cameras, etc. that also end up in the landfill and exported for dangerous disassembly overseas. It's important when deciding between digital versus print to look at the entire system in which your piece will live and die.
Use our Sustainable Systems Thinking guide to help.
What does it mean for paper to be sustainable?
How can you limit printing waste? How should you select a greener printer?
What makes a better more environmentally responsible ink choice?
What constitutes a sustainable material? Where can you find them?