What do you mean by "sustainable" here? Does it imply keeping at a steady level without destroying the environment? Is it an additional meaning of "sustanable"?
In recent years, many people have joined the growing movement for sustainable development. The goal of sustainable development is to balance the needs of people with the protection of nature. For example, many architects and builders have been working to come up with new ways to construct buildings. The buildings need to be economical and safe for the health of the people who use them, but they need to be safe for the environment at the same time. Called green buildings," these environmentally friendly schools, homes, and offices are designed to save energy and water, and make use of materials that do not damage the environment. They might not seem different from regular buildings, but take a closer look!
Yes.Does it imply keeping at a steady level without destroying the environment?
Additional to what other meaning?Is it an additional meaning of "sustainable"?
able to be sustained.
■ (especially of development, agriculture, etc.) conserving an ecological balance by avoiding depletion of natural resources.
Sustainability means looking at how something impacts people, planet, and profit, the so-called "triple bottom line."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.