"At its heart," says CEO Colin Dyer in JLL's sustainability report, "sustainability at JLL is about maintaining and expanding our role as a good corporate citizen. ... We develop real estate services that anticipate and address our clients' needs while creating positive change in our industry. Together, these will ensure that JLL remains a sustainable enterprise that clients, employees, investors, and other stakeholders can rely on for the long term." In effect, this statement adds another dimension to the definition of sustainability as we've used it in the case. It reflects the so-called "triple-bottom-line" approach to sustainability accounting. According to the American Institute of Certified Public Accountants, the triple bottom line consists of: "1) economic viability, 2) social responsibility, and 3) environmental responsibility." If we adopt the triple-bottom-line approach, what does sustainability cover in addition to environmental resources? In other words, what else do companies intend to sustain? Explain how and why the added dimension of sustainability is consistent with the dimension of environmental responsibility.