Retrofitting an Existing Data Center
Although this chapter is written predominantly from the perspective of constructing an all-new Data Center, don't overlook green design and build possibilities for projects that involve upgrading your existing server environments. Although you won't be making a site selection decision, green strategies around building materials, building exteriors, and landscaping are still valid, and it's even more important to maintain good air quality around an already populated building than at a construction site.
Existing roofing systems can certainly be retrofitted with cool roofs, living roofs, or photovoltaic systems, and building commissioning can be done as easily on existing structures as on new ones.
Remember that if you retrofit a pre-existing server environment, you have already implemented one green element. You're reusing a structure rather than constructing something new and have, therefore, avoided consuming even more resources.