A key component of the cap and trade "solution" to carbon emissions is the notion of "certified" output, i.e., the idea that a building can be certified for low carbon emissions.
Such a system -- the Leadership in Energy and Environmental Design (LEED) Green Building Rating System -- already exists, and those who want LEED certification pay to get it.
The trouble is that LEED certification is voluntary, which means that the only people to get it do so as a means of advertising their "green cred." Now what happens if LEED certification is worth money, i.e., if a LEED gold certification will allow its owner to have or sell carbon credits? Well, I would suggest that a monetized LEED will lead (pun!) to greater corruption and/or sloppier certification standards. There are over 60,000 LEED Accredited Professionals, and it only takes a few "bad apples" giving out incorrect certifications for dodgy clients before the whole system is devalued. (The same way that the credit rating agencies are now devalued.)
Bottom Line: The guardians of LEED certification need to be careful about how their system is used. When incentives go from "low-power" (voluntary) to high-power (mandatory/valuable), it's more likely that the system will be mistreated.