Saunders suggests Green Seal, a US-based non-profit that evaluates hotels, among other products, for a fee, and grants a bronze, silver or gold certification based on general sustainability.

BBC: Can hotels be truly carbon neutral?

The green property indexes are based on the analysis of over 14, 300 LEED and 18, 400 Energy Star projects that have received third-party certification based on their green achievements and performance.

FORBES: Benchmarking Green: The First Investable US Green Property Indexes for REITs

The decision to obtain that certification was based on the fact that I already knew some of it and it was fast.

WHITEHOUSE: Engage and Connect

On February 18th, they filed a court challenge to the store's card-based certification.

ECONOMIST: A labour union's pyrrhic victory