Green building councils, and the rating tools they operate, exist largely to provide clear market signals to consumers, industry and the government on green building claims. The relationship between green building councils, the rating tools, and the market is built on trust with the market depending that the information provided by green building councils, and their rating tools, is accurate and unbiased. This research reviews recent publications by the New Zealand Green Building Council (NZGBC) to determine the claims that have been put forward to the market in relation to Homestar (version 4). A case study, cost comparative analysis is then undertaken to determine the ability of residential dwellings to achieve these claims. The study finds that the NZGBC is presenting conflicting information to the market, further determining that whilst it is possible for Homestar to deliver operational savings, many dwellings may fall short of the NZGBC's claims.