This paper reviews the existing literature on environmental performance indicators as they relate to private sector organisations, followed by a basic classification of ways in which environmental data are being standardised for use in indicators. It was found that the majority of standardisation schemes for environmental information fall into one of five categories, namely standardised using economic criteria, physical impact categories (such as global warming potential), linear programming methods (such as productive efficiency), economic valuation methods or as part of business management review processes. The paper concludes that environmental data, once normalised, should be used in a diversity of indicators that are tailored to the information needs of the data users and that, as long as normalisation of data is kept separate from aggregation and standardisation, many different indicators can be developed based on a comparatively small dataset.