A review is presented of cooling systems used in underground railways. Current cooling methods and potential advantages of using heat storage are presented. The analytical tools available to the engineer in assessing thermal capacitance and heat storage are discussed and the possibilities for improvements in the investigation of heat loads in underground railways are examined. This paper also assesses the most appropriate methodology for modelling low-energy cooling systems, with reference to their inclusion in the complex environment of an underground railway. (c) 2005 Elsevier Ltd. All rights reserved.