Energy geostructures are structure or infrastructure foundations used as heat exchangers as part of a ground source heat pump system. Although piles remain the most common type of energy geostructure, increasingly infrastructure projects are considering the use of other buried structures such as retaining walls and tunnels for heat exchange. To design and plan for construction of such systems, site investigations must provide appropriate information to derive analysis input parameters. This paper presents a review of what information regarding the ground, and also the structures themselves, would be required for the ground energy system design process. Appropriate site investigation methods for energy geostructures are reviewed, from desk study stages through in situ testing to laboratory testing of samples recovered. Available methods are described and critically appraised and guidance for practical application is given.