This European Standard specifies the terms and definitions, test conditions, test procedures and requirements for the rating and performance of direct exchange-to-water ground coupled heat pumps with electrically driven compressors, used for space heating and/or cooling. Brine can be used instead of water. This European Standard applies to factory-made units with horizontal in-ground collectors. In the case of units consisting of several parts, this standard applies only to those designed and supplied as a complete package. Water-to-direct exchange and direct-exchange-to-direct exchange ground coupled heat pumps are covered by EN 15879-2. Direct exchange-to-air ground coupled heat pumps and air-to-direct exchange heat pumps are covered by EN 15879-3. This European Standard does not apply to units using transcritical cycles, e.g. with CO2 as refrigerant.