Abstract
A commercially available calorimeter has been used to investigate the specific heat of a high-quality KNaFeAssingle crystal. The addenda heat capacity of the calorimeter is determined in the temperature range . The data of the KNaFeAs crystal imply the presence of a large contribution to the specific heat which gives evidence of -wave order parameter symmetry in the superconducting state. To improve the measurements, a novel design for a calorimeter with a paramagnetic temperature sensor is presented. It promises a temperature resolution of and an addenda heat capacity less than at .