This technical note provides an overview of issues concerning floor heating and cooling systems including typical applications of under floor installations, the influences on floor heating and cooling output, the risk of condensation, comfort, commissioning and controls issues. Calculation of the capacity of a radiant floor heating system is given first followed by a practical example. A method to determine the output of a radiant floor cooling system is also given. This technical note complements the accompanying application handbook Floor Heating and Cooling Systems.