Measurements were carried out of air velocity, temperature and lumber moisture content on five cross circulation drying tunnels with heat recovery equipment at Swedish saw mills, and the power consumption of the blower motors was determined. The measurements were completed by the evaluation of works' records, giving data of water removal and energy consumption. The mean air velocity along height of stack showed variations between 0,35 and 1,69 m/s for different tunnels and piling properties and the velocity distribution was of different character. With regard to the quality of export lumber (discolouration, resin flow) a maximum dry bulb temperature of 50°C was not exceeded and the wet bulb temperature was not higher than 35°C at the initial stage of drying. At these temperatures there may arise stains caused by fungi, the kiln operation thus must be balanced between jungi and cracks. In one plant a drying schedule was worked out on this basis.-This final mean moisture content varied between 12.2 and 15.7% for sideboards and between 19.7 and 24% for planks, the initial moisture content was 112...122% and 62...87% respectively. The moisture content distribution is shown by statistial diagrams. The total energy consumption was approx. 830 kcal per kg of water removed or approx. 1280 Mcal per standard at one plant, and according to works' statistics at another plant was rated at an annual average of 880 to 1010 kcal per kg water removed or 1160 to 1290 Mcal per standard, the energy consumption increasing with time, probably caused by corrosion in the heat exchangers. [ABSTRACT FROM AUTHOR]