The energy performance of buildings in cold climates, with a considerable annual heating demand, is dependent on the ventilation air change rates (ACH). Buildings utilized for commercial use often have high annual ventilation heating demand due to high ACH required from indoor air quality aspect. In order for these buildings to have a reasonable energy performance a heat recovery system is often used to recover heat from the exhaust air to the makeup air. There are different variations of these systems; one that is sometimes used in Sweden is a run around coil heat recovery system. The present paper summarizes the findings from previous studies [5-7], and presents a comparative study, for three different cases; the traditional run-around coil heat recovery system; with a three stage on/off controlled heat pump retrofitted into the system; and with a variable capacity heat pump retrofitted into the system. Annual modeling (using TRNSYS) shows that by retrofitting a well-designed 3 stage heat pump to the system the annual heat recovery rate for the Stockholm case can be increased from 47% to 65%. For a retrofitted variable speed capacity heat pump for the Stockholm case the annual heat recovery improves from 47% to 66%. The modeling also shows that a well designed variable speed heat pump can cover 81% of the total ventilation heating demand and a well designed multi stage heat pump 77% of the total ventilation heating demand. (C) 2011 Elsevier Ltd. All rights reserved.