Infiltration heat recovery is the process that occurs when a building envelope acts as a heat exchanger for infiltrating air. This heat recovery process results in a reduced heat loss compared to predictions that use only flow rate and the total difference in enthalpy between inside and outside air. A series of experiments show the relationship between infiltration flow rate and heat loss in a test cell, with an emphasis on the high flow rate regime. A 3.5-m³ test cell was built with standard light-frame construction and one removable panel, to allow testing of wall sections with different engineered flow path lengths. Experiments were conducted with two different wall sections and at six different infiltration flow rates. Experimentally determined heat recovery factors are compared to computational fluid dynamics and agree to within approximately 15%.