A sealed glazing unit with 3 horisontal and 3 vertical bars and a reference glazing without bars have been tested in a guarded hotbox. The difference in measured heat loss coefficient between the two test objects is a measure of the thermal influence of the bars. The difference in heat loss coefficent was found to 1.9 and 1.5 W/(m2 K) respectively. The difference was larger than expected. Opening of the sealed glazing unit showed that the gap distance only was 1/3 of the expected.