Figure 1 shows a comparison between a Dawson thermally broken door top rail and a traditional Dawson non-thermally broken top rail. The U-Value listed under each image represents the entire door system calculated using the respective construction methods.
The door on the left side, without the thermal break, has a calculated U-value of .8, which does not meet the current industry standard U-value of .77. The thermally broken door on the right side has a calculated U-value of .47, which far exceeds all current energy requirements.
The coefficient of heat transfer (U-value) was calculated by Dawson engineers using a simulation performed according to the NFRC 100 procedure and the ISO 15099 standard. THERM version 7.7.10 and WINDOW version 7.7.10 software developed by the Lawrence Berkley National Laboratory were used to perform all calculations.Thermal Break in Doors: What You Need to Know