The Landsat calibration in ENVI will convert the thermal band from TM to temperature.  ENVI does have some thermal tools to calculate emissivity and temperature under Basic Tools ->Preprocessing->Calibration Utilities ->Calculate Emissivity.  However, these tools work best when you have multiple thermal bands and with TM you only have 1 band.  So while you can run Reference Channel Emissivity or Emissivity Normalization to get temperature, it assumes the emissivity is the same for the entire band.  Alpha residuals requires more than one thermal band so you could use ETM data for this.  I am not sure that these methods provide a better estimate of temperature than the basic TM calibration tool.

Thank you for your feedback. I just wanted to clarify one point. You mentioned the Landsat calibration tool converts the thermal band to temperature but I thought it only converted it to radiance? and then needs to be converted to temperature using either Reference channel or Emissivity Normalization?

The Landsat calibration tool in ENVI will convert the thermal band to either radiance or temperature.  Since the dialog is generic, you would choose 'Reflectance' output for the thermal band which will give you temperature in Kelvin.  You do not need to use the Emissivity tools to get temperature for Landsat.

great thank you!