The DaylightBias property specifies a bias value to be used during local time translations that occur during daylight time. ...

The DaylightBias property specifies a bias value to be used during local time translations that occur during daylight time. This member is ignored if a value for the DaylightDay member is not supplied. The value of this member is added to the Bias member to form the bias used during daylight time. In most time zones, the value of this member is -60.