def annual_heating_design_day_990(self):
        """A design day object representing the annual 99.0% heating design day."""
        if bool(self._winter_des_day_dict) is True:
            return DesignDay.from_ashrae_dict_heating(
                self._winter_des_day_dict, self.location, True,
                self._stand_press_at_elev)
        else:
            return None
A design day object representing the annual 99.0% heating design day.