def to_dict(self):
        m = obj_to_dict(self)
        m['energy_type'] = self.get_energy_type_display()
        m['energy_units'] = self.get_energy_units_display()
        return m
serializes Meter to python dict, JSON safe
dataset/ETHPy150Open buildingenergy/buildingenergy-platform/seed/models.py/Meter.to_dict