private void BuildBasicConsumption(int consumption)
        {
            //(5€ *12 months = 60 € base costs + 3500 kWh / year * 22 cent / kWh = 770 € consumption costs)
            var basicCost       = 60 + (consumption * 0.22);
            var basicTariffCost = new TariffCosts()
            {
                TariffName  = "Basic Electric Tariff",
                AnnualCosts = basicCost
            };

            _tariffCosts.Add(basicTariffCost);
        }
        private void BuildPackagedConsumption(int consumption)
        {
            double packagedCost;

            if (consumption <= 4000)
            {
                packagedCost = 800;
            }
            else
            {
                packagedCost = ((consumption - 4000) * 0.30) + 800;
            }

            var packagedTariffCost = new TariffCosts()
            {
                TariffName  = "Packaged Tariff",
                AnnualCosts = packagedCost
            };

            _tariffCosts.Add(packagedTariffCost);
        }