Hubbell Realty Co. said it will start work this month on the $7 million renovation of the Mitchell Transmission building at 1400 Locust St. The building will be renamed 14Forty and will feature 37 one- and two-bedroom market-rate apartments, 57 indoor parking spaces and 3,500 square feet of retail and office space. Lofts range from 530 square feet to more than 1,000 square feet. Financing was assisted by federal and state historic tax credits, enterprise zone tax credits, EZ sales tax rebate, brownfields tax credits and a 10-year tax abatement from the city of Des Moines, Kris Saddoris, vice president of development, said in a news release.