Called Square One District, the development will encompass 130 acres of land and be home to 18 million square feet of new space, of which 13 million is slated for residential. The total is equivalent to about one-fifth of the total rentable office space in downtown Toronto, according to commercial real estate brokers.Home builder Daniels Corp. will partner with Oxford and AIMCo on the first phase of development that includes a 36-storey apartment building and a 48-storey condo tower. Construction is expected to start this summer.