The National Capital Commission is responsible for protecting the Chateau Laurier.

     The NCC released a statement about a proposed expansion of the building:
"The Chateau Laurier is part of the National Capital's iconic skyline. But as it's privately owned, and on private property, the NCC has no official role in approving the design of the addition." (July 13, 2019.)
Well, the hotel was privately owned and on private land in 2005, yet the Crown corporation dismissed any notion that the landmark could be altered or significantly expanded:
Policies
"The NCC, working with Parks Canada, Public Works and Government Services and the National Arts Centre will lead planning, development, programming and commemoration initiatives with the Rideau Canal Area, in cooperation with the City of Ottawa and other non-federal partners...
An Area Plan will be prepared for the Rideau Canal character area, to further develop and elaborate upon a number of policy directions identified in this section.
To preserve and enrich character
  "Preserve the historic character of the Chateau Laurier Hotel and the Government Conference Centre building (former Ottawa Union Station), key buildings in the Core Area." (From: NCC "Canada's Capital Core Area Sector Plan" - June 2005, Page 108/173.)

I am celebrating my birthday at Zoe's Lounge, Chateau Laurier, July 2019.