The venue was announced in September 2014 as the flagship of the Guardian Membership scheme.
Viner and Pemsel said: "We do not believe that the concept we had planned for the Midland Goods Shed now fits with our business strategy. We are, as such, proposing to exit the lease and have advised our landlord, contractors and programming partners accordingly."
The letter adds: "These proposals form the basis of a collective consultation process. We have elected employee representatives and have in place NUJ and Unite representatives across the organisation.
"A meeting was held earlier today with these representatives, marking the start of that collective consultation process, which we currently envisage will take at least eight weeks.
"While we are confident these proposals will make a significant contribution to our target of reducing our current cost base by 20 per cent, we will continue to take the necessary action to manage our cost base and sustained market volatility in order to protect our journalism in perpetuity."
Guardian National Union of Journalists father of chapel Brian Williams said: "We are encouraged by the fact the company is seeking voluntary redundancies and is looking to mitigate potential job losses by finding other cost-cutting measures.”
NUJ general secretary Michelle Stanistreet said: "This is a major blow for the staff of the Guardian and Observer and for journalism as a whole. We will oppose any compulsory redundancies. This news together with the loss of jobs as the Independent newspapers fold presents a very worrying situation for the future of newspapers."