Current government employees are often forced to work onsite for jobs that could very easily be performed by teleworking. The hinderance to moving most of this work to a telework arrangement is solely organizational resistance to change.
If federal staff were required to telework 20% the following benefits could be realized almost immediately with a net savings to the federal government. 1. Traffic congestion would be dramatically reduced. 2. Road constuction and maintenance costs would decrease. 3. Carbon emissions would be reduced. 4. Government facilities and utility costs would decline. 5. Everyone living near government facilities would see improved quality of life because of reduced commute times.
20% is a reasonable starting point but long term goals should be higher.