You can see some of this in action in a case study - Brussels region. You could argue that the local authority were both the facilitator and regulator.
Firstly in 2004, they involved local stakeholders with free advice, financial incentives, an Energy Challenge and by helping public property managers (schools, hospitals, swimming pools, etc.) install an energy management system at a reduced cost.
In 2008, they moved on to an “exemplary buildings competition” to provide financial incentives to building owners, whilst reinforcing and stimulating the expertise of architects.These ultra-low energy buildings require little energy for space heating or cooling, are retrofitted, promote eco-design, are of high architectural quality and financially and technically reproducible.
From 2010 onwards, the local authority introduced progressively ambitious regulationatory frameworks mandating all new public buildings meet the passive standard.
An urban laboratory of energy efficient buildings (Energy Cities, 2016)