It was declared to be "the greatest decentralisation of power in a generation," a move that would "pull down the Whitehall barricades". The Localism Act, passed in November 2011 after much anticipation, would put planning power in the hands of communities, "giving local people a real voice to say where they think new houses, business and shops should go – and what they should look like."

Seizing power from central government and putting it in the hands of the people, who would dutifully come together, magic markers in hand, to draw up neighbourhood plans, sounded nothing short of revolutionary. Yet more than a year later, not many of these "local people" are sure how it works. Even to many planners, the finer points of neighbourhood planning remain a mystery.

A new project at London's Architecture Foundation, masterminded by young architecture practice We Made That, aims to tackle this problem and put the workings of localism on public show for all to explore – and take part in.

"We were fascinated by the fact that communities were being given the power to write their own future, and yet they weren't being shown how to do it," says Holly Lewis, co-director of the practice with Oliver Goodhall. "The built environment professions haven't traditionally been very open or communicative, and people aren't really taught about planning at school or on TV – it's a very murky process. You may be familiar with house extensions, but the idea of being able to write policy is completely alien."

The Open Office, which will run for the next five weeks at the Architecture Foundation's street-fronting gallery in Southwark, is conceived as a live project space, part "Citizens Urban Advice Bureau", part functioning practice. Staffed by We Made That, along with a changing group of six to eight volunteers, the team will explore different case study areas on a week-by-week basis – from the emerging neighbourhood plan for Hackney's Chatsworth Road, to Croydon town centre and the Southall industrial area.

"We're trying to create an open forum for thinking about what localism – from neighbourhood planning to the National Planning Policy Framework – actually means in practice," says Lewis. "We don't have all the answers, but we're hoping to bring people together, from council planning officers to local residents, who do."

The research will be accumulated on the walls of the gallery, culminating in a weekly Friday pin-up, open to all, with invited guest critics. Operating from Tuesday to Saturday, 12–6pm, the studio will also be open for drop-in visits, featuring a library of literature on the subject and workstations for people to get involved.

Supported by arts organisation Openvizor, the project is the result of the Architecture Foundation's first ever open call for ideas to activate its ground-floor project space, and represents a bold new direction for the live, public-facing potential of the organisation. The Open Office may only be a short-term one-off initiative, but it looks set to raise important questions about the future of participatory planning, and help unravel what the opaque implications of the localism act actually mean.

• Oliver Wainwright will be chairing the final session, Learning from The Open Office, on Wednesday 20 March, from 7pm, at the Architecture Foundation.