Sian Reid has had a longstanding commitment to green issues. In her twenties she worked as an editorial assistant at Resurgence magazine. This magazine is a pioneering advocate of sustainable living. She also volunteered at the Centre for Alternative Technology, Machynlleth, Wales. The Centre demonstrates, on the ground, practical ways of addressing climate change, pollution, and waste of precious resources. Its projects cover renewable energy, environmental building, energy efficiency, organic growing and alternative sewage systems.

As Cambridge's Executive Councillor for Climate Change and Growth, Sian has placed climate change at the centre of the City Council's work and has led a campaign to reduce the city's carbon footprint through the Climate Change Charter, the Climate Change Fund, and Sustainable City Grants. Practical achievements include introducing LED lighting into the City's multi-storey car parks.

Sian has put Cambridge City Council at the forefront of UK local authorities by successfully promoting zero carbon housing policies for new developments in the North West of Cambridge, where almost 3000 homes will be built to Code Level 5 sustainability standards. This is a first for the UK and is a step ahead of national policy. She has led the development of another national first, Cambrige's Sustainable Urban Drainage strategy. It will deliver better water management, and encourage biodiversity. Experts from across the UK came to its recent launch. She has commissioned a new study 'Decarbonising Cambridge' which is examining how Cambridge may best use renewable energy and decentralised energy systems.

Sian was in 2006 co-founder with two other Cambridge residents of the non-profit Close the Door Campaign, backed by Cambridge City Council. This asks retailers to conserve energy by keeping their shop front doors closed. The campaign has secured the support of more than 290 retailers right across Cambridge. It received an Environment Agency award in 2008. With an Esmee Fairbairn Foundation grant it is now funding an MPhil at the University of Cambridge Engineering Department to quantify the energy saved through closing doors.

The Close the Door campaign is the first of its kind in the UK, and has achieved a national profile, with widespread press and TV coverage. In addition to BBC Cambridgeshire and the Cambridge News, it has featured in ITV News, Radio 5 Live, Radio 4 You and Yours, and The Guardian. The campaign has now spread to several other cities.