Founded in 1998, the firm helps developers win planning permissions by working closely with communities and their representatives. It claims to have most of the UK's 25 largest housebuilders as clients, as well as companies in the retail, waste, logistics and airport sectors. The agency employs 35 staff in offices in Reading, Cardiff, Manchester and London.
Isis's investment values the business at £8.8m.
Green Issues has also appointed Tim Trotter as non-executive chairman. Trotter founded Ludgate Group in the 1980s and sold it to Interpublic in the 1990s.