By Julia Neel of Women's Wear Daily LONDON — Nike has launched a new app that aims to help guide apparel designers to make informed decisions on materials based on sustainability. The tool is free to download from iTunes now and has been created to guide designers through four environmental impact areas: water, energy, chemistry and waste, as well as whether the material uses recycled or organic content. The data have been drawn from Nike’s Materials Sustainability Index (MSI) over the last seven years and is presented in a clear format that offers direct comparisons and fast insights on how different materials stack up on a sustainable level. “Waste is the new gold,” said the brand’s vice president of sustainable business and fashion Hannah Jones at the app’s London launch. “It’s a new way of thinking. Eight years ago, sustainability was considered one of the world’s great innovation challenges. It was always seen as a bit ‘granola’, a bit less. There’d be a compromi…