Bangladesh is known for its scorching temperatures, but many do not have electricity to power an aircon. Now there is Eco-Cooler, a DIY system that uses just plastic bottles and cardboard.
http://www.dailymail.co.uk/sciencetech/article-3635710/How-cool-apartment-free-Electricity-free-DIY-aircon-uses-old-plastic-bottles-used-used-25-000-Indian-homes.html