I decided to give the Cold Brew (rather as opposed to cold drip) lark a go yesterday. I had some Yemen Bani Ismail beans that I had roasted using a revolutionary technique called 'Error 7', and which rendered the beans unsuitable for espresso. 100g of ground coffee, 580mls of water, left in the dining room (at about 15 degrees C) for 8 hours. I'm really impressed. Won't last long.