Over the past few years I've been uncovering many small Oases throughout Berlin. Most accessible in the summer... But some of my year long favourites are...
Amerika Gedenkbibliothek - beautiful spacious cool space to read or work in
Cafe in Bode Museum
Sarah Wiener at Hamburger Bahnhof
Around the corner a new cafe just opened up that I can see myself spending many hours in in the near future. When I remember what it is called I'll post it here.
One of my favourite things to do when I need a bit of time alone, or need to get out of the heat, is to go to one of the many museums in Berlin. They offer yearly passes for 80 Euros (40 Euros if you are a student) for all of the special permanent exhibitions. It's a steal... especially if you're not a fan of the crowds on the weekly free nights!