Express.js 4.0 -- use separate view directory for each router

Question

I'm using Express 4 routers to separate out two different app functions. Each app function has its own set of ejs view templates, with conflicting names (e.g both have a search.ejs).

How can I specify the router to use only a particular view directory to render views? For example, the view directory would look like this:

views/
   app1/
      - search.ejs
      - index.ejs
   app2/
      - search.ejs
      - index.ejs