ews-calendar-hours is an AngularJS app that calculates hours spent for exchange calendar on a selected range. It is based on the app from aronwoost (https://github.com/aronwoost/google-calendar-hours) and adapted for exchange calendar.
https://ews-calendar-hours.herokuapp.com/
To build the app use grunt:
# install
npm install -g grunt-cli bower
npm install
bower install
# test
grunt serve
Open : http://localhost:9000
MIT