Yes, you can use the timeZone attribute of rich:calendar to specify timezone format. Or even better, call it from yr backing bean where you can get Timezone from user profile

<rich:calendar
value="#{bean.value}"
datePattern="#{bean.datePattern}"
timeZone="#{bean.timeZone}"

 public TimeZone getTimeZone() {
 return this.getUserProfile().getTimeZone();
 }