diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
index ad0f14cae..d9caa5ce1 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
@@ -813,4 +813,69 @@ public class BaseCalendar extends BaseEntity implements IWorkHours {
         return workableHours;
     }
 
+    protected boolean thereAreAvailableHoursFrom(LocalDate start,
+            ResourcesPerDay resourcesPerDay, int hoursToAllocate) {
+        LocalDate expiringDate = getAvailabilityExpiringDate();
+        if (expiringDate == null) {
+            return !onlyGivesZeroHours();
+        }
+        return thereAreHoursUntil(hoursToAllocate, resourcesPerDay, start,
+                expiringDate);
+    }
+
+    public boolean onlyGivesZeroHours() {
+        CalendarData last = lastCalendarData();
+        return last.isEmpty();
+    }
+
+    public boolean onlyGivesZeroHours(Days each) {
+        CalendarData last = lastCalendarData();
+        return last.isEmptyFor(each);
+    }
+
+    private CalendarData lastCalendarData() {
+        return calendarDataVersions.get(calendarDataVersions.size() - 1);
+    }
+
+    private boolean thereAreHoursUntil(int hoursToAllocate,
+            ResourcesPerDay resourcesPerDay, LocalDate start,
+            LocalDate expiringDate) {
+        int hoursSum = 0;
+        int days = org.joda.time.Days.daysBetween(start, expiringDate)
+                .getDays();
+        for (int i = 0; i < days; i++) {
+            LocalDate current = start.plusDays(i);
+            hoursSum += toHours(current, resourcesPerDay);
+            if (hoursSum >= hoursToAllocate) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private LocalDate getAvailabilityExpiringDate() {
+        List<CalendarAvailability> availabilities = getCalendarAvailabilities();
+        if (availabilities.isEmpty()) {
+            return null;
+        }
+        CalendarAvailability last = availabilities.get(0);
+        for (CalendarAvailability each : availabilities) {
+            LocalDate startDate = each.getStartDate();
+            if (startDate.compareTo(last.getStartDate()) > 0) {
+                last = each;
+            }
+        }
+        return last.getEndDate();
+    }
+
+    private List<CalendarException> getExceptionsFrom(LocalDate start) {
+        List<CalendarException> result = new ArrayList<CalendarException>();
+        for (CalendarException each : exceptions) {
+            if (each.getDate().compareTo(start) >= 0) {
+                result.add(each);
+            }
+        }
+        return result;
+    }
+
 }
\ No newline at end of file
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CalendarData.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CalendarData.java
index af6726267..c15043579 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CalendarData.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CalendarData.java
@@ -132,4 +132,28 @@ public class CalendarData extends BaseEntity {
         this.expiringDate = null;
     }
 
+    public boolean isPosteriorTo(LocalDate date) {
+        return expiringDate == null || expiringDate.compareTo(date) > 0;
+    }
+
+    boolean isEmpty() {
+        for (Days each : Days.values()) {
+            if (!isEmptyFor(each)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    boolean isEmptyFor(Days day) {
+        Integer hours = getHours(day);
+        if (!isDefault(day) && hours > 0) {
+            return false;
+        } else if (isDefault(day) && getParent() != null
+                && !parent.onlyGivesZeroHours(day)) {
+            return false;
+        }
+        return true;
+    }
+
 }
diff --git a/navalplanner-business/src/test/java/org/navalplanner/business/test/calendars/entities/BaseCalendarTest.java b/navalplanner-business/src/test/java/org/navalplanner/business/test/calendars/entities/BaseCalendarTest.java
index 106696f1f..17d03c127 100644
--- a/navalplanner-business/src/test/java/org/navalplanner/business/test/calendars/entities/BaseCalendarTest.java
+++ b/navalplanner-business/src/test/java/org/navalplanner/business/test/calendars/entities/BaseCalendarTest.java
@@ -106,6 +106,31 @@ public class BaseCalendarTest {
         calendar.addExceptionDay(christmasDay);
     }
 
+    @Test
+    public void testOnlyGivesZeroHoursWhenThereIsNoParent() {
+        BaseCalendar calendar = createBasicCalendar();
+        assertFalse(calendar.onlyGivesZeroHours());
+        initializeAllToZeroHours(calendar);
+        assertTrue(calendar.onlyGivesZeroHours());
+    }
+
+    private void initializeAllToZeroHours(BaseCalendar calendar) {
+        for (Days each : Days.values()) {
+            calendar.setHours(each, 0);
+        }
+    }
+
+    @Test
+    public void testOnlyGivesZeroHoursWhenThereIsParent() {
+        BaseCalendar calendar = createBasicCalendar();
+        initializeAllToZeroHours(calendar);
+        BaseCalendar parent = createBasicCalendar();
+        calendar.setParent(parent);
+        assertTrue(calendar.onlyGivesZeroHours());
+        calendar.setDefault(Days.MONDAY);
+        assertFalse(calendar.onlyGivesZeroHours());
+    }
+
     public static BaseCalendar createChristmasCalendar() {
         BaseCalendar calendar = createBasicCalendar();
         addChristmasAsExceptionDay(calendar);