diff --git a/homeassistant/__init__.py b/homeassistant/__init__.py
index 5b3e4fd8b9e..7d6a1f03d00 100644
--- a/homeassistant/__init__.py
+++ b/homeassistant/__init__.py
@@ -12,7 +12,6 @@ import logging
 import threading
 import enum
 import re
-import datetime as dt
 import functools as ft
 
 from homeassistant.const import (
@@ -22,6 +21,7 @@ from homeassistant.const import (
     EVENT_SERVICE_EXECUTED, ATTR_SERVICE_CALL_ID, EVENT_SERVICE_REGISTERED,
     TEMP_CELCIUS, TEMP_FAHRENHEIT, ATTR_FRIENDLY_NAME)
 import homeassistant.util as util
+import homeassistant.util.dt as date_util
 
 DOMAIN = "homeassistant"
 
@@ -107,7 +107,20 @@ class HomeAssistant(object):
 
     def track_point_in_time(self, action, point_in_time):
         """
-        Adds a listener that fires once at or after a spefic point in time.
+        Adds a listener that fires once after a spefic point in time.
+        """
+        utc_point_in_time = date_util.as_utc(point_in_time)
+
+        @ft.wraps(action)
+        def utc_converter(utc_now):
+            """ Converts passed in UTC now to local now. """
+            action(date_util.as_local(utc_now))
+
+        self.track_point_in_utc_time(utc_converter, utc_point_in_time)
+
+    def track_point_in_utc_time(self, action, point_in_time):
+        """
+        Adds a listener that fires once after a specific point in UTC time.
         """
 
         @ft.wraps(action)
@@ -133,11 +146,19 @@ class HomeAssistant(object):
         self.bus.listen(EVENT_TIME_CHANGED, point_in_time_listener)
         return point_in_time_listener
 
+    # pylint: disable=too-many-arguments
+    def track_utc_time_change(self, action,
+                              year=None, month=None, day=None,
+                              hour=None, minute=None, second=None):
+        """ Adds a listener that will fire if time matches a pattern. """
+        self.track_time_change(
+            action, year, month, day, hour, minute, second, utc=True)
+
     # pylint: disable=too-many-arguments
     def track_time_change(self, action,
                           year=None, month=None, day=None,
-                          hour=None, minute=None, second=None):
-        """ Adds a listener that will fire if time matches a pattern. """
+                          hour=None, minute=None, second=None, utc=False):
+        """ Adds a listener that will fire if UTC time matches a pattern. """
 
         # We do not have to wrap the function with time pattern matching logic
         # if no pattern given
@@ -153,6 +174,9 @@ class HomeAssistant(object):
                 """ Listens for matching time_changed events. """
                 now = event.data[ATTR_NOW]
 
+                if not utc:
+                    now = date_util.as_local(now)
+
                 mat = _matcher
 
                 if mat(now.year, year) and \
@@ -303,7 +327,7 @@ def create_worker_pool():
 
         for start, job in current_jobs:
             _LOGGER.warning("WorkerPool:Current job from %s: %s",
-                            util.datetime_to_str(start), job)
+                            date_util.datetime_to_local_str(start), job)
 
     return util.ThreadPool(job_handler, MIN_WORKER_THREAD, busy_callback)
 
@@ -331,7 +355,7 @@ class Event(object):
         self.data = data or {}
         self.origin = origin
         self.time_fired = util.strip_microseconds(
-            time_fired or dt.datetime.now())
+            time_fired or date_util.utcnow())
 
     def as_dict(self):
         """ Returns a dict representation of this Event. """
@@ -339,7 +363,7 @@ class Event(object):
             'event_type': self.event_type,
             'data': dict(self.data),
             'origin': str(self.origin),
-            'time_fired': util.datetime_to_str(self.time_fired),
+            'time_fired': date_util.datetime_to_str(self.time_fired),
         }
 
     def __repr__(self):
@@ -472,13 +496,13 @@ class State(object):
         self.entity_id = entity_id.lower()
         self.state = state
         self.attributes = attributes or {}
-        self.last_updated = last_updated or dt.datetime.now()
+        self.last_updated = last_updated or date_util.utcnow()
 
         # Strip microsecond from last_changed else we cannot guarantee
         # state == State.from_dict(state.as_dict())
         # This behavior occurs because to_dict uses datetime_to_str
         # which does not preserve microseconds
-        self.last_changed = util.strip_microseconds(
+        self.last_changed = date_util.strip_microseconds(
             last_changed or self.last_updated)
 
     @property
@@ -510,8 +534,8 @@ class State(object):
         return {'entity_id': self.entity_id,
                 'state': self.state,
                 'attributes': self.attributes,
-                'last_changed': util.datetime_to_str(self.last_changed),
-                'last_updated': util.datetime_to_str(self.last_updated)}
+                'last_changed': date_util.datetime_to_str(self.last_changed),
+                'last_updated': date_util.datetime_to_str(self.last_updated)}
 
     @classmethod
     def from_dict(cls, json_dict):
@@ -526,12 +550,12 @@ class State(object):
         last_changed = json_dict.get('last_changed')
 
         if last_changed:
-            last_changed = util.str_to_datetime(last_changed)
+            last_changed = date_util.str_to_datetime(last_changed)
 
         last_updated = json_dict.get('last_updated')
 
         if last_updated:
-            last_updated = util.str_to_datetime(last_updated)
+            last_updated = date_util.str_to_datetime(last_updated)
 
         return cls(json_dict['entity_id'], json_dict['state'],
                    json_dict.get('attributes'), last_changed, last_updated)
@@ -548,7 +572,7 @@ class State(object):
 
         return "<state {}={}{} @ {}>".format(
             self.entity_id, self.state, attr,
-            util.datetime_to_str(self.last_changed))
+            date_util.datetime_to_local_str(self.last_changed))
 
 
 class StateMachine(object):
@@ -585,7 +609,7 @@ class StateMachine(object):
         """
         Returns all states that have been changed since point_in_time.
         """
-        point_in_time = util.strip_microseconds(point_in_time)
+        point_in_time = date_util.strip_microseconds(point_in_time)
 
         with self._lock:
             return [state for state in self._states.values()
@@ -847,7 +871,7 @@ class Timer(threading.Thread):
 
         last_fired_on_second = -1
 
-        calc_now = dt.datetime.now
+        calc_now = date_util.utcnow
         interval = self.interval
 
         while not self._stop_event.isSet():
diff --git a/homeassistant/bootstrap.py b/homeassistant/bootstrap.py
index 4f323f34bea..2544ff5fa79 100644
--- a/homeassistant/bootstrap.py
+++ b/homeassistant/bootstrap.py
@@ -15,6 +15,7 @@ from collections import defaultdict
 
 import homeassistant
 import homeassistant.util as util
+import homeassistant.util.dt as date_util
 import homeassistant.config as config_util
 import homeassistant.loader as loader
 import homeassistant.components as core_components
@@ -183,13 +184,27 @@ def process_ha_core_config(hass, config):
     """ Processes the [homeassistant] section from the config. """
     hac = hass.config
 
+    def set_time_zone(time_zone_str):
+        """ Helper method to set time zone in HA. """
+        if time_zone_str is None:
+            return
+
+        time_zone = date_util.get_time_zone(time_zone_str)
+
+        if time_zone:
+            hac.time_zone = time_zone
+            date_util.set_default_time_zone(time_zone)
+        else:
+            _LOGGER.error("Received invalid time zone %s", time_zone_str)
+
     for key, attr in ((CONF_LATITUDE, 'latitude'),
                       (CONF_LONGITUDE, 'longitude'),
-                      (CONF_NAME, 'location_name'),
-                      (CONF_TIME_ZONE, 'time_zone')):
+                      (CONF_NAME, 'location_name')):
         if key in config:
             setattr(hac, attr, config[key])
 
+    set_time_zone(config.get(CONF_TIME_ZONE))
+
     for entity_id, attrs in config.get(CONF_CUSTOMIZE, {}).items():
         Entity.overwrite_attribute(entity_id, attrs.keys(), attrs.values())
 
@@ -202,7 +217,8 @@ def process_ha_core_config(hass, config):
             hac.temperature_unit = TEMP_FAHRENHEIT
 
     # If we miss some of the needed values, auto detect them
-    if None not in (hac.latitude, hac.longitude, hac.temperature_unit):
+    if None not in (
+            hac.latitude, hac.longitude, hac.temperature_unit, hac.time_zone):
         return
 
     _LOGGER.info('Auto detecting location and temperature unit')
@@ -227,7 +243,7 @@ def process_ha_core_config(hass, config):
         hac.location_name = info.city
 
     if hac.time_zone is None:
-        hac.time_zone = info.time_zone
+        set_time_zone(info.time_zone)
 
 
 def _ensure_loader_prepared(hass):
diff --git a/homeassistant/components/device_tracker/__init__.py b/homeassistant/components/device_tracker/__init__.py
index 6d4db7ad7ed..40dd6e5150e 100644
--- a/homeassistant/components/device_tracker/__init__.py
+++ b/homeassistant/components/device_tracker/__init__.py
@@ -8,11 +8,12 @@ import logging
 import threading
 import os
 import csv
-from datetime import datetime, timedelta
+from datetime import timedelta
 
 from homeassistant.loader import get_component
 from homeassistant.helpers import validate_config
 import homeassistant.util as util
+import homeassistant.util.dt as dt_util
 
 from homeassistant.const import (
     STATE_HOME, STATE_NOT_HOME, ATTR_ENTITY_PICTURE, ATTR_FRIENDLY_NAME,
@@ -113,7 +114,7 @@ class DeviceTracker(object):
             """ Reload known devices file. """
             self._read_known_devices_file()
 
-            self.update_devices(datetime.now())
+            self.update_devices(dt_util.utcnow())
 
             dev_group.update_tracked_entity_ids(self.device_entity_ids)
 
@@ -125,7 +126,7 @@ class DeviceTracker(object):
         seconds = range(0, 60, seconds)
 
         _LOGGER.info("Device tracker interval second=%s", seconds)
-        hass.track_time_change(update_device_state, second=seconds)
+        hass.track_utc_time_change(update_device_state, second=seconds)
 
         hass.services.register(DOMAIN,
                                SERVICE_DEVICE_TRACKER_RELOAD,
@@ -226,7 +227,7 @@ class DeviceTracker(object):
         self.untracked_devices.clear()
 
         with open(known_dev_path) as inp:
-            default_last_seen = datetime(1990, 1, 1)
+            default_last_seen = dt_util.utcnow().replace(year=1990)
 
             # To track which devices need an entity_id assigned
             need_entity_id = []
diff --git a/homeassistant/components/history.py b/homeassistant/components/history.py
index a288d5471d9..2717cdccd7f 100644
--- a/homeassistant/components/history.py
+++ b/homeassistant/components/history.py
@@ -5,10 +5,11 @@ homeassistant.components.history
 Provide pre-made queries on top of the recorder component.
 """
 import re
-from datetime import datetime, timedelta
+from datetime import timedelta
 from itertools import groupby
 from collections import defaultdict
 
+import homeassistant.util.dt as date_util
 import homeassistant.components.recorder as recorder
 
 DOMAIN = 'history'
@@ -30,7 +31,7 @@ def last_5_states(entity_id):
 
 def state_changes_during_period(start_time, end_time=None, entity_id=None):
     """
-    Return states changes during period start_time - end_time.
+    Return states changes during UTC period start_time - end_time.
     """
     where = "last_changed=last_updated AND last_changed > ? "
     data = [start_time]
@@ -64,17 +65,17 @@ def state_changes_during_period(start_time, end_time=None, entity_id=None):
     return result
 
 
-def get_states(point_in_time, entity_ids=None, run=None):
+def get_states(utc_point_in_time, entity_ids=None, run=None):
     """ Returns the states at a specific point in time. """
     if run is None:
-        run = recorder.run_information(point_in_time)
+        run = recorder.run_information(utc_point_in_time)
 
-        # History did not run before point_in_time
+        # History did not run before utc_point_in_time
         if run is None:
             return []
 
     where = run.where_after_start_run + "AND created < ? "
-    where_data = [point_in_time]
+    where_data = [utc_point_in_time]
 
     if entity_ids is not None:
         where += "AND entity_id IN ({}) ".format(
@@ -93,9 +94,9 @@ def get_states(point_in_time, entity_ids=None, run=None):
     return recorder.query_states(query, where_data)
 
 
-def get_state(point_in_time, entity_id, run=None):
+def get_state(utc_point_in_time, entity_id, run=None):
     """ Return a state at a specific point in time. """
-    states = get_states(point_in_time, (entity_id,), run)
+    states = get_states(utc_point_in_time, (entity_id,), run)
 
     return states[0] if states else None
 
@@ -128,7 +129,7 @@ def _api_last_5_states(handler, path_match, data):
 def _api_history_period(handler, path_match, data):
     """ Return history over a period of time. """
     # 1 day for now..
-    start_time = datetime.now() - timedelta(seconds=86400)
+    start_time = date_util.utcnow() - timedelta(seconds=86400)
 
     entity_id = data.get('filter_entity_id')
 
diff --git a/homeassistant/components/logbook.py b/homeassistant/components/logbook.py
index a8299fbd6ed..4d1e5ba8e00 100644
--- a/homeassistant/components/logbook.py
+++ b/homeassistant/components/logbook.py
@@ -4,14 +4,13 @@ homeassistant.components.logbook
 
 Parses events and generates a human log
 """
-from datetime import datetime
 from itertools import groupby
 
 from homeassistant import State, DOMAIN as HA_DOMAIN
 from homeassistant.const import (
     EVENT_STATE_CHANGED, STATE_HOME, STATE_ON, STATE_OFF,
     EVENT_HOMEASSISTANT_START, EVENT_HOMEASSISTANT_STOP)
-import homeassistant.util as util
+import homeassistant.util.dt as dt_util
 import homeassistant.components.recorder as recorder
 import homeassistant.components.sun as sun
 
@@ -38,10 +37,11 @@ def setup(hass, config):
 
 def _handle_get_logbook(handler, path_match, data):
     """ Return logbook entries. """
-    start_today = datetime.now().date()
+    start_today = dt_util.now().date()
 
     handler.write_json(humanify(
-        recorder.query_events(QUERY_EVENTS_AFTER, (start_today,))))
+        recorder.query_events(
+            QUERY_EVENTS_AFTER, (dt_util.as_utc(start_today),))))
 
 
 class Entry(object):
@@ -60,7 +60,7 @@ class Entry(object):
     def as_dict(self):
         """ Convert Entry to a dict to be used within JSON. """
         return {
-            'when': util.datetime_to_str(self.when),
+            'when': dt_util.datetime_to_str(self.when),
             'name': self.name,
             'message': self.message,
             'domain': self.domain,
diff --git a/homeassistant/components/recorder.py b/homeassistant/components/recorder.py
index 6856ce4d7b5..ad4d2f3caa4 100644
--- a/homeassistant/components/recorder.py
+++ b/homeassistant/components/recorder.py
@@ -15,6 +15,7 @@ import json
 import atexit
 
 from homeassistant import Event, EventOrigin, State
+import homeassistant.util.dt as date_util
 from homeassistant.remote import JSONEncoder
 from homeassistant.const import (
     MATCH_ALL, EVENT_TIME_CHANGED, EVENT_STATE_CHANGED,
@@ -60,8 +61,9 @@ def row_to_state(row):
     """ Convert a databsae row to a state. """
     try:
         return State(
-            row[1], row[2], json.loads(row[3]), datetime.fromtimestamp(row[4]),
-            datetime.fromtimestamp(row[5]))
+            row[1], row[2], json.loads(row[3]),
+            date_util.utc_from_timestamp(row[4]),
+            date_util.utc_from_timestamp(row[5]))
     except ValueError:
         # When json.loads fails
         _LOGGER.exception("Error converting row to state: %s", row)
@@ -72,7 +74,7 @@ def row_to_event(row):
     """ Convert a databse row to an event. """
     try:
         return Event(row[1], json.loads(row[2]), EventOrigin[row[3].lower()],
-                     datetime.fromtimestamp(row[5]))
+                     date_util.utc_from_timestamp(row[5]))
     except ValueError:
         # When json.loads fails
         _LOGGER.exception("Error converting row to event: %s", row)
@@ -113,10 +115,10 @@ class RecorderRun(object):
             self.start = _INSTANCE.recording_start
             self.closed_incorrect = False
         else:
-            self.start = datetime.fromtimestamp(row[1])
+            self.start = date_util.utc_from_timestamp(row[1])
 
             if row[2] is not None:
-                self.end = datetime.fromtimestamp(row[2])
+                self.end = date_util.utc_from_timestamp(row[2])
 
             self.closed_incorrect = bool(row[3])
 
@@ -166,7 +168,8 @@ class Recorder(threading.Thread):
         self.queue = queue.Queue()
         self.quit_object = object()
         self.lock = threading.Lock()
-        self.recording_start = datetime.now()
+        self.recording_start = date_util.utcnow()
+        self.utc_offset = date_util.now().utcoffset().total_seconds()
 
         def start_recording(event):
             """ Start recording. """
@@ -209,31 +212,33 @@ class Recorder(threading.Thread):
 
     def record_state(self, entity_id, state):
         """ Save a state to the database. """
-        now = datetime.now()
+        now = date_util.utcnow()
 
+        # State got deleted
         if state is None:
             info = (entity_id, '', "{}", now, now, now)
         else:
             info = (
                 entity_id.lower(), state.state, json.dumps(state.attributes),
-                state.last_changed, state.last_updated, now)
+                state.last_changed, state.last_updated, now, self.utc_offset)
 
         self.query(
             "INSERT INTO states ("
             "entity_id, state, attributes, last_changed, last_updated,"
-            "created) VALUES (?, ?, ?, ?, ?, ?)", info)
+            "created, utc_offset) VALUES (?, ?, ?, ?, ?, ?, ?)", info)
 
     def record_event(self, event):
         """ Save an event to the database. """
         info = (
             event.event_type, json.dumps(event.data, cls=JSONEncoder),
-            str(event.origin), datetime.now(), event.time_fired,
+            str(event.origin), date_util.utcnow(), event.time_fired,
+            self.utc_offset
         )
 
         self.query(
             "INSERT INTO events ("
-            "event_type, event_data, origin, created, time_fired"
-            ") VALUES (?, ?, ?, ?, ?)", info)
+            "event_type, event_data, origin, created, time_fired, utc_offset"
+            ") VALUES (?, ?, ?, ?, ?, ?)", info)
 
     def query(self, sql_query, data=None, return_value=None):
         """ Query the database. """
@@ -282,7 +287,7 @@ class Recorder(threading.Thread):
         def save_migration(migration_id):
             """ Save and commit a migration to the database. """
             cur.execute('INSERT INTO schema_version VALUES (?, ?)',
-                        (migration_id, datetime.now()))
+                        (migration_id, date_util.utcnow()))
             self.conn.commit()
             _LOGGER.info("Database migrated to version %d", migration_id)
 
@@ -341,6 +346,44 @@ class Recorder(threading.Thread):
 
             save_migration(2)
 
+        if migration_id < 3:
+            utc_offset = self.utc_offset
+
+            cur.execute("""
+                ALTER TABLE recorder_runs
+                ADD COLUMN utc_offset integer
+            """)
+
+            cur.execute("""
+                ALTER TABLE events
+                ADD COLUMN utc_offset integer
+            """)
+
+            cur.execute("""
+                ALTER TABLE states
+                ADD COLUMN utc_offset integer
+            """)
+
+            cur.execute("UPDATE schema_version SET performed=performed+?",
+                        (utc_offset,))
+
+            cur.execute("""
+                UPDATE recorder_runs SET utc_offset=?,
+                start=start + ?, end=end + ?, created=created + ?
+            """, [utc_offset]*4)
+
+            cur.execute("""
+                UPDATE events SET utc_offset=?,
+                time_fired=time_fired + ?, created=created + ?
+            """, [utc_offset]*3)
+
+            cur.execute("""
+                UPDATE states SET utc_offset=?, last_changed=last_changed + ?,
+                last_updated=last_updated + ?, created=created + ?
+            """, [utc_offset]*4)
+
+            save_migration(3)
+
     def _close_connection(self):
         """ Close connection to the database. """
         _LOGGER.info("Closing database")
@@ -357,18 +400,18 @@ class Recorder(threading.Thread):
 
         self.query(
             "INSERT INTO recorder_runs (start, created) VALUES (?, ?)",
-            (self.recording_start, datetime.now()))
+            (self.recording_start, date_util.utcnow()))
 
     def _close_run(self):
         """ Save end time for current run. """
         self.query(
             "UPDATE recorder_runs SET end=? WHERE start=?",
-            (datetime.now(), self.recording_start))
+            (date_util.utcnow(), self.recording_start))
 
 
 def _adapt_datetime(datetimestamp):
     """ Turn a datetime into an integer for in the DB. """
-    return time.mktime(datetimestamp.timetuple())
+    return time.mktime(date_util.as_utc(datetimestamp).timetuple())
 
 
 def _verify_instance():
diff --git a/homeassistant/components/sun.py b/homeassistant/components/sun.py
index a7228a1e42f..208d17167c6 100644
--- a/homeassistant/components/sun.py
+++ b/homeassistant/components/sun.py
@@ -30,7 +30,7 @@ except ImportError:
     # Error will be raised during setup
     ephem = None
 
-from homeassistant.util import str_to_datetime, datetime_to_str
+import homeassistant.util.dt as dt_util
 from homeassistant.helpers.entity import Entity
 from homeassistant.components.scheduler import ServiceEventListener
 
@@ -55,13 +55,21 @@ def is_on(hass, entity_id=None):
 
 
 def next_setting(hass, entity_id=None):
-    """ Returns the datetime object representing the next sun setting. """
+    """ Returns the local datetime object of the next sun setting. """
+    utc_next = next_setting_utc(hass, entity_id)
+
+    return dt_util.as_local(utc_next) if utc_next else None
+
+
+def next_setting_utc(hass, entity_id=None):
+    """ Returns the UTC datetime object of the next sun setting. """
     entity_id = entity_id or ENTITY_ID
 
     state = hass.states.get(ENTITY_ID)
 
     try:
-        return str_to_datetime(state.attributes[STATE_ATTR_NEXT_SETTING])
+        return dt_util.str_to_datetime(
+            state.attributes[STATE_ATTR_NEXT_SETTING])
     except (AttributeError, KeyError):
         # AttributeError if state is None
         # KeyError if STATE_ATTR_NEXT_SETTING does not exist
@@ -69,13 +77,21 @@ def next_setting(hass, entity_id=None):
 
 
 def next_rising(hass, entity_id=None):
-    """ Returns the datetime object representing the next sun rising. """
+    """ Returns the local datetime object of the next sun rising. """
+    utc_next = next_rising_utc(hass, entity_id)
+
+    return dt_util.as_local(utc_next) if utc_next else None
+
+
+def next_rising_utc(hass, entity_id=None):
+    """ Returns the UTC datetime object of the next sun rising. """
     entity_id = entity_id or ENTITY_ID
 
     state = hass.states.get(ENTITY_ID)
 
     try:
-        return str_to_datetime(state.attributes[STATE_ATTR_NEXT_RISING])
+        return dt_util.str_to_datetime(
+            state.attributes[STATE_ATTR_NEXT_RISING])
     except (AttributeError, KeyError):
         # AttributeError if state is None
         # KeyError if STATE_ATTR_NEXT_RISING does not exist
@@ -94,15 +110,15 @@ def setup(hass, config):
         logger.error("Latitude or longitude not set in Home Assistant config")
         return False
 
-    sun = Sun(hass, str(hass.config.latitude), str(hass.config.longitude))
-
     try:
-        sun.point_in_time_listener(datetime.now())
+        sun = Sun(hass, str(hass.config.latitude), str(hass.config.longitude))
     except ValueError:
         # Raised when invalid latitude or longitude is given to Observer
         logger.exception("Invalid value for latitude or longitude")
         return False
 
+    sun.point_in_time_listener(dt_util.utcnow())
+
     return True
 
 
@@ -113,8 +129,11 @@ class Sun(Entity):
 
     def __init__(self, hass, latitude, longitude):
         self.hass = hass
-        self.latitude = latitude
-        self.longitude = longitude
+        self.observer = ephem.Observer()
+        # pylint: disable=assigning-non-slot
+        self.observer.lat = latitude
+        # pylint: disable=assigning-non-slot
+        self.observer.long = longitude
 
         self._state = self.next_rising = self.next_setting = None
 
@@ -137,8 +156,8 @@ class Sun(Entity):
     @property
     def state_attributes(self):
         return {
-            STATE_ATTR_NEXT_RISING: datetime_to_str(self.next_rising),
-            STATE_ATTR_NEXT_SETTING: datetime_to_str(self.next_setting)
+            STATE_ATTR_NEXT_RISING: dt_util.datetime_to_str(self.next_rising),
+            STATE_ATTR_NEXT_SETTING: dt_util.datetime_to_str(self.next_setting)
         }
 
     @property
@@ -146,22 +165,19 @@ class Sun(Entity):
         """ Returns the datetime when the next change to the state is. """
         return min(self.next_rising, self.next_setting)
 
-    def update_as_of(self, point_in_time):
-        """ Calculate sun state at a point in time. """
-        utc_offset = datetime.utcnow() - datetime.now()
-        utc_now = point_in_time + utc_offset
-
+    def update_as_of(self, utc_point_in_time):
+        """ Calculate sun state at a point in UTC time. """
         sun = ephem.Sun()  # pylint: disable=no-member
 
-        # Setting invalid latitude and longitude to observer raises ValueError
-        observer = ephem.Observer()
-        observer.lat = self.latitude  # pylint: disable=assigning-non-slot
-        observer.long = self.longitude  # pylint: disable=assigning-non-slot
+        # pylint: disable=assigning-non-slot
+        self.observer.date = ephem.date(utc_point_in_time)
 
-        self.next_rising = ephem.localtime(
-            observer.next_rising(sun, start=utc_now))
-        self.next_setting = ephem.localtime(
-            observer.next_setting(sun, start=utc_now))
+        self.next_rising = self.observer.next_rising(
+            sun,
+            start=utc_point_in_time).datetime().replace(tzinfo=dt_util.UTC)
+        self.next_setting = self.observer.next_setting(
+            sun,
+            start=utc_point_in_time).datetime().replace(tzinfo=dt_util.UTC)
 
     def point_in_time_listener(self, now):
         """ Called when the state of the sun has changed. """
@@ -169,8 +185,9 @@ class Sun(Entity):
         self.update_ha_state()
 
         # Schedule next update at next_change+1 second so sun state has changed
-        self.hass.track_point_in_time(self.point_in_time_listener,
-                                      self.next_change + timedelta(seconds=1))
+        self.hass.track_point_in_utc_time(
+            self.point_in_time_listener,
+            self.next_change + timedelta(seconds=1))
 
 
 def create_event_listener(schedule, event_listener_data):
diff --git a/homeassistant/helpers/state.py b/homeassistant/helpers/state.py
index 43d48898303..18c68808e94 100644
--- a/homeassistant/helpers/state.py
+++ b/homeassistant/helpers/state.py
@@ -5,9 +5,9 @@ homeassistant.helpers.state
 Helpers that help with state related things.
 """
 import logging
-from datetime import datetime
 
 from homeassistant import State
+import homeassistant.util.dt as dt_util
 from homeassistant.const import (
     STATE_ON, STATE_OFF, SERVICE_TURN_ON, SERVICE_TURN_OFF, ATTR_ENTITY_ID)
 
@@ -26,7 +26,7 @@ class TrackStates(object):
         self.states = []
 
     def __enter__(self):
-        self.now = datetime.now()
+        self.now = dt_util.utcnow()
         return self.states
 
     def __exit__(self, exc_type, exc_value, traceback):
diff --git a/homeassistant/util.py b/homeassistant/util/__init__.py
similarity index 94%
rename from homeassistant/util.py
rename to homeassistant/util/__init__.py
index e50ac3f30cf..5c69fd02243 100644
--- a/homeassistant/util.py
+++ b/homeassistant/util/__init__.py
@@ -8,7 +8,7 @@ import collections
 from itertools import chain
 import threading
 import queue
-from datetime import datetime, timedelta
+from datetime import datetime
 import re
 import enum
 import socket
@@ -18,12 +18,17 @@ from functools import wraps
 
 import requests
 
+# DEPRECATED AS OF 4/27/2015 - moved to homeassistant.util.dt package
+# pylint: disable=unused-import
+from .dt import (  # noqa
+    datetime_to_str, str_to_datetime, strip_microseconds,
+    datetime_to_local_str, utcnow)
+
+
 RE_SANITIZE_FILENAME = re.compile(r'(~|\.\.|/|\\)')
 RE_SANITIZE_PATH = re.compile(r'(~|\.(\.)+)')
 RE_SLUGIFY = re.compile(r'[^A-Za-z0-9_]+')
 
-DATE_STR_FORMAT = "%H:%M:%S %d-%m-%Y"
-
 
 def sanitize_filename(filename):
     """ Sanitizes a filename by removing .. / and \\. """
@@ -42,33 +47,6 @@ def slugify(text):
     return RE_SLUGIFY.sub("", text)
 
 
-def datetime_to_str(dattim):
-    """ Converts datetime to a string format.
-
-    @rtype : str
-    """
-    return dattim.strftime(DATE_STR_FORMAT)
-
-
-def str_to_datetime(dt_str):
-    """ Converts a string to a datetime object.
-
-    @rtype: datetime
-    """
-    try:
-        return datetime.strptime(dt_str, DATE_STR_FORMAT)
-    except ValueError:  # If dt_str did not match our format
-        return None
-
-
-def strip_microseconds(dattim):
-    """ Returns a copy of dattime object but with microsecond set to 0. """
-    if dattim.microsecond:
-        return dattim - timedelta(microseconds=dattim.microsecond)
-    else:
-        return dattim
-
-
 def split_entity_id(entity_id):
     """ Splits a state entity_id into domain, object_id. """
     return entity_id.split(".", 1)
@@ -81,7 +59,7 @@ def repr_helper(inp):
             repr_helper(key)+"="+repr_helper(item) for key, item
             in inp.items())
     elif isinstance(inp, datetime):
-        return datetime_to_str(inp)
+        return datetime_to_local_str(inp)
     else:
         return str(inp)
 
@@ -464,7 +442,7 @@ class ThreadPool(object):
                 return
 
             # Add to current running jobs
-            job_log = (datetime.now(), job)
+            job_log = (utcnow(), job)
             self.current_jobs.append(job_log)
 
             # Do the job
diff --git a/homeassistant/util/dt.py b/homeassistant/util/dt.py
new file mode 100644
index 00000000000..c0e695bbb0c
--- /dev/null
+++ b/homeassistant/util/dt.py
@@ -0,0 +1,99 @@
+"""
+homeassistant.util.dt
+~~~~~~~~~~~~~~~~~~~~~
+
+Provides helper methods to handle the time in HA.
+
+"""
+import datetime as dt
+
+import pytz
+
+DATE_STR_FORMAT = "%H:%M:%S %d-%m-%Y"
+UTC = DEFAULT_TIME_ZONE = pytz.utc
+
+
+def set_default_time_zone(time_zone):
+    """ Sets a default time zone to be used when none is specified. """
+    global DEFAULT_TIME_ZONE  # pylint: disable=global-statement
+
+    assert isinstance(time_zone, dt.tzinfo)
+
+    DEFAULT_TIME_ZONE = time_zone
+
+
+def get_time_zone(time_zone_str):
+    """ Get time zone from string. Return None if unable to determine. """
+    try:
+        return pytz.timezone(time_zone_str)
+    except pytz.exceptions.UnknownTimeZoneError:
+        return None
+
+
+def utcnow():
+    """ Get now in UTC time. """
+    return dt.datetime.utcnow().replace(tzinfo=pytz.utc)
+
+
+def now(time_zone=None):
+    """ Get now in specified time zone. """
+    if time_zone is None:
+        time_zone = DEFAULT_TIME_ZONE
+
+    return utcnow().astimezone(time_zone)
+
+
+def as_utc(dattim):
+    """ Return a datetime as UTC time.
+        Assumes datetime without tzinfo to be in the DEFAULT_TIME_ZONE. """
+    if dattim.tzinfo == pytz.utc:
+        return dattim
+    elif dattim.tzinfo is None:
+        dattim = dattim.replace(tzinfo=DEFAULT_TIME_ZONE)
+
+    return dattim.astimezone(pytz.utc)
+
+
+def as_local(dattim):
+    """ Converts a UTC datetime object to local time_zone. """
+    if dattim.tzinfo == DEFAULT_TIME_ZONE:
+        return dattim
+    elif dattim.tzinfo is None:
+        dattim = dattim.replace(tzinfo=pytz.utc)
+
+    return dattim.astimezone(DEFAULT_TIME_ZONE)
+
+
+def utc_from_timestamp(timestamp):
+    """ Returns a UTC time from a timestamp. """
+    return dt.datetime.fromtimestamp(timestamp, pytz.utc)
+
+
+def datetime_to_local_str(dattim, time_zone=None):
+    """ Converts datetime to specified time_zone and returns a string. """
+    return datetime_to_str(as_local(dattim))
+
+
+def datetime_to_str(dattim):
+    """ Converts datetime to a string format.
+
+    @rtype : str
+    """
+    return dattim.strftime(DATE_STR_FORMAT)
+
+
+def str_to_datetime(dt_str):
+    """ Converts a string to a UTC datetime object.
+
+    @rtype: datetime
+    """
+    try:
+        return dt.datetime.strptime(
+            dt_str, DATE_STR_FORMAT).replace(tzinfo=pytz.utc)
+    except ValueError:  # If dt_str did not match our format
+        return None
+
+
+def strip_microseconds(dattim):
+    """ Returns a copy of dattime object but with microsecond set to 0. """
+    return dattim.replace(microsecond=0)
diff --git a/requirements.txt b/requirements.txt
index e1b0a942f80..59a1c3ea39a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,7 @@
 # required for Home Assistant core
 requests>=2.0
 pyyaml>=3.11
+pytz>=2015.2
 
 # optional, needed for specific components
 
diff --git a/scripts/run_tests b/scripts/run_tests
index 8d1c6aed114..75b25ca805a 100755
--- a/scripts/run_tests
+++ b/scripts/run_tests
@@ -3,4 +3,8 @@ if [ ${PWD##*/} == "scripts" ]; then
     cd ..
 fi
 
-python3 -m unittest discover tests
+if [ "$1" = "coverage" ]; then
+  coverage run -m unittest discover tests
+else
+  python3 -m unittest discover tests
+fi
diff --git a/tests/test_component_device_scanner.py b/tests/test_component_device_tracker.py
similarity index 97%
rename from tests/test_component_device_scanner.py
rename to tests/test_component_device_tracker.py
index 2bd392c21d0..74af55fdc66 100644
--- a/tests/test_component_device_scanner.py
+++ b/tests/test_component_device_tracker.py
@@ -1,17 +1,18 @@
 """
-tests.test_component_group
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+tests.test_component_device_tracker
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Tests the group compoments.
+Tests the device tracker compoments.
 """
 # pylint: disable=protected-access,too-many-public-methods
 import unittest
-from datetime import datetime, timedelta
+from datetime import timedelta
 import logging
 import os
 
 import homeassistant as ha
 import homeassistant.loader as loader
+import homeassistant.util.dt as dt_util
 from homeassistant.const import (
     STATE_HOME, STATE_NOT_HOME, ATTR_ENTITY_PICTURE, CONF_PLATFORM)
 import homeassistant.components.device_tracker as device_tracker
@@ -116,7 +117,7 @@ class TestComponentsDeviceTracker(unittest.TestCase):
         dev2 = device_tracker.ENTITY_ID_FORMAT.format('device_2')
         dev3 = device_tracker.ENTITY_ID_FORMAT.format('DEV3')
 
-        now = datetime.now()
+        now = dt_util.utcnow()
 
         # Device scanner scans every 12 seconds. We need to sync our times to
         # be every 12 seconds or else the time_changed event will be ignored.
diff --git a/tests/test_component_sun.py b/tests/test_component_sun.py
index a4ff19429f3..aec97ede6a8 100644
--- a/tests/test_component_sun.py
+++ b/tests/test_component_sun.py
@@ -6,11 +6,12 @@ Tests Sun component.
 """
 # pylint: disable=too-many-public-methods,protected-access
 import unittest
-import datetime as dt
+from datetime import timedelta
 
 import ephem
 
 import homeassistant as ha
+import homeassistant.util.dt as dt_util
 import homeassistant.components.sun as sun
 
 
@@ -42,22 +43,20 @@ class TestSun(unittest.TestCase):
         observer.lat = '32.87336'  # pylint: disable=assigning-non-slot
         observer.long = '117.22743'  # pylint: disable=assigning-non-slot
 
-        utc_now = dt.datetime.utcnow()
+        utc_now = dt_util.utcnow()
         body_sun = ephem.Sun()  # pylint: disable=no-member
-        next_rising_dt = ephem.localtime(
-            observer.next_rising(body_sun, start=utc_now))
-        next_setting_dt = ephem.localtime(
-            observer.next_setting(body_sun, start=utc_now))
+        next_rising_dt = observer.next_rising(
+            body_sun, start=utc_now).datetime().replace(tzinfo=dt_util.UTC)
+        next_setting_dt = observer.next_setting(
+            body_sun, start=utc_now).datetime().replace(tzinfo=dt_util.UTC)
 
         # Home Assistant strips out microseconds
         # strip it out of the datetime objects
-        next_rising_dt = next_rising_dt - dt.timedelta(
-            microseconds=next_rising_dt.microsecond)
-        next_setting_dt = next_setting_dt - dt.timedelta(
-            microseconds=next_setting_dt.microsecond)
+        next_rising_dt = dt_util.strip_microseconds(next_rising_dt)
+        next_setting_dt = dt_util.strip_microseconds(next_setting_dt)
 
-        self.assertEqual(next_rising_dt, sun.next_rising(self.hass))
-        self.assertEqual(next_setting_dt, sun.next_setting(self.hass))
+        self.assertEqual(next_rising_dt, sun.next_rising_utc(self.hass))
+        self.assertEqual(next_setting_dt, sun.next_setting_utc(self.hass))
 
         # Point it at a state without the proper attributes
         self.hass.states.set(sun.ENTITY_ID, sun.STATE_ABOVE_HORIZON)
@@ -84,7 +83,7 @@ class TestSun(unittest.TestCase):
         self.assertIsNotNone(test_time)
 
         self.hass.bus.fire(ha.EVENT_TIME_CHANGED,
-                           {ha.ATTR_NOW: test_time + dt.timedelta(seconds=5)})
+                           {ha.ATTR_NOW: test_time + timedelta(seconds=5)})
 
         self.hass.pool.block_till_done()
 
diff --git a/tests/test_core.py b/tests/test_core.py
index a5c37f753b9..b450479f2d9 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -72,7 +72,7 @@ class TestHomeAssistant(unittest.TestCase):
 
         runs = []
 
-        self.hass.track_point_in_time(
+        self.hass.track_point_in_utc_time(
             lambda x: runs.append(1), birthday_paulus)
 
         self._send_time_changed(before_birthday)
@@ -88,7 +88,7 @@ class TestHomeAssistant(unittest.TestCase):
         self.hass.pool.block_till_done()
         self.assertEqual(1, len(runs))
 
-        self.hass.track_point_in_time(
+        self.hass.track_point_in_utc_time(
             lambda x: runs.append(1), birthday_paulus)
 
         self._send_time_changed(after_birthday)
diff --git a/tests/test_util.py b/tests/test_util.py
index 038db227e1a..f75b6db8aeb 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -35,17 +35,6 @@ class TestUtil(unittest.TestCase):
         self.assertEqual("Test_More", util.slugify("Test More"))
         self.assertEqual("Test_More", util.slugify("Test_(More)"))
 
-    def test_datetime_to_str(self):
-        """ Test datetime_to_str. """
-        self.assertEqual("12:00:00 09-07-1986",
-                         util.datetime_to_str(datetime(1986, 7, 9, 12, 0, 0)))
-
-    def test_str_to_datetime(self):
-        """ Test str_to_datetime. """
-        self.assertEqual(datetime(1986, 7, 9, 12, 0, 0),
-                         util.str_to_datetime("12:00:00 09-07-1986"))
-        self.assertIsNone(util.str_to_datetime("not a datetime string"))
-
     def test_split_entity_id(self):
         """ Test split_entity_id. """
         self.assertEqual(['domain', 'object_id'],
diff --git a/tests/test_util_dt.py b/tests/test_util_dt.py
new file mode 100644
index 00000000000..5deafb58040
--- /dev/null
+++ b/tests/test_util_dt.py
@@ -0,0 +1,137 @@
+"""
+tests.test_util
+~~~~~~~~~~~~~~~~~
+
+Tests Home Assistant date util methods.
+"""
+# pylint: disable=too-many-public-methods
+import unittest
+from datetime import datetime, timedelta
+
+import homeassistant.util.dt as dt_util
+
+TEST_TIME_ZONE = 'America/Los_Angeles'
+
+
+class TestDateUtil(unittest.TestCase):
+    """ Tests util date methods. """
+
+    def setUp(self):
+        self.orig_default_time_zone = dt_util.DEFAULT_TIME_ZONE
+
+    def tearDown(self):
+        dt_util.set_default_time_zone(self.orig_default_time_zone)
+
+    def test_get_time_zone_retrieves_valid_time_zone(self):
+        """ Test getting a time zone. """
+        time_zone = dt_util.get_time_zone(TEST_TIME_ZONE)
+
+        self.assertIsNotNone(time_zone)
+        self.assertEqual(TEST_TIME_ZONE, time_zone.zone)
+
+    def test_get_time_zone_returns_none_for_garbage_time_zone(self):
+        """ Test getting a non existing time zone. """
+        time_zone = dt_util.get_time_zone("Non existing time zone")
+
+        self.assertIsNone(time_zone)
+
+    def test_set_default_time_zone(self):
+        """ Test setting default time zone. """
+        time_zone = dt_util.get_time_zone(TEST_TIME_ZONE)
+
+        dt_util.set_default_time_zone(time_zone)
+
+        # We cannot compare the timezones directly because of DST
+        self.assertEqual(time_zone.zone, dt_util.now().tzinfo.zone)
+
+    def test_utcnow(self):
+        """ Test the UTC now method. """
+        self.assertAlmostEqual(
+            dt_util.utcnow().replace(tzinfo=None),
+            datetime.utcnow(),
+            delta=timedelta(seconds=1))
+
+    def test_now(self):
+        """ Test the now method. """
+        dt_util.set_default_time_zone(dt_util.get_time_zone(TEST_TIME_ZONE))
+
+        self.assertAlmostEqual(
+            dt_util.as_utc(dt_util.now()).replace(tzinfo=None),
+            datetime.utcnow(),
+            delta=timedelta(seconds=1))
+
+    def test_as_utc_with_naive_object(self):
+        utcnow = datetime.utcnow()
+
+        self.assertEqual(utcnow,
+                         dt_util.as_utc(utcnow).replace(tzinfo=None))
+
+    def test_as_utc_with_utc_object(self):
+        utcnow = dt_util.utcnow()
+
+        self.assertEqual(utcnow, dt_util.as_utc(utcnow))
+
+    def test_as_utc_with_local_object(self):
+        dt_util.set_default_time_zone(dt_util.get_time_zone(TEST_TIME_ZONE))
+
+        localnow = dt_util.now()
+
+        utcnow = dt_util.as_utc(localnow)
+
+        self.assertEqual(localnow, utcnow)
+        self.assertNotEqual(localnow.tzinfo, utcnow.tzinfo)
+
+    def test_as_local_with_naive_object(self):
+        now = dt_util.now()
+
+        self.assertAlmostEqual(
+            now, dt_util.as_local(datetime.utcnow()),
+            delta=timedelta(seconds=1))
+
+    def test_as_local_with_local_object(self):
+        now = dt_util.now()
+
+        self.assertEqual(now, now)
+
+    def test_as_local_with_utc_object(self):
+        dt_util.set_default_time_zone(dt_util.get_time_zone(TEST_TIME_ZONE))
+
+        utcnow = dt_util.utcnow()
+        localnow = dt_util.as_local(utcnow)
+
+        self.assertEqual(localnow, utcnow)
+        self.assertNotEqual(localnow.tzinfo, utcnow.tzinfo)
+
+    def test_utc_from_timestamp(self):
+        """ Test utc_from_timestamp method. """
+        self.assertEqual(
+            datetime(1986, 7, 9, tzinfo=dt_util.UTC),
+            dt_util.utc_from_timestamp(521251200))
+
+    def test_datetime_to_str(self):
+        """ Test datetime_to_str. """
+        self.assertEqual(
+            "12:00:00 09-07-1986",
+            dt_util.datetime_to_str(datetime(1986, 7, 9, 12, 0, 0)))
+
+    def test_datetime_to_local_str(self):
+        """ Test datetime_to_local_str. """
+        self.assertEqual(
+            dt_util.datetime_to_str(dt_util.now()),
+            dt_util.datetime_to_local_str(dt_util.utcnow()))
+
+    def test_str_to_datetime_converts_correctly(self):
+        """ Test str_to_datetime converts strings. """
+        self.assertEqual(
+            datetime(1986, 7, 9, 12, 0, 0, tzinfo=dt_util.UTC),
+            dt_util.str_to_datetime("12:00:00 09-07-1986"))
+
+    def test_str_to_datetime_returns_none_for_incorrect_format(self):
+        """ Test str_to_datetime returns None if incorrect format. """
+        self.assertIsNone(dt_util.str_to_datetime("not a datetime string"))
+
+    def test_strip_microseconds(self):
+        test_time = datetime(2015, 1, 1, microsecond=5000)
+
+        self.assertNotEqual(0, test_time.microsecond)
+        self.assertEqual(0, dt_util.strip_microseconds(test_time).microsecond)