diff --git a/cea/constants.py b/cea/constants.py
index a11f184aa8..5e07f0294f 100644
--- a/cea/constants.py
+++ b/cea/constants.py
@@ -5,6 +5,7 @@
 declare the constants closest to the point of usage.
 """
 from __future__ import absolute_import
+
 __author__ = "Sreepathi Bhargava Krishna"
 __copyright__ = "Copyright 2017, Architecture and Building Systems - ETH Zurich"
 __credits__ = ["Sreepathi Bhargava Krishna"]
@@ -28,6 +29,8 @@
 HOURS_IN_DAY = 24
 HOURS_IN_YEAR = 8760
 MONTHS_IN_YEAR = 12
+HOURS_PRE_CONDITIONING = 720  # number of hours that the building will be thermally pre-conditioned,
+                                # the results of these hours will be overwritten
 
 # Specific heat
 HEAT_CAPACITY_OF_WATER_JPERKGK = 4185  # [J/kg K]
diff --git a/cea/databases/CH/archetypes/construction_properties.xlsx b/cea/databases/CH/archetypes/construction_properties.xlsx
index e11527e335..5288751a38 100644
Binary files a/cea/databases/CH/archetypes/construction_properties.xlsx and b/cea/databases/CH/archetypes/construction_properties.xlsx differ
diff --git a/cea/demand/constants.py b/cea/demand/constants.py
index 048e0a80e5..1a74eda51f 100644
--- a/cea/demand/constants.py
+++ b/cea/demand/constants.py
@@ -28,7 +28,7 @@
 P_FAN = 0.55  # specific fan consumption in W/m3/h
 MIN_VENTILATION_RATE = 0.6  # l/s/m2 [https://escholarship.org/content/qt7k1796zv/qt7k1796zv.pdf]
 TEMPERATURE_ZONE_CONTROL_NIGHT_FLUSHING = 26  # (°C) night flushing only if temperature is higher than 26 # TODO review and make dynamic
-DELTA_T_NIGHT_FLUSHING = 2  # (°C) night flushing only if outdoor temperature is two degrees lower than indoor # TODO review and make dynamic
+DELTA_T_NIGHT_FLUSHING = 2  # (°C) night flushing only if outdoor temperature is two degrees lower than indoor according to SIA 382/1
 SHIELDING_CLASS = 2  # according to ISO 16798-7, 0 = open terrain, 1 = partly shielded from wind,
         #  2 = fully shielded from wind
 TER_CLASS = 2  # terrain class of surroundings according to ISO 16798-7: 0 = open, 1 = rural,  2 = urban
diff --git a/cea/demand/control_ventilation_systems.py b/cea/demand/control_ventilation_systems.py
index 0ef4f7a712..35e14234cb 100644
--- a/cea/demand/control_ventilation_systems.py
+++ b/cea/demand/control_ventilation_systems.py
@@ -70,10 +70,10 @@ def is_mechanical_ventilation_heat_recovery_active(bpr, tsd, t):
     if is_mechanical_ventilation_active(bpr, tsd, t)\
             and has_mechanical_ventilation_heat_recovery(bpr)\
             and control_heating_cooling_systems.is_heating_season(t, bpr):
-
-        # heat recovery is always active if mechanical ventilation is active (no intelligent by pass)
-        # this is the usual system configuration according to Clayton Miller
-        return True
+        if is_night_flushing_active(bpr, tsd, t) or is_economizer_active(bpr, tsd, t):
+            return False
+        else:
+            return True
 
     elif is_mechanical_ventilation_active(bpr, tsd, t)\
             and has_mechanical_ventilation_heat_recovery(bpr)\
@@ -87,7 +87,7 @@ def is_mechanical_ventilation_heat_recovery_active(bpr, tsd, t):
             and tsd['T_int'][t-1] >= tsd['T_ext'][t]:
 
         # heat recovery is deactivated in the cooling case,
-        #  if outdoor air conditions are colder than indoor (free cooling)
+        # if outdoor air conditions are colder than indoor (free cooling)
 
         return False
 
@@ -98,10 +98,9 @@ def is_mechanical_ventilation_heat_recovery_active(bpr, tsd, t):
 def is_night_flushing_active(bpr, tsd, t):
 
     # night flushing is available for window ventilation (manual) and mechanical ventilation (automatic)
-    # night flushing is active during the night in the cooling season, if the outdoor conditions are favourable
+    # night flushing is active during the night if the outdoor conditions are favourable
 
     if has_night_flushing(bpr) \
-            and control_heating_cooling_systems.is_cooling_season(t, bpr) \
             and is_night_time(t) \
             and tsd['T_int'][t-1] > TEMPERATURE_ZONE_CONTROL_NIGHT_FLUSHING \
             and tsd['T_int'][t-1] > tsd['T_ext'][t] + DELTA_T_NIGHT_FLUSHING \
@@ -118,8 +117,8 @@ def is_economizer_active(bpr, tsd, t):
     Control of activity of economizer of mechanical ventilation system
     Economizer of mechanical ventilation is controlled via zone set point temperatures, indoor air temperature and
     outdoor air temperature.
-    Economizer is active during cooling season if the indoor air temperature exceeds the set point and the outdoor
-    temperatures are lower than the set point.
+    Economizer is active if the indoor air temperature exceeds the set point and the outdoor temperatures are lower
+    than the set point.
     Economizer increases mechanical ventilation flow rate to the maximum.
     
     Author: Gabriel Happle
@@ -136,8 +135,7 @@ def is_economizer_active(bpr, tsd, t):
     """
 
     if has_mechanical_ventilation_economizer(bpr) \
-            and control_heating_cooling_systems.is_cooling_season(t, bpr) \
-            and tsd['T_int'][t-1] > tsd['ta_cs_set'][t] >= tsd['T_ext'][t]:
+            and tsd['T_int'][t-1] > bpr.comfort['Tcs_set_C'] >= tsd['T_ext'][t]:
 
         return True
 
diff --git a/cea/demand/demand_main.py b/cea/demand/demand_main.py
index 986e2fe66a..0dc998d199 100644
--- a/cea/demand/demand_main.py
+++ b/cea/demand/demand_main.py
@@ -99,8 +99,7 @@ def calc_buildings_less_100m2(building_properties):
 
     list_buildings_less_100m2 = calc_buildings_less_100m2(building_properties)
     if list_buildings_less_100m2 != []:
-        print(
-                    'Warning! The following list of buildings have less than 100 m2 of gross floor area, CEA might fail: %s' % list_buildings_less_100m2)
+        print('Warning! The following list of buildings have less than 100 m2 of gross floor area, CEA might fail: %s' % list_buildings_less_100m2)
 
     # SPECIFY NUMBER OF BUILDINGS TO SIMULATE
     if not building_names:
diff --git a/cea/demand/hourly_procedure_heating_cooling_system_load.py b/cea/demand/hourly_procedure_heating_cooling_system_load.py
index 3e6f944451..395ac97628 100644
--- a/cea/demand/hourly_procedure_heating_cooling_system_load.py
+++ b/cea/demand/hourly_procedure_heating_cooling_system_load.py
@@ -63,7 +63,7 @@ def calc_heating_cooling_loads(bpr, tsd, t):
 
         else:
             # message and no heating system
-            warnings.warn('Unknown cooling system. Calculation without system.')
+            warnings.warn('Unknown heating system. Calculation without system.')
 
             # no system = no loads
             rc_model_temperatures = calc_rc_no_loads(bpr, tsd, t)
diff --git a/cea/demand/schedule_maker/schedule_maker.py b/cea/demand/schedule_maker/schedule_maker.py
index 55f878bed4..3ed1384be6 100644
--- a/cea/demand/schedule_maker/schedule_maker.py
+++ b/cea/demand/schedule_maker/schedule_maker.py
@@ -45,7 +45,7 @@ def schedule_maker_main(locator, config, building=None):
 
     if buildings == []:
         buildings = locator.get_zone_building_names()
-    if building !=None:
+    if building != None:
         buildings = [building] #this is to run the tests
 
     # get variables of indoor comfort and internal loads
diff --git a/cea/demand/thermal_loads.py b/cea/demand/thermal_loads.py
index e00ef1a94b..ad3023f687 100644
--- a/cea/demand/thermal_loads.py
+++ b/cea/demand/thermal_loads.py
@@ -5,7 +5,7 @@
 from __future__ import division
 
 import numpy as np
-from cea.constants import HOURS_IN_YEAR
+from cea.constants import HOURS_IN_YEAR, HOURS_PRE_CONDITIONING
 import pandas as pd
 from cea.demand.latent_loads import convert_rh_to_moisture_content
 from cea.demand import demand_writers
@@ -86,14 +86,14 @@ def calc_thermal_loads(building_name, bpr, weather_data, date_range, locator,
 
     if np.isclose(bpr.rc_model['Af'], 0.0):  # if building does not have conditioned area
         tsd['T_int'] = tsd['T_ext']
-        tsd['x_int'] = np.vectorize(convert_rh_to_moisture_content)(tsd['rh_ext'] , tsd['T_int'])
-        print("building () does not have an air-conditioned area").format(bpr.name)
+        tsd['x_int'] = np.vectorize(convert_rh_to_moisture_content)(tsd['rh_ext'], tsd['T_int'])
+        print("building () does not have an air-conditioned area".format(bpr.name))
     else:
 
-        #CALCULATE PROCESS HEATING
+        # CALCULATE PROCESS HEATING
         tsd['Qhpro_sys'] = schedules['Qhpro_W']  # in Wh
 
-        #CALCULATE PROCESS COOLING
+        # CALCULATE PROCESS COOLING
         tsd['Qcpro_sys'] = schedules['Qcpro_W']   # in Wh
 
         # CALCULATE DATA CENTER LOADS
@@ -150,7 +150,7 @@ def calc_thermal_loads(building_name, bpr, weather_data, date_range, locator,
     tsd = electrical_loads.calc_E_sys(tsd)  # system (incl. losses)
     tsd = electrical_loads.calc_Ef(bpr, tsd)  # final (incl. self. generated)
 
-    #WRITE SOLAR RESULTS
+    # WRITE SOLAR RESULTS
     write_results(bpr, building_name, date_range, loads_output, locator, massflows_output,
                   resolution_outputs, temperatures_output, tsd, debug)
 
@@ -158,10 +158,10 @@ def calc_thermal_loads(building_name, bpr, weather_data, date_range, locator,
 
 
 def calc_QH_sys_QC_sys(tsd):
-  tsd['QH_sys'] = tsd['Qww_sys'] + tsd['Qhs_sys'] + tsd['Qhpro_sys']
-  tsd['QC_sys'] = tsd['Qcs_sys'] + tsd['Qcdata_sys'] + tsd['Qcre_sys'] + tsd['Qcpro_sys']
+    tsd['QH_sys'] = tsd['Qww_sys'] + tsd['Qhs_sys'] + tsd['Qhpro_sys']
+    tsd['QC_sys'] = tsd['Qcs_sys'] + tsd['Qcdata_sys'] + tsd['Qcre_sys'] + tsd['Qcpro_sys']
 
-  return tsd
+    return tsd
 
 
 def write_results(bpr, building_name, date, loads_output, locator, massflows_output,
@@ -397,7 +397,7 @@ def initialize_inputs(bpr, weather_data, locator):
     occupancy_yearly_schedules = pd.read_csv(locator.get_schedule_model_file(building_name))
 
     tsd['people'] = occupancy_yearly_schedules['people_pax']
-    tsd['ve'] = occupancy_yearly_schedules['Ve_lps'] * 3.6 #m3/h
+    tsd['ve'] = occupancy_yearly_schedules['Ve_lps'] * 3.6  # m3/h
     tsd['Qs'] = occupancy_yearly_schedules['Qs_W']
 
     return occupancy_yearly_schedules, tsd
@@ -587,10 +587,6 @@ def update_timestep_data_no_conditioned_area(tsd):
     return tsd
 
 
-HOURS_IN_YEAR = HOURS_IN_YEAR
-HOURS_PRE_CONDITIONING = 720  # number of hours that the building will be thermally pre-conditioned, the results of these hours will be overwritten
-
-
 def get_hours(bpr):
     """
 
diff --git a/cea/tests/create_unittest_data.py b/cea/tests/create_unittest_data.py
index f1327649f0..8f4501b864 100644
--- a/cea/tests/create_unittest_data.py
+++ b/cea/tests/create_unittest_data.py
@@ -52,7 +52,7 @@ def main(output_file):
     print("data for test_calc_thermal_loads:")
     print(building_properties.list_building_names())
 
-    schedule_maker_main(locator, config, building='B01')
+    schedule_maker_main(locator, config, building=None)
 
     bpr = building_properties['B01']
     result = calc_thermal_loads('B01', bpr, weather_data, date_range, locator,
diff --git a/cea/tests/test_calc_thermal_loads.config b/cea/tests/test_calc_thermal_loads.config
index ea789eb530..a06427a688 100644
--- a/cea/tests/test_calc_thermal_loads.config
+++ b/cea/tests/test_calc_thermal_loads.config
@@ -3,5 +3,5 @@ value_columns = ["E_sys_kWh", "Qcdata_sys_kWh", "Qcre_sys_kWh", "Qcs_sys_kWh", "
 values = [397332.706, 0.0, 0.0, 54493.56, 96284.527, 19784.978, 0.0, 0.0, 26186.16, 0.0, 0.0, 171600.0]
 
 [test_calc_thermal_loads_other_buildings]
-results = {"B01": [96284.527, 54493.56, 19784.978], "B03": [60941.42700000001, 101654.203, 117381.388], "B02": [299345.566, 25872.039, 312647.82999999996], "B05": [127871.16, 0.0, 73559.536], "B04": [153030.22400000002, 36521.226, 17519.388000000003], "B07": [158362.75199999998, 49693.31, 31347.407], "B06": [66017.055, 79389.545, 168321.332], "B09": [136263.101, 18328.773999999998, 15160.633999999998], "B08": [164834.07100000003, 29106.078999999998, 400109.881]}
+results = {"B01": [96284.527, 54493.56, 19784.978], "B03": [61270.984, 103288.264, 117428.537], "B02": [299345.566, 25872.039, 312647.82999999996], "B05": [127871.16, 0.0, 73559.536], "B04": [153030.22400000002, 36404.417, 17519.653000000002], "B07": [158375.001, 46013.644, 31350.313], "B06": [66140.078, 80270.72899999999, 168329.153], "B09": [136263.101, 18254.959000000003, 15161.161], "B08": [164841.764, 27644.819, 400112.534]}