diff --git a/city_model_structure/energy_system.py b/city_model_structure/energy_system.py
index 04ab3681..f1815bac 100644
--- a/city_model_structure/energy_system.py
+++ b/city_model_structure/energy_system.py
@@ -6,7 +6,8 @@ Contributor Peter Yefi peteryefi@gmail.com
 """
 
 from city_model_structure.city_object import CityObject
-from city_model_structure.energy_systems.heat_pump import HeatPump
+from city_model_structure.energy_systems.air_source_hp import AirSourceHP
+from city_model_structure.energy_systems.water_to_water_hp import WaterToWaterHP
 
 
 class EnergySystem(CityObject):
@@ -16,25 +17,43 @@ class EnergySystem(CityObject):
 
     def __init__(self, name, lod, surfaces, city_lower_corner):
         super().__init__(name, lod, surfaces, city_lower_corner)
-        self._heat_pump = None
+        self._air_source_hp = None
+        self._water_to_water_hp = None
         self._type = 'energy_system'
 
     @property
-    def heat_pump(self) -> HeatPump:
+    def air_source_hp(self) -> AirSourceHP:
         """
         Heat pump energy system
         :return:
         """
-        return self._heat_pump
+        return self._air_source_hp
 
-    @heat_pump.setter
-    def heat_pump(self, value):
+    @air_source_hp.setter
+    def air_source_hp(self, value):
         """
-        Set heat pumm for energy system
-        :param value: HeatPump
+        Set heat pump for energy system
+        :param value: AirSourceHP
         """
-        if self._heat_pump is None:
-            self._heat_pump = value
+        if self._air_source_hp is None:
+            self._air_source_hp = value
+
+    @property
+    def water_to_water_hp(self) -> WaterToWaterHP:
+        """
+        Water to water heat pump energy system
+        :return:
+        """
+        return self._water_to_water_hp
+
+    @water_to_water_hp.setter
+    def water_to_water_hp(self, value):
+        """
+        Set water to water heat pump for energy system
+        :param value: WaterToWaterHP
+        """
+        if self._water_to_water_hp is None:
+            self._water_to_water_hp = value
 
     @property
     def type(self) -> str:
diff --git a/city_model_structure/energy_systems/air_source_hp.py b/city_model_structure/energy_systems/air_source_hp.py
new file mode 100644
index 00000000..752f13b0
--- /dev/null
+++ b/city_model_structure/energy_systems/air_source_hp.py
@@ -0,0 +1,190 @@
+"""
+heat_pump module defines a heat pump
+SPDX - License - Identifier: LGPL - 3.0 - or -later
+Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
+Contributor Peter Yefi peteryefi@gmail.com
+"""
+
+from typing import List
+from typing import Dict
+
+
+class HeatPump:
+  """
+  HeatPump class
+  """
+
+  def __init__(self):
+    self._model = None
+    self._cooling_capacity = None
+    self._cooling_comp_power = None
+    self._cooling_capacity_coff = None
+    self._cooling_comp_power_coff = None
+    self._heating_capacity = None
+    self._heating_comp_power = None
+    self._heating_capacity_coff = None
+    self._heating_comp_power_coff = None
+
+  @property
+  def model(self) -> str:
+    """
+    Get model name
+    :return: str
+    """
+    return self._model
+
+  @model.setter
+  def model(self, value):
+    """
+    Set model (name, indicated in capacity)
+    :param value: str
+    """
+    if self._model is None:
+      self._model = value
+
+  @property
+  def cooling_capacity(self) -> List[float]:
+    """
+    Get cooling capacity in kW
+    :return: [[float]]
+    """
+    return self._cooling_capacity
+
+  @cooling_capacity.setter
+  def cooling_capacity(self, value):
+    """
+    Set cooling capacity in kW
+    :param value: [[float]]
+    """
+    if self._cooling_capacity is None:
+      self._cooling_capacity = value
+
+  @property
+  def cooling_comp_power(self) -> List[float]:
+    """
+    Get cooling compressor power input in kW
+    :return: [[float]]
+    """
+    return self._cooling_comp_power
+
+  @cooling_comp_power.setter
+  def cooling_comp_power(self, value):
+    """
+    Set the cooling compressor in kW
+    :param value: [[float]]
+    :return:
+    """
+    if self._cooling_comp_power is None:
+      self._cooling_comp_power = value
+
+  @property
+  def cooling_capacity_coff(self) -> List[float]:
+    """
+    Get cooling capacity coefficients
+    :return: [float]
+    """
+    return self._cooling_capacity_coff
+
+  @cooling_capacity_coff.setter
+  def cooling_capacity_coff(self, value):
+    """
+    Set the value for cooling capacity coefficients
+    :param value: [float]
+    :return:
+    """
+    if self._cooling_capacity_coff is None:
+      self._cooling_capacity_coff = value
+
+  @property
+  def cooling_comp_power_coff(self) -> List[float]:
+    """
+    Get cooling compressor power coefficients
+    :return: [float]
+    """
+    return self._cooling_comp_power_coff
+
+  @cooling_comp_power_coff.setter
+  def cooling_comp_power_coff(self, value):
+    """
+    Set the value for cooling compressor power coefficients
+    :param value: [float]
+    :return:
+    """
+    if self._cooling_comp_power_coff is None:
+      self._cooling_comp_power_coff = value
+
+
+
+  @property
+  def heating_capacity(self) -> List[float]:
+    """
+    Get heating capacity kW
+    :return: [[float]]
+    """
+    return self._heating_capacity
+
+  @heating_capacity.setter
+  def heating_capacity(self, value):
+    """
+    Set the heating capacity in kW
+    :param value: [[float]]
+    :return:
+    """
+    if self._heating_capacity is None:
+      self._heating_capacity = value
+
+  @property
+  def heating_comp_power(self) -> List[float]:
+    """
+    Get heating compressor power kW
+    :return: [[float]]
+    """
+    return self._heating_comp_power
+
+  @heating_comp_power.setter
+  def heating_comp_power(self, value):
+    """
+    Set the heating compressor power in kW
+    :param value: [[float]]
+    :return:
+    """
+    if self._heating_comp_power is None:
+      self._heating_comp_power = value
+
+  @property
+  def heating_comp_power_coff(self) -> List[float]:
+    """
+    Get heating compressor power coefficients
+    :return: [float]
+    """
+    return self._heating_comp_power_coff
+
+  @heating_comp_power_coff.setter
+  def heating_comp_power_coff(self, value):
+    """
+    Set the value for heating compressor power coefficients
+    :param value: [float]
+    :return:
+    """
+    if self._heating_comp_power_coff is None:
+      self._heating_comp_power_coff = value
+
+  @property
+  def heating_capacity_coff(self) -> List[float]:
+    """
+    Get heating capacity coefficients
+    :return: [float]
+    """
+    return self._heating_capacity_coff
+
+  @heating_capacity_coff.setter
+  def heating_capacity_coff(self, value):
+    """
+    Set the value for heating capacity coefficients
+    :param value: [float]
+    :return:
+    """
+    if self._heating_capacity_coff is None:
+      self._heating_capacity_coff = value
+
+
diff --git a/city_model_structure/energy_systems/heat_pump.py b/city_model_structure/energy_systems/heat_pump.py
index 752f13b0..e69de29b 100644
--- a/city_model_structure/energy_systems/heat_pump.py
+++ b/city_model_structure/energy_systems/heat_pump.py
@@ -1,190 +0,0 @@
-"""
-heat_pump module defines a heat pump
-SPDX - License - Identifier: LGPL - 3.0 - or -later
-Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
-Contributor Peter Yefi peteryefi@gmail.com
-"""
-
-from typing import List
-from typing import Dict
-
-
-class HeatPump:
-  """
-  HeatPump class
-  """
-
-  def __init__(self):
-    self._model = None
-    self._cooling_capacity = None
-    self._cooling_comp_power = None
-    self._cooling_capacity_coff = None
-    self._cooling_comp_power_coff = None
-    self._heating_capacity = None
-    self._heating_comp_power = None
-    self._heating_capacity_coff = None
-    self._heating_comp_power_coff = None
-
-  @property
-  def model(self) -> str:
-    """
-    Get model name
-    :return: str
-    """
-    return self._model
-
-  @model.setter
-  def model(self, value):
-    """
-    Set model (name, indicated in capacity)
-    :param value: str
-    """
-    if self._model is None:
-      self._model = value
-
-  @property
-  def cooling_capacity(self) -> List[float]:
-    """
-    Get cooling capacity in kW
-    :return: [[float]]
-    """
-    return self._cooling_capacity
-
-  @cooling_capacity.setter
-  def cooling_capacity(self, value):
-    """
-    Set cooling capacity in kW
-    :param value: [[float]]
-    """
-    if self._cooling_capacity is None:
-      self._cooling_capacity = value
-
-  @property
-  def cooling_comp_power(self) -> List[float]:
-    """
-    Get cooling compressor power input in kW
-    :return: [[float]]
-    """
-    return self._cooling_comp_power
-
-  @cooling_comp_power.setter
-  def cooling_comp_power(self, value):
-    """
-    Set the cooling compressor in kW
-    :param value: [[float]]
-    :return:
-    """
-    if self._cooling_comp_power is None:
-      self._cooling_comp_power = value
-
-  @property
-  def cooling_capacity_coff(self) -> List[float]:
-    """
-    Get cooling capacity coefficients
-    :return: [float]
-    """
-    return self._cooling_capacity_coff
-
-  @cooling_capacity_coff.setter
-  def cooling_capacity_coff(self, value):
-    """
-    Set the value for cooling capacity coefficients
-    :param value: [float]
-    :return:
-    """
-    if self._cooling_capacity_coff is None:
-      self._cooling_capacity_coff = value
-
-  @property
-  def cooling_comp_power_coff(self) -> List[float]:
-    """
-    Get cooling compressor power coefficients
-    :return: [float]
-    """
-    return self._cooling_comp_power_coff
-
-  @cooling_comp_power_coff.setter
-  def cooling_comp_power_coff(self, value):
-    """
-    Set the value for cooling compressor power coefficients
-    :param value: [float]
-    :return:
-    """
-    if self._cooling_comp_power_coff is None:
-      self._cooling_comp_power_coff = value
-
-
-
-  @property
-  def heating_capacity(self) -> List[float]:
-    """
-    Get heating capacity kW
-    :return: [[float]]
-    """
-    return self._heating_capacity
-
-  @heating_capacity.setter
-  def heating_capacity(self, value):
-    """
-    Set the heating capacity in kW
-    :param value: [[float]]
-    :return:
-    """
-    if self._heating_capacity is None:
-      self._heating_capacity = value
-
-  @property
-  def heating_comp_power(self) -> List[float]:
-    """
-    Get heating compressor power kW
-    :return: [[float]]
-    """
-    return self._heating_comp_power
-
-  @heating_comp_power.setter
-  def heating_comp_power(self, value):
-    """
-    Set the heating compressor power in kW
-    :param value: [[float]]
-    :return:
-    """
-    if self._heating_comp_power is None:
-      self._heating_comp_power = value
-
-  @property
-  def heating_comp_power_coff(self) -> List[float]:
-    """
-    Get heating compressor power coefficients
-    :return: [float]
-    """
-    return self._heating_comp_power_coff
-
-  @heating_comp_power_coff.setter
-  def heating_comp_power_coff(self, value):
-    """
-    Set the value for heating compressor power coefficients
-    :param value: [float]
-    :return:
-    """
-    if self._heating_comp_power_coff is None:
-      self._heating_comp_power_coff = value
-
-  @property
-  def heating_capacity_coff(self) -> List[float]:
-    """
-    Get heating capacity coefficients
-    :return: [float]
-    """
-    return self._heating_capacity_coff
-
-  @heating_capacity_coff.setter
-  def heating_capacity_coff(self, value):
-    """
-    Set the value for heating capacity coefficients
-    :param value: [float]
-    :return:
-    """
-    if self._heating_capacity_coff is None:
-      self._heating_capacity_coff = value
-
-
diff --git a/city_model_structure/energy_systems/water_to_water_hp.py b/city_model_structure/energy_systems/water_to_water_hp.py
new file mode 100644
index 00000000..e69de29b
diff --git a/data/energy_systems/heat_pumps/Air Source.xlsx b/data/energy_systems/heat_pumps/Air Source.xlsx
deleted file mode 100644
index c0ea122f..00000000
Binary files a/data/energy_systems/heat_pumps/Air Source.xlsx and /dev/null differ
diff --git a/imports/energy_systems/xlsx_heat_pump_parameters.py b/imports/energy_systems/air_source_hp_parameters.py
similarity index 89%
rename from imports/energy_systems/xlsx_heat_pump_parameters.py
rename to imports/energy_systems/air_source_hp_parameters.py
index b1b96e70..7e62f1af 100644
--- a/imports/energy_systems/xlsx_heat_pump_parameters.py
+++ b/imports/energy_systems/air_source_hp_parameters.py
@@ -1,13 +1,12 @@
 """
-XlsxHeatPumpParameters import the heat pump information
+AirSourceHeatPumpParameters import the heat pump information
 SPDX - License - Identifier: LGPL - 3.0 - or -later
-Copyright © 2020 Project Author Peter Yefi peteryefi@gmail.com
-Contributor Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
+Copyright © 2021 Project Author Peter Yefi peteryefi@gmail.com
 """
 
 import pandas as pd
 from typing import Dict
-from city_model_structure.energy_systems.heat_pump import HeatPump
+from city_model_structure.energy_systems.air_source_hp import AirSourceHP
 from city_model_structure.energy_system import EnergySystem
 from scipy.optimize import curve_fit
 import numpy as np
@@ -15,14 +14,14 @@ from typing import List
 import itertools
 
 
-class XlsxHeatPumpParameters:
+class AirSourceHeatPumpParameters:
   """
-  XlsxHeatPumpParameters class
+  AirSourceHeatPumpParameters class
   """
 
   def __init__(self, city, base_path):
     self._city = city
-    self._base_path = (base_path / 'heat_pumps/Air source.xlsx')
+    self._base_path = (base_path / 'heat_pumps/air_source.xlsx')
 
   def _read_file(self) -> Dict:
     """
@@ -31,6 +30,7 @@ class XlsxHeatPumpParameters:
     :return : Dict
     """
     xl_file = pd.ExcelFile(self._base_path)
+
     heat_pump_dfs = {sheet_name: xl_file.parse(sheet_name)
                      for sheet_name in xl_file.sheet_names}
 
@@ -38,8 +38,10 @@ class XlsxHeatPumpParameters:
     heating_data = {}
 
     for sheet, dataframe in heat_pump_dfs.items():
-      if sheet == "Summary":
-        continue
+
+      if 'Summary' in sheet:
+       continue
+
       # Remove nan rows and columns and extract cooling and heating data
       # for each sheet
       df = heat_pump_dfs[sheet].dropna(axis=1, how='all')
@@ -65,10 +67,10 @@ class XlsxHeatPumpParameters:
     """
     Enriches the city with information from file
     """
-    heap_pump_data = self._read_file()
+    heat_pump_data = self._read_file()
     for (k_cool, v_cool), (k_heat, v_heat) in \
-        zip(heap_pump_data["cooling"].items(), heap_pump_data["heating"].items()):
-      heat_pump = HeatPump()
+        zip(heat_pump_data["cooling"].items(), heat_pump_data["heating"].items()):
+      heat_pump = AirSourceHP()
       heat_pump.model = k_cool
       h_data = self._extract_heat_pump_data(v_heat)
       c_data = self._extract_heat_pump_data(v_cool)
@@ -82,7 +84,7 @@ class XlsxHeatPumpParameters:
       heat_pump.heating_comp_power_coff = self._compute_coefficients(h_data[1])
 
       energy_system = EnergySystem('{} capacity heat pump'.format(heat_pump.model), 0, [], None)
-      energy_system.heat_pump = heat_pump
+      energy_system.air_source_hp = heat_pump
       self._city.add_city_object(energy_system)
     return self._city
 
diff --git a/imports/energy_systems/water_to_water_hp_parameters.py b/imports/energy_systems/water_to_water_hp_parameters.py
new file mode 100644
index 00000000..e69de29b
diff --git a/unittests/test_energy_systems_factory.py b/unittests/test_energy_systems_air_source_hp.py
similarity index 78%
rename from unittests/test_energy_systems_factory.py
rename to unittests/test_energy_systems_air_source_hp.py
index eb8bb7dd..ecdfdd5a 100644
--- a/unittests/test_energy_systems_factory.py
+++ b/unittests/test_energy_systems_air_source_hp.py
@@ -7,7 +7,7 @@ import pandas as pd
 from unittest import TestCase
 from imports.geometry_factory import GeometryFactory
 from imports.energy_systems_factory import EnergySystemsFactory
-from city_model_structure.energy_systems.heat_pump import HeatPump
+from city_model_structure.energy_systems.air_source_hp import AirSourceHP
 from exports.energy_systems_factory import EnergySystemsExportFactory
 import os
 
@@ -25,15 +25,15 @@ class TestEnergySystemsFactory(TestCase):
     city_file = "../unittests/tests_data/C40_Final.gml"
     self._output_path = "../unittests/tests_data/user_output.csv"
     self._city = GeometryFactory('citygml', city_file).city
-    EnergySystemsFactory('xlsx heat pump', self._city).enrich()
+    EnergySystemsFactory('air source hp', self._city).enrich()
 
-  def test_heat_pump_import(self):
+  def test_air_source_heat_pump_import(self):
     self.assertIsNotNone(self._city.energy_systems, 'City has energy systems')
-    self.assertIsInstance(self._city.energy_systems[0].heat_pump, HeatPump)
-    self.assertEqual(self._city.energy_systems[0].heat_pump.model, '012')
-    self.assertEqual(self._city.energy_systems[len(self._city.energy_systems) - 1].heat_pump.model, '140')
+    self.assertIsInstance(self._city.energy_systems[0].air_source_hp, AirSourceHP)
+    self.assertEqual(self._city.energy_systems[0].air_source_hp.model, '012')
+    self.assertEqual(self._city.energy_systems[len(self._city.energy_systems) - 1].air_source_hp.model, '140')
 
-  def test_heat_pump_export(self):
+  def test_air_source_heat_pump_export(self):
     # User defined paramenters
     user_input = {
       'StartYear': 2020,
diff --git a/unittests/test_energy_systems_water_to_water_hp.py b/unittests/test_energy_systems_water_to_water_hp.py
new file mode 100644
index 00000000..e69de29b