diff --git a/nifty/spaces/gl_space/gl_space.py b/nifty/spaces/gl_space.py
similarity index 99%
rename from nifty/spaces/gl_space/gl_space.py
rename to nifty/spaces/gl_space.py
index 619764e8ec98f3bdb4e1b5e71c4d996982067ab3..a40354506f9e2050df7158319714acc8f1abef5c 100644
--- a/nifty/spaces/gl_space/gl_space.py
+++ b/nifty/spaces/gl_space.py
@@ -18,7 +18,7 @@
 
 from __future__ import division
 import numpy as np
-from ..space import Space
+from .space import Space
 
 
 class GLSpace(Space):
diff --git a/nifty/spaces/gl_space/__init__.py b/nifty/spaces/gl_space/__init__.py
deleted file mode 100644
index da4756ccc56229189e0550f70a99d21f779e7a7a..0000000000000000000000000000000000000000
--- a/nifty/spaces/gl_space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .gl_space import GLSpace
diff --git a/nifty/spaces/hp_space/hp_space.py b/nifty/spaces/hp_space.py
similarity index 99%
rename from nifty/spaces/hp_space/hp_space.py
rename to nifty/spaces/hp_space.py
index 261c1ad1c9f28d9aa61cf3e6014cf715b0ef4b0e..528207e60648c86859a1320ad1ded890281563d7 100644
--- a/nifty/spaces/hp_space/hp_space.py
+++ b/nifty/spaces/hp_space.py
@@ -18,8 +18,7 @@
 
 from __future__ import division
 import numpy as np
-
-from ..space import Space
+from .space import Space
 
 
 class HPSpace(Space):
diff --git a/nifty/spaces/hp_space/__init__.py b/nifty/spaces/hp_space/__init__.py
deleted file mode 100644
index 6854432141e63d4d3b4e80c009358a5d8c758d17..0000000000000000000000000000000000000000
--- a/nifty/spaces/hp_space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .hp_space import HPSpace
diff --git a/nifty/spaces/lm_space/lm_space.py b/nifty/spaces/lm_space.py
similarity index 99%
rename from nifty/spaces/lm_space/lm_space.py
rename to nifty/spaces/lm_space.py
index b04ecb04e80aa49bb5c8331ad1459f4ca5155792..c38e67a68f445478acaa246a13e4207efcb6eea3 100644
--- a/nifty/spaces/lm_space/lm_space.py
+++ b/nifty/spaces/lm_space.py
@@ -17,10 +17,8 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
-
 import numpy as np
-
-from ..space import Space
+from .space import Space
 
 
 class LMSpace(Space):
diff --git a/nifty/spaces/lm_space/__init__.py b/nifty/spaces/lm_space/__init__.py
deleted file mode 100644
index 2c663e5b93143114df194efed410bd1d023d1b70..0000000000000000000000000000000000000000
--- a/nifty/spaces/lm_space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .lm_space import LMSpace
diff --git a/nifty/spaces/power_space/power_space.py b/nifty/spaces/power_space.py
similarity index 94%
rename from nifty/spaces/power_space/power_space.py
rename to nifty/spaces/power_space.py
index e5eb327032600df27b16a36d60a8a4a80a9af744..4698027d601a9bb22d31e94e82a92c0914380891 100644
--- a/nifty/spaces/power_space/power_space.py
+++ b/nifty/spaces/power_space.py
@@ -17,10 +17,9 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import numpy as np
-
-from ...spaces.space import Space
+from .space import Space
 from functools import reduce
-from ... import dobj
+from .. import dobj
 
 
 class PowerSpace(Space):
@@ -51,9 +50,6 @@ class PowerSpace(Space):
         mapped to which power bin
     k_lengths : numpy.ndarray
         Sorted array of all k-modes.
-    rho : numpy.ndarray
-        The amount of k-modes that get mapped to one power bin is given by
-        rho.
     dim : np.int
         Total number of dimensionality, i.e. the number of pixels.
     harmonic : bool
@@ -148,7 +144,11 @@ class PowerSpace(Space):
         if not (isinstance(harmonic_partner, Space) and
                 harmonic_partner.harmonic):
             raise ValueError("harmonic_partner must be a harmonic space.")
+        if harmonic_partner.scalar_dvol() is None:
+            raise ValueError("harmonic partner must have "
+                             "scalar volume factors")
         self._harmonic_partner = harmonic_partner
+        pdvol = harmonic_partner.scalar_dvol()
 
         if binbounds is not None:
             binbounds = tuple(binbounds)
@@ -165,12 +165,13 @@ class PowerSpace(Space):
             temp_k_lengths = np.bincount(temp_pindex.ravel(),
                                       weights=k_length_array.ravel()) \
                 / temp_rho
+            temp_dvol = temp_rho*pdvol
             self._powerIndexCache[key] = (binbounds,
                                           temp_pindex,
                                           temp_k_lengths,
-                                          temp_rho)
+                                          temp_dvol)
 
-        (self._binbounds, self._pindex, self._k_lengths, self._rho) = \
+        (self._binbounds, self._pindex, self._k_lengths, self._dvol) = \
             self._powerIndexCache[key]
 
     @staticmethod
@@ -199,7 +200,10 @@ class PowerSpace(Space):
         return self.shape[0]
 
     def scalar_dvol(self):
-        return 1.
+        return None
+
+    def dvol(self):
+        return self._dvol
 
     def get_k_length_array(self):
         return self.k_lengths.copy()
@@ -232,9 +236,3 @@ class PowerSpace(Space):
         """ Sorted array of all k-modes.
         """
         return self._k_lengths
-
-    @property
-    def rho(self):
-        """Degeneracy factor of the individual k-vectors.
-        """
-        return self._rho
diff --git a/nifty/spaces/power_space/__init__.py b/nifty/spaces/power_space/__init__.py
deleted file mode 100644
index 36c265fcfa9ad642f552148a589e7eb5bd440568..0000000000000000000000000000000000000000
--- a/nifty/spaces/power_space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .power_space import PowerSpace
diff --git a/nifty/spaces/rg_space/rg_space.py b/nifty/spaces/rg_space.py
similarity index 99%
rename from nifty/spaces/rg_space/rg_space.py
rename to nifty/spaces/rg_space.py
index 39463fcd6a810097915d85b6ecfc9da657d15c65..8b921bcead9942c3b38a4ce09efe9ea1979efa99 100644
--- a/nifty/spaces/rg_space/rg_space.py
+++ b/nifty/spaces/rg_space.py
@@ -32,7 +32,7 @@ from __future__ import division
 from builtins import range
 from functools import reduce
 import numpy as np
-from ..space import Space
+from .space import Space
 
 
 class RGSpace(Space):
diff --git a/nifty/spaces/rg_space/__init__.py b/nifty/spaces/rg_space/__init__.py
deleted file mode 100644
index 3a82b483002ccad6b1c68646ff3933911c4774b7..0000000000000000000000000000000000000000
--- a/nifty/spaces/rg_space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .rg_space import RGSpace
diff --git a/nifty/spaces/space/space.py b/nifty/spaces/space.py
similarity index 98%
rename from nifty/spaces/space/space.py
rename to nifty/spaces/space.py
index b37127af2bc6bc2c8c8d84b9c974e657cd7f67c8..025ebc326a90a91b74ff2ab6f273e9749d3982b5 100644
--- a/nifty/spaces/space/space.py
+++ b/nifty/spaces/space.py
@@ -18,7 +18,7 @@
 
 import abc
 
-from ...domain_object import DomainObject
+from ..domain_object import DomainObject
 
 
 class Space(DomainObject):
diff --git a/nifty/spaces/space/__init__.py b/nifty/spaces/space/__init__.py
deleted file mode 100644
index 6ce7924251cfadfc1414004dfdbd77108a06036b..0000000000000000000000000000000000000000
--- a/nifty/spaces/space/__init__.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-# Copyright(C) 2013-2017 Max-Planck-Society
-#
-# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
-# and financially supported by the Studienstiftung des deutschen Volkes.
-
-from .space import Space