153 ResidencesA combined residence/office building was
built in 1992 within a residential suburb
of Kassel, Germany, that built according to
ecological standards. All main rooms as well
as a bathroom and the winter garden are
covered with earthen domes. The entrance
is covered by three jack vaults built of green
bricks, as explained in chapter 14. The cen-
tral lobby is covered by a dome with a clear
span of 5.2 m and a clear height of 4.6 m,
which is provided with a skylight consisting
of a double-layered acrylic glass dome.
Leading off from this lobby are four addi-
tional domed rooms. Each room has the
same span, with a clear height of 4 m, and
each is provided with a central skylight and
one window at normal height. The con-
struction of these five domes was carried
out using the rotational guide described
in chapter 14. Though the central dome
springs from a height of 1.75 m, and the
domes of the four other rooms at heights
of 0.75 m, no ring beam is necessary, the
structure being designed so that all resultant
forces fall within the middle third of the
foundations. The domes in the bathroom
and winter garden are formed over an
irregular hexagon, and were built using a
technique derived from the Afghan dome
technique (see chapter 14) using arches
inclined at angles of 40-60° from the hori-
zontal.
The eye-shaped opening remaining once
the two sets of arches reach the point at
which they converge is covered by changing
the pattern of arches by 90°. All domes are
covered with an additional layer of 20 cm
rock wool for thermal insulation and sealed
with a 2-mm-thick, hot-air welded rein-
forced plastic membrane, which is water-
proof and ‘root-proof’. This is covered with
15 cm of earth, which acts as substrate for
the frost-resistant and drought-resistant wild
grasses.
The single-storeyed house has a floor area
of 216 m^2 , including the winter garden.
Walls, shelves and sanitary objects are cov-