General information
The project consists of a residential multi family house to be built on Sickla Udde in
Hammarby Sjöstad, a new residential area, south of the city center of Stockholm. The PV
building is a house with high demands on the environmental standard. A neighbor house with
a similar architectural exterior will be built as a reference with normal environmental
standard.
Site information
Hammarby Sjöstad, along with Södra Länken, is Stockholm’s on-going urban development
project. An old dockland and industrial area is being transformed into a modern city area that
will form a logical extension of Södermalm, with 8, 000 apartments housing a population of
20,000. After completion of all parts of the project in 2010 there will be 30,000 people living
and working in the area.
Environmentally Hammarby Sjöstad will be a well-planned area with its own recycling model
and its own local sewage treatment plant. Hammarby Sjöstad will have an inner-city character
with new, exciting architecture. Unique qualities and opportunities flow from the waterside
location and the proximity of both the inner city and the Nacka Nature Reserve.
In a further response to environmental concerns, Hammarby Sjöstad will be well provided
with transportation options including the Tvärbanan tramline, ferries across the Hammarby
Canal, and car pooling arrangements. Plans also include a highly developed network of
pedestrian and cycling paths.
The area will have a strong environmental profile and large efforts have been put into the
project to make it the spearhead for the future building projects in Sweden. The use of PV is
an important part in this context.
 1. Aerial photograph of Södermalm and Hammarby Sjöstad.
2. General plan of Hammarby Sjöstad.
The object
The Familjebostäder project consists of a multi-family building block where the PV will be
installed partly on the façade and partly on the roof. The façade part of the PV installation is
designed as a lamella structure that will be mounted outside the building as an independent
element. This house is designed to be an experimental building with high demands on the
environmental standard. A neighbor house with a similar architectural exterior will be built as
a reference with normal environmental standard. They will be located on Sickla Udde on the
south side of the lake, Hammarby Sjö.
 1. The neighborhood at Sickla Kaj.
2. The Familjebostäder building – PV-building to the right and reference building to the left.
The southwest facing façade will be provided with 113 m 2 of semitransparent PV modules
that will be integrated in a lamella structure. 122 m 2 of conventional PV-modules will cover
almost all area of the west, south and east facing parts of the roof. The façade construction can
be easily dismantled in case of repair or maintenance and then be erected again without risk of
destroying exterior parts of the building. The density and angle of the modules in the façade
has been carefully optimized with respect to energy output and esthetical appearance.
The calculated energy production from the building is 17 MWhAC/year including losses when
dc-energy is converted to alternating current in a string inverter. A minor hill, covered with
old oaks, is located right in front of the building. The hill will partly shadow the façade during
hours with low solar angles. It has been estimated that the annual energy production is
decreased by less than 10 % due to this shadowing.
The produced energy will provide the necessary demand of household electricity and common
needs such as lighting in the staircase, elevators, fans etc. But it will not cover the electrical
energy required by the heat pump. All calculations assumes that energy can be exported at
summertime and imported in wintertime.
Details of the façade part of the PV installation
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The orientation of the building is 22° towards west relative to the south axis. The oakhill is indicated. Highest part of the hill in darker color.
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The principle of a lamella structured façade, with a tilt of 45° of the modules.
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The PV installation on the façade is designed as a lamella structure, freestanding, half a
meter outside the building. There are 10 rows of module per story (2,9 meters) and four
stores on the building. The first story is free from modules in order to prevent children
to climb on or touch the modules and to decrease problems related to shadowing. In
front of a window every second row of modules is removed in order allow more light in
to the rooms. White Arkitekter develops the lamella construction in this project.
”Custom designed semitransparent module” The module that will be used in the
lamella structure is made with 22 cells, each with a size of 100 x 100 mm2 . The cells are
connected in 2 parallel strings with 11 series connected cells in each. The spacing
between cells and from cells to the long edges of the module is 20 mm. The outer size of
the module is 1380 x 260 mm2 , and the peak power is 30,8 watt, assuming that cells
with an encapsulated efficiency of 14% are available. The thickness of the module is 8
mm due to the encapsulation of cells between two 4 mm tempered glass sheets.
The modules in the lamella structure are tilted 45%. In front of the windows every second
row of module are removed in order to allow more light in to the rooms. The above figure
shows the principle of the structure. In the actual design the density of the lamellas is
somewhat higher, 10 modules per story which equals one module/0,29 meters. (A
module is 0,26 m wide)
Detail of construction, showing a top view of the outer wall of the facade (right part of
the drawing) and the lamella arranged PV-modules (left part of the drawing)
Monthly variation of the solar irradiation on the lamella surface on the upper part of the
façade. Meteorological data for Stockholm 1991 are used in the calculations.
Modules of a conventional type are mounted on the three parts of the roof that are facing
west, south and east. Each module has a nominal size of 1200 x 600 mm2 and with a
nominal output of 94 watts. The tilt of the roof is only 16%, which means that the energy
production is less sensitive to the fact that two parts of the roof are not facing south.
A total number of 169 modules will be mounted on the roof. 52 modules on the south, 59
on the west and 58 on the east part of the roof. Module installation will take place on top
of the tin roof that is planned to cover the building. The 122 m2 of PV-modules on the
roof has a peak power of 15,8 kW and the calculated energy production is 11,6 MWhAC
per year. The arrow points at the lamella structure viewed from above.
Monitoring of PV production and energy consumption
The project has identified the importance of making the tenants involved in the operation of
the PV project. The energy consumption in the building and the production from the PV
installation will be monitored and data will be presented on a display, located in the staircase
where it also will be possible to compare the energy consumption with the neighboring
reference house.
Additional information on environmental and energy related issues
A detailed environmental profile has been produced for the project which include all steps
from planning, building adaptation to the terrain, local climate noise, air quality, magnetic
fields, air temperature - considering vegetation, solar radiation and wind effects, water and
waste treatment, recycling, composting etc. As for energy usage this means 37 kWh per m 2
and year of bought energy. The area used in calculations is the sum of all residential and non-residential
areas (898 m2 ). This has been achieved through the design of an extremely energy
efficient building with thick insulation; best window technology available on the market (U-value
of 1,0 W/m2 K) controlled ventilation and the selection of energy efficient appliances.
The use of PV is also a means of reaching the goal as only bought energy is calculated. Other
means of energy supply are:
- All cooking is made on stoves, fueled from biogas that is locally produced from collected
waste in the area of “Hammarby Sjöstad”.
- Heat is extracted from the surrounding ground by a heat pump with a heat factor of 3,1.
- The energy in used air is recycled.
The bought energy can be divided in two mayor parts. 26 kWh/m2 (electricity) which is
required by the heat pump and recycling of used air. 9 kWh/m2 (biogas) used by the stoves
and peak heating in wintertime. The reference house is calculated to consume 125 kWh/m2.
Timetable
The construction of the building will start in September 2001 with the PV installation starting
in April 2002. The building is completed in fall 2002.
Budget and financing
The total budget for the building is estimated to 1,74 MEuro. Of this is 0,39 MEuro related to
the extra costs caused by the innovative energy and environmental components compared to
standard products. The PV plant on the building will cost approximately 0,178 MEuro. (7
Euro/kWp). Familjebostäder finances the project with a 30% subsidy for the innovative parts
related to the environmental efforts. This subsidy comes from the local investment program
(LIP), a governmental financed program for supporting national initiatives for the creation of
a sustainable society. Familjebostäder gained the third prize in a competition, "Best building
in Hammarby Sjöstad", which has given an extra financial contribution to the project.
Partners
Familjebostäder carries out the project and the architect is White Architects. Other mayor
consultants are Tyréns Byggkonsult (reference house), K-Konsult (Electrical installations,
including the PV), ÅF-VVS Projekt (Heating) and Energibanken (PV). The PV supplier has
not yet been selected, as this will be subject of an open tender.
Contribution to the PV-NORD project
The project will demonstrate how PV can be integrated in a lamella structure in front of a
façade of an architecturally conventional building in Stockholm, Sweden. From the very
beginning the architecturally constraints have been to find an application where the PV
modules will be heavily exposed in order to catch peoples attention as much as possible, and
hereby increasing the awareness of photovoltaics as an emerging new and sustainable energy
source.
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