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The Velux Building
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
More
information...
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building”
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Project presentation (1...)
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring

The Velux building is situated in central Switzerland in the tableland.

This area is characterised by a moderate and sometimes windy climate.

The building was renovated in 1992: the former flat roof was topped by two
additional floors with tilted outside walls resulting in the new roof.

The building is used as an administration building of a factory for window
fittings.

The building has many cellular offices, an open plan office and a big
show room. The rooms have a lot of internal mass: exposed ceilings and
tiled floors (the internal walls and external walls are light-weight
constructions).
The summer
monitoring
Major
findings
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information...
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Project presentation (2...)
The VELUX
building
Presentation
of the building
The design
issue

A production facilities for
windows fittings is attached
to the back of the building.

The building is located in a
quiet industrial zone next
to a low frequented road at
the edge of a river. Noise
and pollution are not a
problem.
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
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information...
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Part under investigation
Project presentation (3...)
The VELUX
building
Presentation
of the building
Open plan
office
The design
issue
The building
concept
The winter
monitoring
Cellular
offices
The summer
monitoring
Major
findings
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information...
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Factory
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Part under investigation
Project presentation (4...)
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The basement and the
two lower floors consist of
cellular offices.
The winter
monitoring
The summer
monitoring
Major
findings
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1st floor
Project presentation (5|)
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The two top floors are
designed as an open
plan office (2dn floor)
and a show room (3rd
floor).
The winter
monitoring
The summer
monitoring
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findings
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3rd floor
The design issue (1...)
The VELUX
building
Presentation
of the building

As the building is used for
the administration of a
window fitting factory,
window fixtures and fittings
are seen as very important
features by the occupants.

Windows furnished with
electronic actuators
represent one of the new
products of the company.

The windows are
automatically controlled with
a manual override . This
improves the useracceptance.
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
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information...
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Windows furnished
with electronic actuators
The design issue (2|)
The VELUX
building
Presentation
of the building
The design
issue


The building
concept
The aim is for the occupants to get natural
ventilation via the windows with electronic
actuators.
Thanks to the open architecture of the staircase
of the building the stack effect is considered
to provide a sufficiently strong force for
ventilation.
The winter
monitoring
The summer
monitoring

Major
findings
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information...
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To achieve the goals three control strategies were used:
 Automatically timer controlled system (e.g. for night ventilation and
cross ventilation during the work breaks),
 Automatically opened windows depending on weather conditions
(e.g. wind velocity, rain).
 Manual operated system (The windows can also be manually
controlled during working hours),
The building concept (1...)
Indoor Air Quality during office hours
The VELUX
building
Presentation
of the building
Strategy for IAQ:

During breaks (early in the
morning and at noon) the
windows are automatically
(time controller) opened for 5
minutes to ventilate the
building.

During the heating season, the
building is only ventilated
during some periods to avoid
too high ventilation losses
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
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information...
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building”
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The building concept (2...)
global strategy for summer comfort
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The risk of overheating is reduced by:

Shading devices: external screens are installed on the all façades. The
screens are controlled manually.

The winter
monitoring
The summer
monitoring
Major
findings
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information...
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The building and the thermal mass (exposed ceilings) of the building is
cooled down by intensive ventilation based on the stack effect. The
windows are automatically opened:
 during working hours in the afternoon if the outside temperature is
higher than the inside temperature

at night (time control)

Moreover, the automatic control of the windows take weather
conditions into account (see next slide...  ).
The building concept (3...)
automatic control & outside conditions
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
nice weather
nice weather and wind
3rd floor
Ventilation control is a
function of external
conditions (see
schematic).
2nd floor
1st floor
Ground floor
Basement
rain
rain and wind
The outside conditions
are measured by rain
and wind sensors.
3rd floor
2nd floor
1st floor
Ground floor
Basement
Major
findings
More
information...
south-west
south-east
north-east
south-west
south-east
closed
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always closed (security)
open
north-east
The building concept (4...)
overview
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
More
information...
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building”
Summertime
during office
hours
outside
office hours
Wintertime
during office
hours
 timecontrolled short
time ventilation
during breaks -
intensive
ventilation
(weather
controlled) - to
 timecontrolled short
time ventilation
during breaks -
to improve IAQ
improve summer
comfort
to improve IAQ
 if Text< Tint:
intensive
ventilation
(weather
controlled) - to
improve summer
comfort
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outside
office hours
no ventilation
The building concept (5|)
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
More
information...
user acceptance through independence
during working hours
All the automatically controlled
windows can also be
controlled manually (see
control device). This permits
the building users to operate
the desired windows during
the working hours in
accordance with their required
comfort.
This increases the user
acceptance of the system.
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Slide with monitoring set-up
The VELUX
building
Presentation
of the building




The design
issue


The building
concept
Carbon Dioxide (CO2 ),
Ventilation Rate,
Temperature
Humidity,
Indoor air velocity
were made over one week periods during

The winter
monitoring

February 1997,
August 1997,
in
The summer
monitoring
Major
findings
More
information...
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Continuous measurements of

the meeting room in the basement

one cellular office on the ground floor

two cellular offices on the first floor (south-west and north-east façade)

one open plan on the second floor

the show room on the third floor
The cellular office on the first floor on the south-west building side was selected as being
representative. The monitoring results of this office is shown in the following chart.
NatVent
Winter monitoring (1...)
typical winter day - monitoring results
20
15
Occupants open the windows because of
too high temperatures  relatively high
ventilation losses
10
5
-5
No ventilation at night = No ventilation losses
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-10
26-28.02.1997
Indoor Temperature [°C]
Air Change [1/h]
Outside Temperature [°C]
00
21
18
15
12
09
06
03
00
21
18
15
12
09
06
03
0
00
Major
findings
More
information...
25
21
The summer
monitoring
30
18
The winter
monitoring
35
15
The building
concept
Indoor temperature sometimes too
high due to problem with control of
heating system
12
The design
issue
40
Indoor and outside temp. - air change rate
The VELUX
building
Presentation
of the building
Winter monitoring (2...)
typical winter day - monitoring results
40
The design
issue
30
Major
findings
More
information...
25
20
15
600
10
400
5
00
21
18
15
12
09
06
03
00
21
18
15
12
09
06
03
00
21
12
0
200
-5
-10
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800
18
The summer
monitoring
1000
Good Indoor Air Quality
15
The winter
monitoring
CO2 rises during the office hours never
above 1200 ppm (max. conc. :guideline)
35
Indoor and outside temp.
air change rate,
The building
concept
1200
CO2 concentr.
The VELUX
building
Presentation
of the building
Windows are during some minutes autom. opened in the morning
0
26-28.02.1997
Indoor Temperature [°C]
NatVent
Air Change [1/h]
Outside Temperature [°C]
Carbon Dioxide [ppm]
Winter monitoring (3|)
typical winter day - monitoring results
The VELUX
building
Presentation
of the building

Due to a problem with the control of the heating system, indoor
temperatures were too high. For this reason windows were manually
opened to cool the building. This leads to high ventilation losses. It is clear
that a better heating control will result in a considerable reduction of the
heating consumption in wintertime.

At night all windows are well closed to avoid ventilation losses.

The IAQ in the offices is always acceptable (<1200ppm).
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Major
findings
More
information...
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building”
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Summer monitoring (1...)
typical summer day - monitoring results
The VELUX
building
Presentation
of the building
The building
concept
The winter
monitoring
The summer
monitoring
Very warm day (34°C)
35
Indoor and outside temp.
air change rate,
The design
issue
40
Major
findings
More
information...
Acceptable peak indoor temperature (28°C)
30
25
20
Intensive
night
ventilation
( >10 ACH )
15
10
Indoor
temperature
drops due to
night ventilation
5
0
12
15
18
21
00
03
06
09
12
15
18
21
00
03
06
09
12
15
18
21
00
25-27.08.1997
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IndoorTemperature [°C]
Air Change [1/h]
Outside temperature [°C]
Summer monitoring (2...)
typical summer day - monitoring results
The VELUX
building
Presentation
of the building
40
35
The design
issue
The winter
monitoring
The summer
monitoring
Major
findings
More
information...
The influence on the IAQ is given on next slide...
Indoor and outside temp.
air change rate,
The building
concept
= Windows are automatically opened at 8,13 and 18h
to improve the IAQ. The other ventilation peaks are due
to manually opened windows.
30
25
20
Intensive
night
ventilation
(>10 ACH)
15
10
5
0
12
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15
18
21
00
03
06
09
12
15
18
21
00
03
06
09
12
15
18
21
00
25-27.08.1997
IndoorTemperature [°C]
Air Change [1/h]
Outside temperature [°C]
Summer monitoring (3|)
typical summer day - monitoring results
The building
concept
The winter
monitoring
The summer
monitoring
35
Indoor and outside temp.
air change rate,
The design
issue
40
Major
findings
More
information...
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1200
The IAQ is always below the limit of 1200 ppm
1000
30
800
25
20
600
15
400
10
200
5
0
0
12
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There is a clear relation between IAQ during the office
hours and the air change rate: High ventilation rate 
low CO2 concentration
15
18
21
00
03
06
09
12
IndoorTemperature [°C]
Outside temperature [°C]
15
18
21
25-27.08.1997
00
03
06
09
12
15
18
21
Air Change [1/h]
Carbon dioxide [ppm]
00
Carbon dioxide
The VELUX
building
Presentation
of the building
Major findings (1...)
summer comfort
The VELUX
building
Presentation
of the building

The design
issue



The summer
monitoring
Major
findings
More
information...
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building”
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Thanks to the night ventilation and the shading devices, big overheating
problems were avoided.
Shading devices:

The building
concept
The winter
monitoring
Summer comfort:
The efficacy of the external screens could be increased by an automatic
control instead of manual control.
Night Cooling:

For security reasons, windows on the ground floor are not opened at
night  no night cooling. Therefore the offices on the ground floor have
an appreciable overheating problem in summer.

User behaviour: Closed doors during the night obstruct often the night
cooling in summertime. Clear user instructions could help.

A comparison of inside and outside temperature suggest that the night
cooling effect could be used even more intensively by opening the
windows at least 3 hours earlier.
Major findings (2...)
summer comfort
The VELUX
building
Presentation
of the building

The design
issue
The building
concept
The winter
monitoring
Night Cooling (optimisation of ventilation & stack effect):

The openable area on each floor produced an unequal air change rate
which resulted in a reduced night cooling effect and an increased risk
on overheating for the upper floors.

A better analysis of the relation between the opening surfaces and
their height above the ground (analysis of the neutral level pressure)
can increase the night cooling efficiency.
The summer
monitoring
BETTER...
Major
findings
More
information...
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Pressure diff. line
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Pressure diff. line
Major findings (3|)
indoor air quality
The VELUX
building
Presentation
of the building


Due to problems with the controls for the heating system
indoor temperatures were too high. Windows are opened to cool
the building. This lead to unnecessary ventilation losses. In order
to avoid ventilation due to overheating in winter, the heating
supplied to the offices on the south-west building side should be
reduced significantly especially in the sunny winter afternoons.
 The IAQ is acceptable
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
In Winter:

Major
findings
More
information...
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In Summer:

The IAQ is acceptable
More information...
The VELUX
building
Presentation
of the building
The design
issue
The building
concept
The winter
monitoring
The summer
monitoring
Find more information on the PROBE building in the following documents:
\Reports \Monitoring Reports \Summary Reports\ch1summ.pdf
 global presentation of the buildings (4p./building)
 contents: building description - ventilation strategy and technology winter and summer monitoring results - conclusions
\Reports \Monitoring Reports \Detailed Reports\ch1det.pdf
 detailed reports of all 19 monitoring campaigns (20p./campaign)
 contents: monitoring set up - analysis of results - conclusions
Major
findings
More
information...
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run the installation file ar32e301(1).exe in the directory
\Installation