Download Tax Office of Enschede

Tax Office of Enschede
Tax Office of
Enschede
S.H. Liem, A.H.C. van Paassen
Delft, April 1998
Presentation
of the building
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Winter
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Building presentation
background information

The Tax Office of Enschede was completed in 1996. It is located near the
central railway station. It has offices on 5 floors and a total floor area of
4300 m2. The building is wedge shaped (see ground plan on next slide
...).
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
It is owned by the Government Building Agency.
Winter
monitoring

Design:
 Architect: ir. Ruurd Roorda, Government Building Agency, NL.
 Daylight concept: Esbensen, DK.
 Energy concept & natural ventilation: W/E consultants, NL.
 Building physics: Peutz & Associes, NL.

This building is an EC2000 project, and is very energy efficient (17 m3/m2
gas equivalent of primary energy use) as a result of integrated design. The
aim was to eliminate the need for mechanical ventilation and give
occupant the maximum possible control of the indoor climate. Key issues
are: optimal use of daylight, passive ventilation, cooling by night ventilation,
low energy use and use of sustainable building materials.
Tax Office of
Enschede
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Building presentation
typical floor plan (1st floor)
Tax Office of
Enschede
N
Presentation
of the building
Square
Monitoring
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Cellular offices
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ATRIUM
Storage
of files
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Connection to
old building
Cellular
offices
Meeting
room
Storage
of files
corridor
Cellular
offices
Street +
Railway
Meeting
room
Cellular offices
Typical floor plan
Building presentation
cross section & view of the atrium
Tax Office of
Enschede
Presentation
of the building
N
Cross section
Monitoring
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Cellular Storage ATRIUM
office
of files
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Internal solar
protection
Upward view of atrium
Building presentation
view of the atrium & rear façade
Tax Office of
Enschede
Rear façade
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Downward view of atrium
Building presentation
ventilation installation
Tax Office of
Enschede

based on the stack effect of the
atrium (see schematic on next slide
...).
Presentation
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Monitoring
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Extraction chimneys
on the roof
Concept: The ventilation system is

Installation:
Winter
monitoring

Fresh air enters the building via
the trickle vents in the office.
Summer
monitoring

The air passes to the atrium via
acoustic ducts in the false ceiling.
Conclusions

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
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The air leaves the building via
the roof of the atrium (by natural
means).
Fan-assisted:
If the wind velocity is less than 2 m/s,
fans are switched on to help the stack
effect in the atrium.
Fans for suppl.
ventilation
Building presentation
ventilation concept - stack effect
Tax Office of
Enschede
Acoustical ducts
in false ceiling
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Trickle
vents
Building presentation
ventilation components
Tax Office of
Enschede
The two constant flow trickle vents are situated just below the exposed ceiling. The incoming cold air
sticks to the ceiling by the Coanda effect and is mixed with the warm indoor air before it falls into the
office space, witch prevents draughts from causing comfort problems.
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The settings of the
trickle vents are
clearly marked:
0: all closed
1: 1 open
2: 2 open
2 Trickle vents in
each office
Remark: The trickle vents
have very high acoustical
performances (railway in
front of the building). They
are also pressure
independent: within a
certain range, they give the
same flow at different
pressures (see next
slide...)
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Extraction opening
of the acoustic
duct in the office
Building presentation
pressure independent vents
Flow Q (m³/h)
Tax Office of
Enschede
Presentation
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Summer
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Pressure
dependent vent
Pressure
independent vent
Q design
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Pressure difference range
Pressure difference:
Dp (Pa)
Pressure independent vents give
a constant flow within a range of
pressure differences.
Building presentation
offices
Tax Office of
Enschede
Presentation
of the building
Monitoring
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Winter
monitoring

Besides the ventilation devices, the offices have other features
which improve the indoor climate:
 External blinds on the South façade to reduce the solar
gains and avoid overheating.

A shelf beneath each window reflects the daylighting
windows reflects the light deep in the room and so
improves the light distribution. A high frequent light system
keeps the light level at 500 lux.

The offices have a lot of exposed thermal mass in the
ceilings and tiled floors. Therefore acoustic panels have
been installed in the offices to reduce reverberation.
Summer
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All these techniques are presented on the following schematic…
Building presentation
offices
Tax Office of
Enschede
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Building presentation
shading device on the South façade
Tax Office of
Enschede
Trickle
vents
Presentation
of the building
Daylighting window
Daylight
shelf with
integrated
lights
Monitoring
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Daylighting window
Winter
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Internal view - open
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Internal view - closed
External view
Light shelves are automatically
controlled by a solar radiation
sensor, but it can be manually
overruled
Building presentation
the building strategy
Tax Office of
Enschede
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
A desk map gives very clear instructions to the occupants how to use the
different devices in winter & summer (see next slide ...)
In the winter:

Ventilation:

during OH: position 1 (for Indoor
Air Quality)

outside OH: position 0 (to reduce
ventilation losses)

Heating:

during OH: choose adequate
level

outside OH: keep chosen level

Lighting

during OH: on, if necessary

outside OH: off

External shading:

during OH: control freely

outside OH: automatic control
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In the summer:

Ventilation:

during OH: position 1 or 2 (for
Indoor Air Quality & intens. vent.)

outside OH: position 2 (intensive
night ventilation)

Heating:

during OH: choose adequate
level

outside OH: keep chosen level

Lighting

during OH: on, if necessary

outside OH: off

External shading:

during OH: control freely

outside OH: automatic control
Desk map with
user instructions
ventilation
Winter
Tax Office of
Enschede
Presentation
of the building
During office hours
Monitoring
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Winter
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Outside office hours
Summer
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Summer
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During office hours
Outside office hours
Internal
shading
External
shading
lighting
heating
Monitoring
the monitoring scheme - 1997
Tax Office of
Enschede

A winter (April) and summer
(September) survey was
organised.

In April the Coanda effect was
determined in rooms 111,
121, 314, 320, 503 and 520;
the CO2 levels were
measured in rooms 105, 123,
505 and 518.

In June and July summer
ventilation rates and CO2
levels were monitored in
rooms 107, 122, 311, 322,
505 and 520.

The whole year the indoor
temperature was monitored.
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Winter monitoring
questionnaires
Tax Office of
Enschede

170 questionnaires were distributed. 102 are returned. Of the respondents
20% are female and 80% male, the average age is 42 years.

Main results:
 They showed that temperatures in the offices were good, with enough
possibilities to control it.
 Air movement was reported to be either ‘adequate’ or ‘too high’.The
amount of control available to the occupants was either acceptable or
good.
 Air quality was ‘adequate’ and humidity either ‘good’ or to ‘low’.
 Unpleasant odours from cigarette , office equipment and diesel fumes
were considered to ‘acceptable’ by 75% of the respondents and ‘not’
acceptable by the remaining 25%.
 96% are pleased with the daylighting, 58% complain about glare
 99% have sufficient artificial light, 88% have control over the light
levels
 The noise level is ‘good’ to ‘satisfactory’ -10% of the interviewees
persons have problems with the noise.
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Winter monitoring
the Coanda effect
Tax Office of
Enschede
Presentation
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Winter
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Summer
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The Coanda effect causes the flow of cold air to stick to the ceiling for a long
enough period for it to mix with the warm indoor air before it falls into the
space below. This prevents discomfort from draughts.
The table below shows the number of times this phenomenon was detected
and the distance travelled by the cold air before it fell into the space
bellow.
The only room in which the Coanda effect was not noticeable was number
503 on the South façade of the 5th floor.
Conclusions
Room
Façade
Floor
More
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111
121
314
320
503
520
South
North
South
North
South
North
1
1
3
3
5
5
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Coanda
Effect
yes
Yes
Yes
Yes
No
Yes
Distance
[m]
2.00
2.00
1.20
1.50
0.80
Courtesy W/E consultants
Winter monitoring
ventilation
Tax Office of
Enschede
Presentation
of the building
Monitoring
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Winter
monitoring
Summer
monitoring
In the winter only one trickle vent is open. The aim is to get a ventilation flow of
100 m3/h (2 ach).
The table below shows the results of experiments carried out on April 16th.
During the period monitored, the wind was from the North with a velocity of
2 m/s. The outdoor temperature was 10°C. These values are close to the
design conditions for the building.
Air flow rates measured on the 3th and 5th floors are within 10% of each other;
air flow rates on the 1st floor are rather high due to some construction
problems. These problems have since been resolved.
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Room
111
121
314
320
503
520
Façade
South
North
South
North
South
North
Floor
1
1
3
3`
5
5
Vent [m3/h]
(160)
(126)
90
96
110
97
Courtesy W/E consultants
Winter monitoring
CO2 concentration level
Tax Office of
Enschede
CO2 concentration level in April - during office hours
Presentation
of the building
200
Monitoring
set-up
160
Summer
monitoring
Room 107 - S
Room 123 - N
140
[hours]
Winter
monitoring
180
120
Room 505 - S
100
Room 518 - N
80
60
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40
20
0
0- 300
300-600
600-900
900-1200
1200-1500
1500 and up
CO2 concentration level [ppm]
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The outdoor CO2 concentration level is 350 ppm. Values less than 350 ppm are due
to the accuracy of the measurement apparatus that is used. The CO2 concentration
levels found in the rooms are well below the maximum level of 1500 ppm; even CO2
concentration levels of 1200 ppm are very rare.
Summer monitoring
questionnaires
Tax Office of
Enschede

Presentation
of the building

Of the 170 questionnaires that were distributed, 105 were returned. 19% of
the respondents were female and 81% male, the average age was 42 years.
The survey was held in September, just after the ‘heat wave’ in August which
clearly influenced the results.
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monitoring

Summer
monitoring
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Main results:
 The temperature on the workplace were ‘very hot ‘, control ‘bad’, very
little ventilation with ’bad’ ventilation control, although control of draughts
was adequate.
 The air quality is ‘satisfactory’ and the humidity ‘good’.
 50% experience ‘smelly’ air, 60% blames this on the nearby railway
station; for 55% this was acceptable and for 45% not acceptable.
 99% were ‘satisfied’ with the illumination, 3% wanted more light, 94%
could sufficiently control the day lighting, 35% had some problems with
glare on their computer screen.
 98% had sufficient electric light and can control it.
 Although the noise level was acceptable, 12% had problems with it.
Summer monitoring
hot period in the summer
Tax Office of
Enschede
Monitoring
set-up
Winter
monitoring
Summer
monitoring
31
Temperature [°C]
Presentation
of the building
33
Text.
29
Tatrium
27
25
23
T room123,North
21
T room127, South
19
17
Conclusions
15
0:00
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12:00
0:00
12:00
0:00
12:00
0:00
12:00
0:00
Time in hours / 11 to 14 August
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Due to the external venetian blinds on the south façade and the use of night cooling the
internal temperatures are never higher than 28°C during a hot period (Text. = 32°C)
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Summer monitoring
Night ventilation
Tax Office of
Enschede
Presentation
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

Monitoring
set-up
The average long term ventilation flow during the last two weeks of July w
has been determined in rooms 107, 122, 505 and 520 with the PFT-method.
A different tracer gas was used in each room. The gas concentration was
measured at different locations in the rooms. Based on these results the
ventilation rate was determined.
Winter
monitoring
Summer
monitoring

For night time ventilation cooling a minimum ventilation rate of 4 ach or 200
m3/h per room is required. The occupants are instructed to open both trickle
vents when they go home (= setting 2).

The results are:
 The average summer night ventilation rate is 3.75 ach, the aim is 4 ach.
 The rooms are flushed very well; there are no ‘dead angles’ with higher
concentrations.
 Leaks between adjacent rooms are small (average 2 -8 m3/h, max. 40
m3/h in the lower floors and the N-room of the fifth floor).
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Summer monitoring
CO2 concentration level
Tax Office of
Enschede
CO2 concentration level in June - during office hours
Presentation
of the building
200
Monitoring
set-up
Summer
monitoring
[hours]
Winter
monitoring
180
160
Room 107 - S
140
Room 123 - N
120
Room 505 - S
Room 518 - N
100
80
60
Conclusions
40
20
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0
0- 300
300-600
600-900
900-1200
1200-1500
1500 and up
CO2 concentration [ppm]
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The CO2 concentration level during working hours in the summer were measured in June.
These results differ not much from the CO2 level in the winter. The outdoor CO2
concentration level is 350 ppm. Values less than 350 ppm are due to the accuracy of
the measurement instrument. The CO2 concentration levels found in the rooms are
well below the maximum level of 1500 ppm.
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Summer monitoring
Weighted temperature exceeding hours
Tax Office of
Enschede

Presentation
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Monitoring
set-up
Winter
monitoring
Summer
monitoring
Conclusions

ISO 7730 describes a method for
the evaluation of the internal
summer comfort: This is the
method of weighted exceeding
hours. All hours with a
temperature above 25°C are
taken into account. High
temperatures have a higher
weighting factor:
Temperature weighting factor

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



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

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25°C:
26°C:
27°C:
28°C:
29°C:
30°C:
1.0
1.4
2.0
2.6
3.4
4.2
The allowable norm weighted
temperature exceeding is 150
degree hours.

Based on the monitored indoor
temperatures in 1997, 166
degree hours were calculated.

These results are not corrected
for unintended accidents (opening
the windows when it is very hot,
cleaning the sun shades during hot
summer days, operating the boiler,
etc).

When corrected, the exceeding
is 86 degree hours: the
internal summer comfort can be
considered as acceptable
Conclusions - 1
Tax Office of
Enschede

Natural ventilation:
 The average winter ventilation rate is 2 ach, which was the design
intention.
 Summer night time ventilation rate is 3.75 ach.
 Indoor Air Quality: The CO2 levels in summer and winter are always
below the maximum value of 1500 ppm. IAQ is of an acceptable
standard.
 The Coanda effect was investigated and it was only in the most
unfavourable room, situated on the fifth floor on the lee of the building
that this phenomenon was not detected. In all the other rooms it
functions well and there are no draught problems.

Overall conclusion:
the concept of natural ventilation with constant flow trickle vents, acoustic
ducts to the atrium and auxiliary fans in the exhaust openings operates
well.
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Conclusions - 2
Tax Office of
Enschede

Presentation
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Cooling by natural ventilation (Night cooling)
 The ventilation rate for cooling (3,75 ach) is close to the desired value
of 4 ach. Higher cooling effects can be obtained if the auxiliary fans
are switched on earlier.
 Indoor temperatures are sometimes higher than would normally be the
case because of operator error: (the boiler was switched on in the
summer, several sunny days the sun shades were moved so that
windows could be cleaned and windows were left open on days when
outside temperature was higher than indoor temperature, etc.).
 There were complains about summertime temperatures, but a heat
wave in august had a significant influence on the findings.
 The uncorrected weighted temperature exceeding is 166 hours for
1997 (an extreme hot year). This value is slightly higher than the limit
value of 150 (for a normal year). However when one takes into
account operating errors , the value can be lowered to 86 hours.
Hence the summer comfort levels can be within acceptable limit if
mistakes are avoided.
Concluding remarks and
acknowledgement
Tax Office of
Enschede
Presentation
of the building

Monitoring
set-up
Concluding remarks
This concept shows that the integral approach of natural ventilation,
effective solar shading, daylight control and the use of thermal mass for
heat accumulation leads to a successful application of natural ventilation.
Winter
monitoring
Summer
monitoring
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Acknowledgement
We thank the Government Building Agency, East Directorate,
Arnhem, NL, and W/E consultants sustainable building, Gouda,
NL, who has performed the monitoring, to allow us to make use of
the data (W/E report 5089.2, March 1998) and pictures.
More information...
Tax Office of
Enschede
Presentation
of the building
Monitoring
set-up
Winter
monitoring
Summer
monitoring
Conclusions
Find more information on the PROBE building in the following documents:
\Reports \Monitoring Reports \Summary Reports\nl3summ.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\nl3det.pdf
 detailed reports of all 19 monitoring campaigns (20p./campaign)
 contents: monitoring set up - analysis of results - conclusions
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You can read and print pdf-files with the Acrobat® Reader
®3.0. Program. This program is free.
Download it from the Acrobat web site: www.adobe.com OR
run the installation file ar32e301(1).exe in the directory
\Installation