malya abdelouhaba,b, bernard collignan , francis allard abdelouhab_cstb.pdf · malya abdelouhaba,b,...
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Malya ABDELOUHABa,b, Bernard Collignana, Francis Allardb
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Solils
Sediments and Water, Paris. PAGE 1
Passive Sub-slab Depressurization System in
building, against volatile soil contaminants
a: CSTB- Centre Scientifique et Technique du Bâtiment- FRANCE
b: LEPTIAB- Université de La Rochelle - FRANCE
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Plan
Introduction
Presentation of experimental dwelling
Study of Passive S.D.S.
Protocol
Results and discussions
Conclusion
PAGE 2
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Introduction (1/3)
PAGE 3
2
3
1
2
3
44
cracks
joints between walls
pipeline networks
Convection
Diffusion
34
12
1
Underground sources: contaminatedsoil or groundwaterSource CSTB
P+
P- P+
Tout<Tin
Vadose zone
Chemical vapor migration
walls
How to prevent the building against entry of the volatile soil contaminants ?
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Introduction (2/3)Active S.D.S.
PAGE 4
Well know technology for more than twenty years in radon building protection
Fan
Depressurized zone
Active S.D.S. is one of the most effective methods of lowering volatile soil contaminants levels
P -
P- -
P +
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Introduction (3/3)Passive S.D.S.
PAGE 5
Thermal buoyancy + wind effect Passive S.D.S.
Ability and efficiency of Passive S.D.S. to maintain the depressurization of the basement : one year follow-up
To study hybrid solutions for basement depressurization using a stato-mechanical extractor
Fan
Depressurized zone
Wind
Tout< Tin
P-
P+
P- -
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Presentation of experimental dwelling (1/3)
PAGE 6
MARIA: Mechanized house for Advanced Research on Indoor Air
To study relations between ventilation and indoor air in housing sector
Preliminary experiments
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Presentation of experimental dwelling (2/3) Installation of S.D.S.
PAGE 7
Installing S.D.S. during the construction 10 holes managed through concrete slab to
measure pressure
Gravel
Slab
Memebrane
Sumps
10 holes drilled through the concrete slab to measure pressure
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Presentation of experimental dwelling (3/3) Characterisation of basement permeability
PAGE 8
P
PFan
Inhabited volume
Preliminary experiments
10
100
10 100
Basement exhaust flow (m3/h)
Basement depressurisation (Pa)
hole1 hole2
hole3 hole4
hole5 hole6
hole7 hole8
hole9 hole10
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (1/9)Adaptation of basement
PAGE 9
Preparation of basement : need to install a new sump with 200 diameter
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (2/9) Experimental protocol
PAGE 10
- Wind (velocity and direction)- External temperature
- Internal temperature
- Duct air velocity- Duct temperature
Basementdepressurisation:
P
Basic extractor
Stato-mechanical extractor
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (3/9)Monthly Results
Figure 1: Evolution of basement extract flow and basement depressurization during time
High variability of running during a day natural forces highly variables
Flow rate rises the depression of the basement also rises
0
5
10
15
20
25
30
0
10
20
30
40
50
60
5/3 10/3 15/3 20/3 25/3 30/3
Pam3/h basement extract flow basement depressurisation
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (4/9)
Monthly Results
Figure 2: Comparison of basement extract flow function of basement depressurization for natural and mechanical extraction
The difference of the slopes is due of the Installation of the centred sump
Basement depressurization is
always homogenous
1
10
100
0 1 10 100
Q (m3/h)
DP (Pa)
Natural extraction Mechanical extraction
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (5/9)Annual Results
Figure 3: Monthly averaged temperature difference between air duct and external air and monthly averaged wind force along year
Thermal and wind forces induce the extracted air flow rate from the basement.
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
0
2
4
6
8
10
12
14
j a s o n d j f m a m j
m/s°C
Monthly averaged (Tduct-Text)
Monthly averaged wind force
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (6/9)Annual Results
Figure 4: Percentage of running time of the system along year above three thresholds
Significant percentage of running along year and mainly during winter season
Efficiency is better from March installation of static extractor
0
10
20
30
40
50
60
70
80
90
100
j a s o n d j f m a m j
% Qextr. > 13,5 m3/h (1 Pa)
Qextr. > 19 m3/h (2 Pa)
Qextr. > 23 m3/h (3 Pa)
Installing static extractor
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (7/9) Effect of static extractor
Figure 5 : Comparison of extract flow from basement function of wind velocity for system with static extractor and with basic extractor (temperature difference < 4°C)
y = 0,96x1,99
y = 0,44x2,07
0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5 6 7 8
m3/h
m/s
with static extractor with basic extractor
power law (with static extractor) power law (with basic extractor)
Relative dispersion of experimental points obstacles around a dwelling (trees, other buildings)
Extract flow with static extractor is around twice the value of extract flow with basic extractor
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (8/9)
Effect of the mechanical operation of the extractor
PAGE 16
Gravel
Slab
Memebrane
Sumps
10 holes drilled through the concrete slab to measure pressure
Hybrid solutions
Fan on
Maximum power (20- 25 W) 03/06/2008 at 1pm30
Medium power (10- 15 W) 06/06/2008 at 1pm30
Minimum power (2- 4W) 09/06/2008 at 1pm30
Mechanical operation of the extractor for three regimes
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Study of passive S.D.S. (9/9)
Effect of the mechanical operation of the extractor
Figure 6 : Time evolution of wind force, temperature difference between the air duct and the outside and airflow extracted from the basement for three regimes of
mechanical operation of the extractor (Maximum, Medium, and Minimum)
Natural forces are negligible the mechanical running ensures a flow of minimum extraction
0
5
10
15
20
25
30
35
40
45
50
-6
-4
-2
0
2
4
6
8
10
12
3/6 4/6 5/6 6/6 7/6 8/6 9/6 10/6 11/6 12/6 13/6 14/6
m3/h°C m/s Wind force (Tgaine-Text) Extracted flow
P minP max P med
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Conclusion
The natural running of S.D.S. is highly variable along the year but percentage of running time could be significant and mainly during winter season
Using two different extractors: a basic one and other with shape optimised to benefit of the impact of wind on extraction flow ‘static extractor’
Natural forces are insufficient use of an optional mechanical operation of the static extractor can generate a minimum rate of extraction
Advantage of passive S.D.S.: Protect the building against volatile soil contaminants
This system is a low cost of operation and it requires low maintenance
PAGE 18
16-19 March, 2010 | INTERSOL2010: 9th International Conference-Exhibition on Soils
Sediments and Water- Paris |
Thank you for your attention
PAGE 19