lēzenu jumtu risinājumi ziemeļvalstu klimatos
DESCRIPTION
2011. gada 20. oktobrī Rīgā notika starptautisks seminārs „Daudzdzīvokļu māju kvalitatīvas renovācijas priekšnosacījumi”. Pasākumā piedalījās lektori no Vācijas, Somijas un Latvijas. Pasākuma laikā m.cs. Jyri Nieminen (VTT Somijas Zinātniski pētnieciskais centrs (Somija)) stāstīja par lēzenu jumtu risinājumiem ziemeļvalstu klimatos. Video skaties http://vimeo.com/33707969 vai youtube.com/siltinamTRANSCRIPT
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How to ensure high performance in large well insulated roofs
Jyri NieminenKey Account ManagerVTT Technical Research Centre of Finland
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218.10.2011
Climate change
Possible long-term changes in climate in the North
Average temperature increasesPrecipitation in winter increasesCloudiness in winter increasesSnowfall decreases
ConsequencesRain load on buildings increaseConditions for mould growth increasePossibility of rain leaks increase
Hygrothermal quality requirements!Climate change increases the moisture risk level in all buildings
Yearly average rainfall in Finland according to different scenarios
Cha
nge
(%)
Source: The Finnish Meteorological Institute (FMI)
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318.10.2011
Amount of moisture
Rain, with 1% of rain leaking in.
Normal and worst case gives big variation
Reason for moisture g/m2hRain 0,65 – 2,40
Diffusion 0,002Air leakage 0,036 – 5,20Built-in moisture 0 – 0,300TOTAL 0,688 – 7,902
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418.10.2011
Moisture in building structures
Moisture damages are one of the main cause bad indoor air qualities and they affect the occupants´ health and comfort.
Moisture is the main cause of deterioration of building materials and structures
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518.10.2011
Ventilated roof: Scope of application
“To ensure the drying of built-in moisture, and ensure a proper performance of the roof by minimizing the moisture risks during the life-circle of the roof”.
No mechanical ventilation is neededPre-requisitions for performance:
Design and construction made according to guidelinesMaterials, construction methods and work supervision are carried out according to good workmanship.
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618.10.2011
Ventilated roof
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718.10.2011
Openings
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818.10.2011
Performance of the grooves
Micro climate around the building is the main driving force for the groove ventilation. Air speed 0,01 – 0,10 m/s.The air flow direction in the grooves is not constant but changes according to changes in the pressure field.
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918.10.2011
Vapour barrierHousing, offices and commercial buildings: Low indoor humidity in winter
< 50 %Water vapour resistance 500-1000 m2 s Pa/kg
Schools, sports halls, process industry: Medium indoor humidity in winter > 50 %
Water vapour resistance 1000-2000 m2 s Pa/kg
Swimming halls, pulp industry: Extreme conditions in winter especially below roof > 80 %
Water vapour resistance 2000-10000 m2 s Pa/kg
Vapour barrier can be , e.g., a bitumen membrane or rubberized bitumen membrane, or product with vapour resistance 500 x109 m2 s Pa/kg, minimum
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1018.10.2011
Roof ventilation and heat losses
t > 200 mm: + 2%
= 0,001 W/m K
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1118.10.2011
Drying potential, cold continental climate
Katto 10 m, tuuletettu 0.1 m3/m2h
-0,05
0,00
0,05
0,10
0,15
0 90 180 270 360 450 540 630 720
Kuivuminen, kg/h
168 per. Mov. Avg.(Kuivuminen, kg/h)
0 720
Dagar från Jan. 1
Utto
rkni
ngsh
astig
het,
kg/h
10 x 1 m2 Tak, ventilering 0,1 m3/m2 h
Flytande medelvärde
Days from January 1
Floating average
10 x 1 m2 roof, ventilation 0,1 m3/m2 hD
ryin
g ra
te k
g/h
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1218.10.2011
0
10
20
30
40
50
60
70
80
90
0 100 200 300 400 500 600 700 800
Tid [d]
Drying through ventilation
Tota
l moi
stur
e, k
g
Time, days
Example:
40 m2 of wet roof due to rain during installation
Average moisture 10 % of weight corresponding to 2 kg/m2
Drying through ventilation, start January 1
Outcome in practise
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1318.10.2011
Ventilation design step by step
Identify type of use for the building
Identify outdoor conditions
Identify the roof ventilation conditions
Identify roof type and required U-value Choose of roof combination slabs, thicknesses of:- Top layer - Grooved layer - Middle layer- Bottom layer
Step 1
Step2
Step 3
Step 4
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1418.10.2011
Design step by step, continued
Define moisture conditions and required ventilated rate
Define Ventilated area
Define Dimensions for a ventilated area
Step 5
Step 6
Step 7
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1518.10.2011
Indoor air humidity in winter
Example of buildings Indoor climate type, humidity in winter
Warehouse Dry; < 30 %Shopping centre Low; < 40 %Housing Average; < 50 %Office Average; < 50 %Process industry, sport halls High; > 50 %Swimming hall, pulp industry Extreme; > 80%
Step 1
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1618.10.2011
Types of outdoor conditions
Climate type LocationsCold continental Kiruna, Jyväskylä, Rovaniemi,
MoscowMild continental Kiev, Minsk, Warsaw, RigaCold maritime Helsinki, St Petersburg,
Stockholm, TallinnMild maritime Copenhagen, Gothenburg
OsloRainy maritime Bergen
Step2
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1718.10.2011
Total maximum moisture load
Calculated moisture load for dimensioning:
Climate Total moisture load;kg/m2
Average moisture load; g/m2/h
Cold Continental 7,5 0,86Mild Continental 6,5 0,74Cold maritime 6,5 0,74Mild maritime 5,7 0,65Rainy maritime 8,2 0,94
Step 2
Source: RESEARCH REPORT No VTT-R-03394-06
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1818.10.2011
Roof ventilation conditions
Groove ventilation conditions
Open or low density area
Dense-developed area
Windscreen by topography or forest
Excellent 1 level roof, some obstructing structures
1 level roof, without obstructing structures
Forest high building, 1 level roof without obstr. struct.
Good 1 level roof with obstr. struct.
1 level roof, some obstr. struct.
1 level roof without obstr. struct.
Fair Roof in 2 or more levels
1 level roof with obstr. struct.
1 level roof, some obstr struct.
Poor Roof in >2 some obstr. struct.
Roof in > 2 levels 1 level roof with obstr. struct.
Step 3
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1918.10.2011
U-values and thicknesses
Rmembrane = 0.04 m2K /W; Rsi + Rse = 0.14 m2K /Wboard = 0.039 W/m K; slab = 0.037 W/m K with grooves
U-value Total thickness
Bottom layer
Middle layer
Grooved layer
Top layer
0,10 360 60 140 140 200,11 330 50 120 140 200,12 300 60 120 100 200,13 280 60 100 100 200,14 260 60 80 100 200,15 240 60 80 80 20
Step 4
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2018.10.2011
Build up of the roof
Alternative 1 Vapour/air barrier
Bottom layer
Middle layer Grooved layer
Top layer Roofing
Bitumen membrane
30 -160 mm 30 - 160 mm 100 -160 mm 20 - 30 mm According to design
Alternative 2 Bottom layer
Vapour/Air barrier
Middle layer Grooved Top layer Roofing
20 - 50 mm Bitumen membrane
30-160 mm 100 -160 mm 20 - 30 mm According to design
Recommended thicknesses of insulation layers from bottom to top
Step 4
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2118.10.2011
Define moisture and required ventilation rate
Cold continental climate
Step 5
0,05
0,1
0,15
0,2
0,25
0,3
0,35
150 200 250 300 350 400
Req
uire
d ve
ntila
tion
rate
, l/m
2 s
Insulation thickness, mm
Cold continental climate
Extreme conditions: pulp industry, swimming hall
Dry conditions: warehouse, dry spaces
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2218.10.2011
Define ventilated area
0,000
0,050
0,100
0,150
0,200
0,250
0,300
0,350
60 80 100 120 150 200
Ventilated area, m2
Req
uire
d ve
ntila
tion
dm3 /s
m2
Maximum for a sunny roof
Good ventilation conditions
Step 6
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2318.10.2011
Other Ventilation conditions
Step 6
0,000
0,050
0,100
0,150
0,200
0,250
0,300
0,350
60 80 100 120 150 200
Ventilated area, m2
Req
uire
d ve
ntila
tion
dm3 /s
m2
Maximum for a sunny roof
Very good ventilation conditions
0,000
0,050
0,100
0,150
0,200
0,250
0,300
0,350
60 80 100 120 150 200
Ventilated area, m2
Req
uire
d ve
ntila
tion
dm3 /s
m2
Maximum for a sunny roof
Fair ventilation conditions
0,000
0,050
0,100
0,150
0,200
0,250
0,300
0,350
60 80 100 120 150 200
Ventilated area, m2
Req
uire
d ve
ntila
tion
dm3 /s
m2
Maximum for a sunny roof
Poor ventilation conditions
0,000
0,050
0,100
0,150
0,200
0,250
0,300
0,350
60 80 100 120 150 200
Ventilated area, m2
Req
uire
d ve
ntila
tion
dm3 /s
m2
Maximum for a sunny roof
Low ventilation conditions
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2418.10.2011
Define ventilated area
Ventilated area = a x b;a =distance between
hoodsb = distance between
connecting grooves
Step 7
Roof vent
Connection groove Ventilatedarea
Ventilatedarea
Slope
ab
Slope
Drainage
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2518.10.2011
Suggested length of ventilated areaIndoor climate type
Roof characteristics
Open areaNo solar,
m
Open area Solar,
m
Shady area
No solar, m
Shady area
Solar, m
Dry,Ware house
1 levelLarge roof
20 20 20 20
Average humidity Offices, schools
Moderate area several levels
15 - 20 20 10 - 15 15 - 20
Extreme humidity Swim hall
Large roof, High building
< 10 10 - 15 < 10 10 - 15
Step 7
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2618.10.2011
Conclusions/Suggestions
Moisture can be calculated Air leakage is the main problemAverage ventilation guarantee dryingDesign based on required air flow rateMaximum length is set depending on available wind conditions
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2718.10.2011
Thank You!