1. Air flow rates in residential buildings
Marianna Luoma

2. Designing the air flow rates in residential buildings
Determine the supply air flow rates in dwelling areas
Determine the extract air flow rates
Check that
Air change rate is at least 0,5 1/h or 0,35 dm3/s,m2, but not more than 1,0 1/h
Total extract air flow rate is about 5% higher than total supply air flow rate; increase the exctract air flow rates if necessary
Design the boosting air flow rates and the air flow rates for the situation when the residence is not occupied

3. Designing the supply air flow rates
Aim at 6 l/s,person or 0,5 1/h or 0,35 l/s,m2
Bedrooms are designed for two persons
Bedrooms can be adjusted for one person, when the end-use is known
The living room may ”borrow” supply air from the bedrooms

4. Designing the extract air flow rates
Use the extract air flow rates given in the Table in the Appendix 1 in D2
Make sure, that extract is about 5% higher than supply air flow rate
In the normal case, emphasize the extract from bathroom and toilet
A separate exhaust at the cooker hood is recommended
An air flow rate of 40…50 l/s is needed at the cooker hood to remove the smell from cooking activities

5. Air flow rates in the case of boosting and absence
Boosting air flow rate of +30 % for the whole dwelling
Not just through the cooker hood, but the extract from the bathroom and toilet and cleaning situation are more important
Sound level may increase 10 dB, if the resident has the possibility to control the boosting
When the occupants are away for a longer period of time, the air flow rates may be dropped with 60%

6. Design exercise 1 Design air flow rates for one-room flat (31 m2)
In this case:
The boosting of air flow rate can be controlled separately for each dwelling
Room height is 2.6 m

7. An example of air flow rates in a small apartment (31 m2)
1 room + kitchen + sauna
31 m2
Dwelling
Sauna
Bath-
Kitchen
Σ Supply
Σ Extract
Air change
Extract + Supply
area
room
(L/s)
(1/h)
D2 Table values
D2 Boosting 30 %
D2 Absence

8. smaller than extract air flow rate. You need to increase the supply.
1 room + kitchen + sauna
31 m2
Dwelling
Sauna
Bath-
Kitchen
Σ Supply
Σ Extract
Air change
Extract + Supply
area
room
(L/s)
(1/h)
D2 Table values
 +12
 ±6
 -10
 -8
 -18
 0,8
-6 
D2 Boosting 30 %
 +15,6
±7,8 
 -13
-10,4
-23,4   1
-7,8 
D2 Absence -60 %
 +4,8
±2,4 
-4 
-3,2 
 -7,2
0,3 
-2,4 
Supply is flow rate is 33%
smaller than extract air flow rate.
You need to increase the supply.

9. Design exercise 2 Design air flow rates for two-room flat (63 m2)
In this case:
The boosting of air flow rate can be controlled separately for each dwelling
Room height is 2.6 m

10. 2 rooms + kitchen + sauna 63 m2 Bed- Living Cloak Sauna Bath- Kitchen
ΣSupply
ΣExtract
Air
SSupply+SExtract
room
change
(L/s)
(1/h)
D2 Table
 +12
 +10
values
D2 Design
D2 Boosting
30 %
D2 Absence -60 %

11. STEP 1 2 rooms + kitchen + sauna 63 m2 Bed- Living Cloak Sauna Bath-
ΣSupply
ΣExtract
Air
SSupply+SExtract
room
change
(L/s)
(1/h)
D2 Table
+12
+10 -3 ±6
-10 -8
+22
-21
0,5 1
values
D2 Design
D2 Boosting
30 %
D2 Absence, -60 %

12. STEP 2 2 rooms + kitchen + sauna 63 m2 Bed- Living Cloak Sauna Bath-
ΣSupply
ΣExtract
Air
SSupply+SExtract
room
change
(L/s)
(1/h)
D2 Table
+12
+10 -3 ±6
-10 -8
+22
-21
0,5 1
values
D2 Design
-14
-27
0,6 -5
D2 Boosting
30 %
D2 Absence, -60 %

13. STEP 3 2 rooms + kitchen + sauna 63 m2 Bed- Living Cloak Sauna Bath-
ΣSupply
ΣExtract
Air
SSupply+SExtract
room
change
(L/s)
(1/h)
D2 Table
+12
+10 -3 ±6
-10 -8
+22
-21
0,5 1
values
D2 Design
-14
-27
0,6 -5
D2 Boosting
+15,6
+13
-3,9
±7,8
-13
-18,2
+28,6
-35,1
0,8
-6,5
30 %
D2 Absence, -60 %

14. STEP 4 2 rooms + kitchen + sauna 63 m2 Bed- Living Cloak Sauna Bath-
ΣSupply
ΣExtract
Air
SSupply+SExtract
room
change
(L/s)
(1/h)
D2 Table
+12
+10 -3 ±6
-10 -8
+22
-21
0,5 1
values
D2 Design
-14
-27
0,6 -5
D2 Boosting
+15,6
+13
-3,9
±7,8
-13
-18,2
+28,6
-35,1
0,8
-6,5
30 %
D2 Absence, -60 %
+4,8 +4
-1,2
±2,4 -4
-5,6
+8,8
-10,8
0,2 -2