1. Heating Losses- Infiltration and Ventilation
ARCH-432

2. Attendance
Which civilization made it a point to layout whole cities to take advantage of passive heating? In what direction did the city streets run?
Greece
Rome
Egypt
Persia
Babylonia
The ancient Greeks did this. Shown is Priene (5th Century B.C.), which has all of the streets laid out in an East-West fashion, thus allowing all homes to point South.

4. Attendance
The ancient Greeks did this. What was shown is Priene (Priēnē); (5th Century B.C.), which had all of the streets laid out in an East-West fashion, thus allowing all homes to point South.
The ancient Greeks did this. Shown is Priene (5th Century B.C.), which has all of the streets laid out in an East-West fashion, thus allowing all homes to point South.

5. Attendance “Only primitives and barbarians lacked
knowledge of houses turned to face the
winter sun, dwelling beneath the ground like swarming ants in sunless caves.”
Aeschylus
Ess ca less
One of the earliest writer of Greek tragedy – before him plays had single actors who could only respond to a chorus (group of people). Aeschylus increase the tragedy to two actors with dialog.

6. Greetings
Capt. Kirk
Aeschylus

7. Attendance Aeschylus pronounced Ess ca less
One of the earliest writer of Greek tragedy – before him plays had single actors who could only respond to a chorus (group of people). Aeschylus increase the tragedy to two actors with dialog.

8. Big Picture Moment roof Infiltration and Ventilation Ceiling Partition
Exterior
wall
Glass
conduction
Floor
Infiltration and Ventilation
Ceiling
Partition
I. Heat Loss
A. Five main types of heat loss
1. Transmission (conduction)
2. Infiltration (convection)
3. Ventilation (convection)
4. Radiation (radiation)
5. Moisture migration

9. Five main types of heat loss 1. Transmission (conduction)
roof
Exterior
wall
Glass
conduction
Floor
Infiltration and Ventilation
Ceiling
Five main types of heat loss
1. Transmission (conduction)
2. Infiltration (convection)
3. Ventilation (convection)
4. Radiation (radiation)
5. Moisture migration
I. Heat Loss
A. Five main types of heat loss
1. Transmission (conduction)
2. Infiltration (convection)
3. Ventilation (convection)
4. Radiation (radiation)
5. Moisture migration

10. Summary of Heat Losses Wall Roof Floor Windows Doors Infiltration
Ventilation
Envelope Losses

11. What You Need To Know
The difference between ventilation and infiltration
Calculation methods for both ventilation and infiltration

12. What You Need To Be Able To Do
Calculate infiltration/ventilation loads
Be able to reduce/mitigate infiltration and ventilation loads
Employ techniques for increasing ventilation effectiveness

13. Terms Infiltration Exfiltration Ventilation
Direct Outside Air System (DOAS)

14. Infiltration
“The uncontrolled introduction of outside air into a building.”
I. Infiltration
A. The uncontrolled introduction of fresh air into a building.
1. Most subjective of all losses
2. Oftentimes the largest of all heat losses.
Sometimes comprises up to 30% of the total
heating load.
3. Ends up being an “educated guess”

15. Infiltration
The uncontrolled introduction of fresh air into a building.
1. Most subjective of all losses
2. Oftentimes the largest of all heat losses.
Sometimes comprises up to 30% of the total
heating load.
3. Ends up being an “educated guess”
I. Infiltration
A. The uncontrolled introduction of fresh air into a building.
1. Most subjective of all losses
2. Oftentimes the largest of all heat losses.
Sometimes comprises up to 30% of the total
heating load.
3. Ends up being an “educated guess”

16. Why Is This Important? All buildings leak
A tight building will leak .5 AC/H
A leaky building can leak 3 AC/H
Regardless of climate, air leaking into walls causes problems

17. Ventilation The mechanical introduction of outside air (OA) to:
Replace Oxygen
Dilute contaminants
Pressurize the building

18. Moisture Load

19. Infiltration Calculation Methods
Crack method
Air Change Method
‘Averaging’ method (‘I don’t know so I’m going to throw a dart’ method)

20. Crack Method
Presumes that an accurate estimate can be obtained by estimating the rate of infiltration per foot of crack for doors and windows
CFM = Ft. of Crack x Infiltration Rate
QS = 1.1 x CFM x (T2 – T1) in BTU/HR
I. Crack Method
A. Presumes that an accurate estimate can be obtained by
estimating the rate of infiltration per foot of crack.
1. For doors, you must also add the volume of
air that “infiltrates” when the door is in use.
B. The CFM is then defined as
CFM = Ft. of Crack x Infiltration Rate.
C. Use Table 3.4 of your text.

21. Add Infiltration Through Open Door
Determine Door Usage
ת = Number of People per Minute
Determine CFM per person (D)
CFM = ת x D
I. Add Infiltration Through Open Door
A. Determine Door Usage
1. Owner or Architect will be the best source
for ת, the number of people per minute
B. Determine the CFM per Person (D)
1. From Table 3.5
CFM = ת x D
LEED-NC Credit EQ 5 for providing vestibules.

22. Infiltration by Crack Method
Add CFM from Crack losses to CFM for Open Door losses

23. Mitigate These Losses How do you reduce or mitigate these losses?
(Review)
Really good weather-stripping
Pressurization
Vestibules
Revolving doors
Seal cracks and openings
CO2 sensors
DOAS systems

24. Mitigation Strategies
Pressurization
QS = 1.1 x CFM x (T2 – T1)
Vs.
QS = 1.1 x (CFH/ft of crack x ft of crack)/60 x ΔT
You own the variables!

25. Infiltration Variables
Review
Wind velocity and direction
Stack effects
Corner rooms
Exhaust fans on or off
Pressure zoning
Frequency of use
Maintenance
I. Infiltration Variables
A. Wind velocity and direction
B. Stack effects
C. Corner Rooms
1. Remember, the wind blows on one side at a
time!
A. Use either the greater of the
two CFM values or 70% of the
total.
D. Exhaust fan operation
E. Pressure zoning
F. Frequency of use
G. Maintenance

26. Stack Effect
Review

27. CFM = Volume (ft3)/Frequency (minutes)
Air Change Method
Often used in residential construction and in large warehouses and similar buildings
CFM = A.C.H. x Volume (ft3)/60 or
CFM = Volume (ft3)/Frequency (minutes)
I. Air Change Method
A. Oftentimes used in residential construction and in large
buildings like warehouses and other similar commercial
structures.
CFM = A.C. H. x Volume (ft3)/60 or
CFM = Volume (ft3)/Frequency (minutes)
B. Can also be determined by Code
1. For example, the UBC requires you to use
not less than .5 CFM/square foot

28. Air Change Method Uses same formula for sensible
Equals one room change
Designer will use 0.3 to 2.0 air changes per hour (ACH)
Occupancy
Climatic condition (i.e. winter vs. summer)
Construction (tight or loose)
Least accurate of the three methods
Qsens = 1.1 x CFM x T

29. Table 2-8

30. Heat Loss Due to Infiltration
Btu H = (.018) x (ACH) x V x (Ti – To)
ACH = air exchanges per hour
V = volume
Ti = inside temperature
To = outside temperature

31. Heat Loss Due to InfiltrationOR

32. Heat Loss Due to Infiltration
Btu H = 1.1 x CFM x (Ti – To)
CFM = (ACH x volume) / 60 min per hour

33. Heat Loss Due to Infiltration
Please Note:
For tight construction use 0.5 for ACH.
For medium construction use .85 for ACH.
For loose construction use 1.3 for ACH.
For really bad construction use 2.0 for ACH
For the summer months (cooling) use 70% of the winter values.

34. Infiltration & Ventilation
Btu Hour Loss due to Infiltration Main Area
CFM
Ht. W. L.
1.10
air exch.
vol. In cf
/ 60
Temp. Ch. 12
46.66
74.66
0.5
41,803.63
348.36 76
29,123.19
Btu Hour Loss due to Ventilation Main Area sf
cfm exchange
Occup.
3,483.64
0.180
34.84
66,983.35 Ra Rp
Occup/1000
0.18 5
10.00

35. Heat Gains Due to Infiltration
Latent Load
BtuH = 4500 x (air exchanges x (volume) /60) x
(W Final – W Initial)
(W Final – W Initial) = Difference Ratio Pounds of Moisture per dry air

36. Heat Loss Due to Ventilation
Btu H = 1.1 x [(Ra x square feet of building )
(number of people in the building x Rp )] x
(Ti – To)

37. Heat Loss Due to Ventilation

38. Heat Loss Due to Ventilation
Ra = Area Outdoor Air Rate
Rp = People Outdoor Air Rate
Example: Pharmacy
Ra = .18
Rp = 5

39. Heat Loss Due to Ventilation
Btu H = 1.1 x [ (.18 x 3,632) + (30 x 5)] x 76o
= 67,214

40. Ventilation
and / or
Infiltration