heating losses infiltration and ventilation n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Heating Losses- Infiltration and Ventilation PowerPoint Presentation
Download Presentation
Heating Losses- Infiltration and Ventilation

Loading in 2 Seconds...

play fullscreen
1 / 41

Heating Losses- Infiltration and Ventilation - PowerPoint PPT Presentation


  • 116 Views
  • Uploaded on

Heating Losses- Infiltration and Ventilation. ARCH-432. 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. Attendance.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Heating Losses- Infiltration and Ventilation' - mort


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
attendance
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
attendance1
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.

attendance2
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

slide6

Greetings

Capt. Kirk

Aeschylus

attendance3
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.

big picture moment

roof

Infiltration and Ventilation

Glass

conduction

Exterior

wall

Floor

Big Picture Moment

Ceiling

Partition

slide9

roof

Infiltration and Ventilation

Glass

conduction

Exterior

wall

Floor

Five main types of heat loss

1. Transmission (conduction)

2. Infiltration (convection)

3. Ventilation (convection)

4. Radiation (radiation)

5. Moisture migration

Ceiling

summary of heat losses
Summary of Heat Losses
  • Wall
  • Roof
  • Floor
  • Windows
  • Doors
  • Infiltration
  • Ventilation

Envelope Losses

what you need to know
What You Need To Know
  • The difference between ventilation and infiltration
  • Calculation methods for both ventilation and infiltration
what you need to be able to do
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
terms
Terms
  • Infiltration
  • Exfiltration
  • Ventilation
  • Direct Outside Air System (DOAS)
infiltration
Infiltration

“The uncontrolled introduction of outside air into a building.”

infiltration1
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”

why is this important
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
ventilation
Ventilation
  • The mechanical introduction of outside air (OA) to:
    • Replace Oxygen
    • Dilute contaminants
    • Pressurize the building
infiltration calculation methods
Infiltration Calculation Methods
  • Crack method
  • Air Change Method
  • ‘Averaging’ method (‘I don’t know so I’m going to throw a dart’ method)
crack method
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

add infiltration through open door
Add Infiltration Through Open Door
  • Determine Door Usage
    • ת = Number of People per Minute
  • Determine CFM per person (D)

CFM = ת x D

LEED-NC Credit EQ 5 for providing vestibules.

infiltration by crack method
Infiltration by Crack Method
  • Add CFM from Crack losses to CFM for Open Door losses
mitigate these losses
Mitigate These Losses
  • How do you reduce or mitigate these losses?

(Review)

mitigation strategies
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!

infiltration variables
Infiltration Variables

Review

  • Wind velocity and direction
  • Stack effects
  • Corner rooms
  • Exhaust fans on or off
  • Pressure zoning
  • Frequency of use
  • Maintenance
air change method
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)

air change method1

Qsens =1.1 x CFM x T

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
heat loss due to infiltration
Heat Loss Due to Infiltration

Infiltration

Btu H = (.018) x (ACH) x V x (Ti – To)

ACH = air exchanges per hour

V = volume

Ti = inside temperature

To = outside temperature

heat loss due to infiltration2
Heat Loss Due to Infiltration

Infiltration

Btu H = 1.1 x CFM x (Ti – To)

CFM = (ACH x volume) / 60 min per hour

heat loss due to infiltration3
Heat Loss Due to Infiltration

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.

heat gains due to infiltration
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

heat loss due to ventilation
Heat Loss Due to Ventilation

Ventilation

Btu H = 1.1 x [(Ra x square feet of building ) +

(number of people in the building x Rp )]

x

(Ti – To)

heat loss due to ventilation2
Heat Loss Due to Ventilation

Ventilation

Ra = Area Outdoor Air Rate

Rp = People Outdoor Air Rate

Example: Pharmacy

Ra = .18

Rp = 5

heat loss due to ventilation3
Heat Loss Due to Ventilation

Ventilation

Btu H = 1.1 x [ (.18 x 3,632) + (30 x 5)] x 76o

= 67,214

slide40

Ventilation

and / or

Infiltration