![Page 1: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/1.jpg)
Room Air DistributionPresented by Randy Zimmerman
![Page 2: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/2.jpg)
Introduction
TC 5.03 update Mixed air systems vs. stratified systems Thermal comfort Ventilation effectiveness Diffuser performance Overhead heating Product selection Questions and answers
2
![Page 3: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/3.jpg)
TC 5.03 Room Air Distribution
TC 5.03 Officers– Jerry Sipes – Chair– Randy Zimmerman – Vice Chair/Research Chair– Kevin Gebke – Secretary– Fred Lorch - Membership– Curtis Peters – Handbook– Andrey Livchak - Programs
3
![Page 4: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/4.jpg)
TC 5.03 Room Air Distribution
TC 5.03 Activities– RP-1546 – ADPI Update (due 2014)– RP-1629 – Energy Performance of Active Beam
Systems (just started)– SPC 200 – MOT Active Chilled Beams (public
review)– SPC 130 – MOT Terminal Units (public review)– SPC 70 – MOT Air Inlets and Outlets (just formed)
4
![Page 5: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/5.jpg)
TC 5.03 Room Air Distribution
Join TC 5.03 – a large and active committee– Chapters in (3) ASHRAE Handbooks
• Fundamentals• Applications• Systems and Equipment
– Subcommittees• Room Fan Coils• Chilled Beams• Underfloor Air Distribution• Air Curtains
5
![Page 6: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/6.jpg)
So Many Choices
There’s a Good, Better and Best System for Every Building Old and New Technology
– Overhead Air Distribution– Underfloor Air Distribution– Active Chilled Beams– Displacement Ventilation
![Page 7: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/7.jpg)
GRD’s
Grille– Outlet similar in size to duct size
Register– Grille with an integral dampering device
Diffuser– Outlet that is often larger than duct size– Designed to create an air pattern
They are all outlets!
![Page 8: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/8.jpg)
The Occupied Zone
Occupied Zone– 6.0 ft above floor– 3.3 ft from outside wall– 1.0 ft from interior wall
3.3’
6.0’ 1.0’
![Page 9: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/9.jpg)
Conventional Mixed-Air System
![Page 10: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/10.jpg)
Fully-Stratified System
![Page 11: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/11.jpg)
Supply air 38-55oF Cold air supplied outside the
occupied zone, thoroughly mixes with room air
Creates an air pattern on the ceiling and/or walls
Picks up heat and pollutants at the ceiling level
Creates low velocity room air motion
Ideally creates uniform temperature throughout the space and minimizes stratification
Mixed-Air System Concepts
![Page 12: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/12.jpg)
Supply air 63 - 68oF Cool air supply displaces
warm room air at low velocities
Uses the natural buoyancy of warm air to provide improved ventilation and comfort
Cold air moves slowly across the floor until it reaches a heat source, then rises
Improved IAQ
Fully-Stratified Concepts
![Page 13: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/13.jpg)
Improved Contaminant Removal
Stratification creates a single pass Unlike mixed-air, contaminants are not redistributed
throughout the room
Displacement Ventilation Overhead System
![Page 14: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/14.jpg)
ASHRAE Standard 62.1 - Ventilation for Acceptable Indoor Air Quality
Zone Air Distribution Effectiveness, Ez
Best Overhead System (Ez = 1.0) Displacement Ventilation (Ez = 1.2)
– UFAD also qualifies if T50 is 4.5 ft or less– 16.7% Less Fresh Air Required
Improved Ventilation
![Page 15: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/15.jpg)
Thermal Comfort
ASHRAE Standard 55 – Thermal Environmental Conditions for Human Occupancy
Maximum recommended ∆Thf = 5.4°F
![Page 16: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/16.jpg)
What About Heating?
Fully-stratified systems typically use a secondary system for heating– Low velocity warm air would short
circuit to the ceiling– Fin tube perimeter heat is often
used
![Page 17: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/17.jpg)
Dual Plenum Diffusers
Dual plenum diffusers provide– Displacement outlet for cooling– Grille for low sidewall heating– Internal diverting damper– Allows a single system to cool
and heat in mild climates
![Page 18: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/18.jpg)
Outlet Performance
Tested per ASHRAE 70– SP and TP– Area factor, Ak
– Sound level– Throw, drop and spread
![Page 19: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/19.jpg)
Outlet Performance
Pressure drop (in wg)– SP measured– TP = SP + VP
Area factor, Ak (ft2)– cfm = Ak x fpm
Sound level (dB ref 10-12 w)– NC assumes 10 dB room
effect
![Page 20: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/20.jpg)
Outlet Performance
Throw– Terminal velocities– T150, T100, T50
– Measured from centerline– Isothermal (unless specified)
Drop– Distance below ceiling to center of
discharge jet Spread
– Unbounded jets spread at 11°angle (on each side)
![Page 21: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/21.jpg)
Area Factor vs. Free Area
Free area does not govern outlet performance Performance is related to geometry
– Hole size/shape/number– Material depth– Curved/angled surfaces
Free area may or may not be easy to determine, but it’s not really useful information
![Page 22: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/22.jpg)
ADPI
Air Diffusion Performance Index (ADPI)– Statistically relates local temperatures and
velocities to occupant comfort– Ratio of diffuser T50 to characteristic length of the
room being served– ADPI > 80 is acceptable– Currently only applies to cooling applications– Soon may be expanded to include more diffuser
types and add heating applications
![Page 23: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/23.jpg)
ADPI
ASHRAE RP-1546– Conducted at University of Texas at Austin– Verify original research– Expand the types of outlets– Run heating tests– Testing will be completed by August, 2014
![Page 24: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/24.jpg)
ADPI Example
ADPI Example – 200 cfm – 20° ∆T– 400 ft2
Results for 24x24 diffusers with 8” necks– Plaque Face = 93.0– Multi-Cone = 93.0– Perforated = 84.8
It often makes sense to look at typical rather than 100% design conditions…
![Page 25: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/25.jpg)
Overhead Heating
Discharge temperature affects minimum ventilation – In overhead heating applications, discharge temperatures
should never be more than 15°F higher than the desired room temperature and T150 must be within 4.5 ft from the floor (Ez = 1.0)
– If ΔT > 15°F, then Ez = 0.8 and cfm increases by 25%
![Page 26: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/26.jpg)
Split Pattern Linear
50/50 throw pattern is the best compromise for both heating and cooling
Works best when splitting the diffuser length, rather than splitting slots
![Page 27: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/27.jpg)
Air Patterns
Cross flow– Ceiling– Longer throw
![Page 28: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/28.jpg)
Air Patterns
Round– Ceiling– Shorter throw
![Page 29: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/29.jpg)
Air Patterns
Swirl (floor) Displacement (sidewall) Linear (ceiling) Linear (air curtain) Laminar (OR, clean rooms) Hemispherical (lab,
industrial)
![Page 30: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/30.jpg)
Return Grilles
Contrary to popular belief – return grille locations generally do not affect room air motion
Return grilles merely provide an exit
![Page 31: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/31.jpg)
Surface Effects
Discharge jets attach themselves to surfaces– Ceilings– Walls– Glass
Obstructions with an angle of incidence greater than 15° can kick the air pattern off the ceiling
![Page 32: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/32.jpg)
Open Ceilings
Unless otherwise specified assume – Ceiling diffusers were tested with a ceiling– Side wall grilles were tested near a ceiling
Internal vs. external Coanda pocket Most diffusers need a ceiling for horizontal air
pattern Sometimes a small lip can be added to create
a ceiling effect Free jets result in a 30% throw reduction due
to increased expansion
![Page 33: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/33.jpg)
Temperature Effects
T150 is temperature independent – velocity driven
Horizontal ceiling throw– Cooling decreases throw by 1% per °F– Heating inceases throw by 1% per °F
Example – Catalog (isothermal) 4-7-9– Cooling 4-6-7– Heating 4-8-11
![Page 34: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/34.jpg)
Active Length
Linear diffusers should not have active sections longer than 10 ft
Overly long active sections cause problems– Extended and unpredictable throw– Undulating air patterns
Solutions– Provide 1-2 ft inactive breaks between sections– Alternate throw direction
![Page 35: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/35.jpg)
Acoustics
Select diffusers such that they will not be heard
Noisy diffusers create a poor communication NC set by in octave bands 4-6 (500, 1000,
2000 Hz) – speech interference bands 10 NC points lower than desired room level,
and rarely higher than NC25 unless it’s an industrial application
![Page 36: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/36.jpg)
What Type To Select?
The choice can depend on many things– Air pattern – Performance – Appearance– Cost– Space limitations– Installation/ceiling type
![Page 37: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/37.jpg)
Summary
Many types of systems and outlets are available, but there’s always a best choice
Selecting the right air pattern is critical Be aware of surfaces and ceilings Keep overhead heating temperatures low Select diffusers to be inaudible
![Page 38: Room Air Distribution Presented by Randy Zimmerman](https://reader036.vdocument.in/reader036/viewer/2022062511/551b1a4e55034607418b5786/html5/thumbnails/38.jpg)
Questions and Answers
Questions?
Thank-you!