utsa-design strategies for comfort
Post on 07-Aug-2015
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Quality Passion Knowledge
Design Strategies for Comfort
Building Technology IV University of Texas, San Antonio
IBS Advisors
Consulting Education MediaProvider
Brett Dillon• Managing Director, IBS
Advisors, LLC
• Member, RESNET Board of Directors
• Chair, RESNET Technical Committee
• Member, RESNET Training & Education Committee
• USGBC LEED for Homes Green Rater Faculty™
• RESNET-accredited Trainer
• RESNET-accredited Quality Assurance Designee
• 4th Generation Builder
• Author of books on:
• HVAC
• Weatherization
• Advanced building techniques
• HERS Ratings
5 Comfort Factors
Structure
Systems
Commissioning
Surrounding Air
Temperature68º F, heating 78º F, cooling
Moisture Levels in Air
30%-50% RH < 80º F Dewpoint
Velocity of Airflow
> 25 fpm < 50 fpm
Evaporative Rate
Related to Moisture Related to Air Velocity
Clothing Levels
Related to Culture & Lifestyle
Temperature Control
Shelter from sun Maintain warmth
Garage Living
Space
Living Space
Living Space
Temperature Controls
Shade
Temperature ControlsSolar
RadiationAbsorptance
Transmittance
Albedo
Temperature Controls
Uave = (U1 x A1) + (U2 x A2) / Atot Q = U x A x ΔT
Temperature Controls
Siding, 1.5
WRB, 58
OSB,
Insulation, varies
Primed & Painted Drywall,
2
Building Material ~ Perm RatingFiber cement siding 1.5
OSB 0.75Primed & Painted Gypsum Board 2
Tyvek® Housewrap 58Cellulose 75Fiberglass 120
Open cell spray foam 10Closed cell spray foam 0.86
Airflow Velocity
Hole Pressure Difference
Stack Effect
Mechanical Systems
• Kitchen Range Hood
• Bath Exhaust
• Clothes Dryer
• Ducted HVAC
Evaporative Rate
Clothing Levels
SystemsSystem Concept
Load Calculation
Equipment Selection
Air Distribution
Duct Size Calculation
Adjust, Test & Balance
Manual RS
Manual J
Manual T
Manual S
Manual D
Heating CoolingT-stat setpoint 70°F 75°F
RH 25% 40%Temp @ T-stat 68°F - 72°F 72°F - 78°F
Room-Room or Level-Level ∆ T + 4°F + 6°F
Temp in any room + 2°F of set point + 3°F of set point
Floor temp over slab or unconditioned space > 65°F, 4” above floor
Filtration > MERV 8 > MERV 8
Ventilation 7.5 cfm/person + 1 cfm/100 ft2
7.5 cfm/person + 1 cfm/100 ft2
Duct Leakage < 6% < 6%
Spread
Manual T
Sensible Heat Ratio
Supply Air Room Air Temperature
Difference
< 80% 54 75 2180% to 85% 56 75 19
> 85% 58 75 17
Manual S
Manual D• Required under IRC M1601.1
• Implies room-by-room load calculation must be performed
• CFM
• SHR
• ΔT supply-return
• Sensible load
• Friction rate
• Pressure drop x 100 / total effective length
Supply Duct Sizing
• What temperature does the air need to be to meet the load?
• How many CFM of air must be delivered to meet the load?
• Sensible Load / (1.1 x ΔT)
Duct Layout
Trunk and Branch SpiderRadial
Courtesy of Building America Industrialized Housing Partnership, FSEC & Dennis Stroer
Commissioning
AAAS.org
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