utsa-design strategies for comfort
TRANSCRIPT
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