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