ME, ECE, BE Capstone Design Programs

To Predict To Design To Perform

R806: Unvented Roof Assembly John Bryan, Cameron Burchak, Justin David, Joseph Henderson, David Miller

Sponsors: Mr. Bobby Byrd of RoyOMartin Advisors: Dr. Charalampopoulos, Mr. GillioP.E.

Project Objectives1) Design a cost effective hybrid unvented roof assembly

• efficiently utilizes an under decking radiant barrier• Uses under-sheathing open cell spray foam

2) Address the moisture that gets trapped in the attic.Testing

Test 2 identical 8’X8’ scale model Unvented homesPhase I Phase II

Correctly sized vs oversized Correctly sized vs Enthalpy Wheel

Testing apparatus•Humidistat, Thermocouples, Moisture Meter, Watt meter

BackgroundR806 is the residential code on how to properly build and insulate theroof deck of a home

Reflective Insulation

This is a model of baffle system that has a reflective material attached to it in order create a reflective air gap with an R-value of 9.5.

Engineering Specifications• Constraints of R806.5• Roof deck R-value of at least 38 • Less than 16% moisture content in wood• Utilizes Open Cell Spray Foam and Reflective Insulation

Moisture Extraction method for Retrofit Homes New Construction Houses• Designing for new construction the moisture issue can be addressed

by proper sizing of the HVAC equipment using a tedious method called Manual J.

Timeline and BudgetSafety

House ConditionsSpace Attic

RH (%) 50 35

Temp (⁰F) 75 ± 5-10

Design ConditionsCity : Baton Rouge, Louisiana

Summer Winter

92⁰F db 77⁰F wb 30⁰F db

1. The desiccant wheel absorbs moisture from the attic airstream.

2. This moisture is released from the wheel into the return air stream

3. Moisture condenses at the evaporator coil.

Mechanical Electrical Bio/Chemical

Hazard • Motors• Fans

• Shock• Fire

• VOCs• Wood Rot

EngineeringControl

• SafetyGuards

• Wire Coating• Secure Connections• Sealed electrical

boxes

• Control Infiltration• Moisture Removal

BehavioralControl

• WarningSigns

• Warning signs• Smoke detectors N/A

Vented• Typically common design• Does not include attic in

thermal space• Attic can reach temperatures

of 130⁰F• Great Temp difference

between attic and space• Moisture is vented out of attic

Unvented• Put into Practice in 2006• Includes Attic in Thermal

space• Attic is only 5-10⁰F warmer

than set point of space• Duct work is in semi-

conditioned space• Moisture gets trapped in attic

http://www.buildingscience.com/documents/insights/bsi-074-duct-dynasty

Results

40

60

80

100

120

140

160

180

7 9 11 13 15 17 19 21 23

Tem

pera

ture

(F)

Time (hrs)

Roof Deck Temp Distribution Roof DeckAir SpaceInsulationAttic TempOutside Temp

4/2/15

Peak ValuesSensor Location ff F

Outside Temp 87.8Roof Deck 123.8Air Space 161.6Insulation 82.4Attic Space 75.2Time: 1:30 PM

Building Material, 32%

Misc, 16%Spray Foam, 10%

Air Conditioner, 10%

Remainder, 24%

Budget$10,000

Electrical

Testing Apparatas

Category Amount

Building Material

$ 3,241.14

Misc. $ 1,615.15

Electrical $ 250.81

Testing Apparatus

$ 553.07

Spray Foam $ 1,000.00

Air Conditioner $ 977.51

Remainder $ 2,362

TOTAL $ 7,637

1/3/

15

1/30

/15

2/30

/15

3/21

/15

4/15

/15

4/22

/15

40

45

50

55

60

65

70

75

80

0 100 200 300 400 500 600 700 800 900 1000

Hum

idity

[%]

Time [min]

Proper Sized System Humidity

Attic

Space

40

45

50

55

60

65

70

75

80

0 50 100 150 200 250 300

Hum

idity

[%]

Time [min]

Desiccant Wheel System

Attic

Space