PATH - A Public Private Partnership for Advancing Housing Technology

Brownsville, Texas

Demonstration Site: Cameron Park Colonia

Final Case Study Report [.pdf, 828 KB] August 2005

The Community Development Corporation of Brownsville, Texas (CDCB) builds between 25 and 40 small homes in local "colonia" settlements of new immigrants each year. Often replacing shacks with no indoor plumbing, these livable, highly cost-effective three-bedroom homes are built on land owned by the homeowners who qualify for the low-interest loans.

Technologies

ENERGY STAR ^® RATING

• [IMAGE: Construction in progress.] Environmental Protection Agency (EPA) sponsors the program
• Home must be designed and tested to exceed the Model Energy Code by 30% or more
• Home is tested for leakage using a "blower door"
• Ducts are tested for leakage using a "duct-blaster"

LOW-E DOUBLE GLAZING

• Now required by Texas code
• Used in housing nationwide
• Very effective in reducing cooling load

HIGHER LEVELS OF ENVELOPE INSULATION

• Small but noticeable effect
• R-13 in walls, R-30 in attic

HIGHER LEVELS OF DUCT INSULATION

• Small but noticeable effect
• R-6.5, 1--1/2" ductboard

MASTIC SEALING AT JOINTS IN DUCTWORK

• More effective than tape
• Last the life of the home

HIGHER EFFICIENCY AIR CONDITIONING UNIT

• Seasonal Energy Efficiency Rating (SEER) of 12 instead of 10
• Now required by Texas code

"MANUAL J" DESIGN

• "Right-Sized" equipment: 1-1/2 tons of cooling
• Very important not to oversize air conditioning (oversizing creates mold)
• Manual J is a simple-to-use design tool, available for hand calculation or in user-

ENERGY STAR ^® REFRIGERATOR

• More efficient
• Savings of $35/year or more pay for small extra cost in a short time

FLUORESCENT LIGHTING

• Saves 60% of the cost of lighting
• New fluorescent lamps don't hum or flicker, and they have excellent color

INTAKE-ONLY VENTILATION

• Small, well-insulated homes need mechanical ventilation
• Exhaust ventilation is not desirable in hot humid climates
• Sucks hot, humid air into contact with cool walls and ceilings
• Creates condensation and mold
• Intake-only ventilation is provided by 6" duct from outside to air conditioning fan
• When air conditioning fan runs, it pulls ventilation air in, filters it and cools it

DUAL-PITCH ROOF

• 5 in 12 pitch on the long sides
• 6-3/4 in 12 pitch on the short sides (30o maximum slope)
• Raises the apparent height of the roof from the front
• Provides a 12 foot main ridge -- center 40% of the home is framed like a gable roof
• Old design: 3 full-length rafters
• New design: 7 full-length rafters

SIMPLIFIED RIDGE SUPPORTS

• Hip ridges carry a large load
• Clear span would require two 11-7/8" Microlams 18 feet long
• Revised design uses 2 -- 2x10's at ceiling, supporting a single 2x10 ridge at its center

REDUCED NUMBER OF INTERIOR STUDS

• 24" on-center spacing saves studs without compromising quality
• Used in housing nationwide
• Single stud at door jambs (to be done in future homes)

LADDER BRACING AT TEE INTERSECTIONS

Normal framing:

• Uses two extra studs
• Creates uninsulated space outside of stud
• Ladder uses three scraps 16" long, saves 1-1/2 stud length
• Ladder allows insulator to continue insulation outside of Tee wall

USES "PEX" TUBING

• NOT anything like the polybutylene tubing that failed 25 years ago
• PEX= Cross-linked Polyethylene
• Highly proven system, being used nationwide
• Extremely durable, cannot kink
• VERY desirable in Brownsville, which has highly corrosive water -- water will not attack PEX
• Effective crimped fitting system for making joints

MANIFOLD DISTRIBUTES WATER STRAIGHT TO FIXTURE

• This system is unique because it has a plastic manifold -- no corrosion problems
• 14 ports -- 7 for hot water and 7 for cold -- tubing is color-coded
• PEX tubing runs straight from manifold to fixture
• Manifold has shut-off valves for every fixture in a central place
• There are NO hidden joints or fittings -- every line has a joint at each end only
• 3/8" lines cut down on the wait for hot water at remote fixtures

RELIABLE VENTS REDUCE THE AMOUNT OF VENT PIPING

• Plumbing waste piping needs venting to work properly
• Venting usually works through a pipe going through the roof that lets air in AND sewer gases out
• This device works within the house, by letting air in but blocking the escape of sewer gases
• The result: reduced vent piping (only one vent needs to go through the roof)

About of half these homes were planned to be framed by on-the-job trainees in the YouthBuild program, and these homes are an obvious target for experiments in lumber savings that take less time and thought to erect.

Status Updates:

This project has been completed.

Project Chronology

Content updated on 7/17/2006

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