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 — 2×10’s at ceiling, supporting a single 2×10 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.
