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Energy Efficiency Review of Habitat for Humanity House

I'm working on a Habitat for Humanity house in Austin, TX, starting on January 16, 2010, and continuing for the next 10 to 11 weeks. During this period, I'll be reviewing the energy efficiency of the major components of the home, including the framing, windows and doors, roofing, attic ventilation, insulation and sealing, and air conditioning and heating system. I'll be looking at all the energy efficient aspects of the house and any potential areas for improvement. I hope you enjoy this blog. I'd enjoy hearing your questions or comments throughout this process!

Energy Efficient Stud Wall Construction

One of the fundamental energy efficient and green building components of a home is the quality of wall construction. The walls in this Habitat house are built on 24" centers (24" spacing between each wood stud). Walls built on 24" centers use 25% less wood, and are approximately 7% more energy efficient than walls of the same thickness built on 16" centers. This is because wood conducts heat almost 3 times faster than the comparable thickness of fiberglass insulation. The goal of energy efficient framing and green building is to minimize the amount of wood framing in the house. Wood studs should only be used as needed for structural integrity. Reduction of wood benefits both the environment (fewer trees cut down) and the homeowner (lower utility bills due to reduced heat loss in the winter and heat gain in the summer through the walls and ceiling).

Sill seal (3 1/2" wide strip of pink plastic foam) is applied to the bottom side of the sill plate on all stud walls. The purpose of sill seal is to stop air infiltration, water and bugs from entering the house. Unfortunately, sill seal isn't always 100% effective because concrete slabs aren't always level, and sill seal can't always compensate for this. Also, sill seal can't provide an effective seal between two adjoining sill plates, as seen in this picture. Caulking the joint between the slab and sill plate with silicone caulk is recommended. This will provide an additional seal against air leaks, water, and bugs.

Notice that multiple 2x4's are used adjacent to each other in this section of wall. Depending on structural requirements, it would be more energy efficient to remove some of these studs and replace them with insulation for the same reasons previously discussed - insulation transmits heat at a much slower rate than wood.



Lastly, this is an infra-red image of the inside of a finished home where the exterior wall has improperly sealed sill plates. Notice the cool air (dark blue) entering the house at the bottom of the wall between the base board and flooring. The base boards aren't caulked to the flooring, so cool air enters the house under the base boards. The source of cold air could also be coming from the wall assembly or attic with the same results. To remedy this situation in a finished home, caulk the joint between the flooring and base board.

Cash for Caulkers

I wanted to update everyone on an exciting program that's being proposed. The government is proposing a subsidy for home efficiency upgrades called Home Star, but is being nicknamed 'Cash for Caulkers'. With some stipulations, homeowners can get half of their efficiency upgrades rebated up to $12,000. What does this mean for you if you're in Austin? Well, when you combine that with rebates from Austin Energy, you could be looking at quite a rebate.
Right now, Cash for Caulkers is still at the drawing board stage, but we'll be sure to keep you updated on any changes or news right here.

1st Choice Energy in the News

Hello out there! Welcome to the 1st Choice Energy blog. We're an energy audit and home improvement company in the city of Austin, Texas. We also offer service to Round Rock, Georgetown, Pflugerville, and surrounding areas. I'll be posting up some helpful tips for reducing energy and some useful articles as well.

Here's a piece that KXAN did on 1st Choice Energy back over the summer. Enjoy!