Weatherization: Low-Cost, High-Return Energy Upgrades

West Union, IA

Jan 11 2009 By | 0 comments

General Specs

Location: West Union, IA

Weatherization contractor: Jim Perry, Northeast Iowa Community Action Corporation

Area affected: 2,500 sq. ft.

General Principles

  • “Best practices” from leading weatherization programs
  • Lead-safe weatherization work
  • Building Envelope Measures

  • Blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. showed air leakage was reduced from 4,800 cfm (0.97 air exchange per hour) to 3,546 cfm (0.61 air exchange per hour)
  • Testing included whole-house and room-to-room pressurization tests
  • Infrared imaging (before and after)
  • Weatherstripping of doors and windows
  • Complete thermal bypass inspection; all problems addressed
  • Spray foam used for air sealing of attic floor and crawl space rim joist
  • Polyethylene sheet installed on crawl space floor
  • Blown-in cellulose attic insulation (approaching R-40 where space allowed)
  • HVAC Measures

  • Duct-tightness test (before and after)
  • Furnace tested for efficiency and combustion safety
  • Carbon monoxide and smoke alarm tests
  • Plumbing Measures

  • Insulation jacket installed on water heater
  • Hot water pipes insulated
  • Lighting Measures

  • Incandescents swapped for CFLs
  • Homeowner Education

  • Clients educated about moisture issues, lead safety, and other issues pertinent to their situation
  • Integrated solutions address energy, health, and safety in this state-funded assistance program

    Each year, Northeast Iowa Community Action Corporation (NEICAC) uses state funding to weatherize about 100 homes. On this 100-year-old two-story home, and others like it, weatherization crews have performed a variety of diagnostic tests and implemented low-cost, high-return strategies for improving overall energy efficiency — without extensive modifications.

    This 2,500-square-foot home is typical for the area but larger than many of the houses in NEICAC's program. The work done on this house reduced air leakage by almost 50%.

    Design approach: integrated solutions
    All weatherization projects aim to improve a home's energy efficiency. The best weatherization programs take a whole-house systems approach, integrating energy efficiency improvements with measures designed to address combustion safety, moisture management, ventilation, and overall building durability. The basic process is tailored to the unique challenges of each house as revealed by diagnostic tests.

    Fortunately, this home didn't have any complex needs, but Jim Perry says that it's always best to be careful. For example, large atmospherically vented furnaces connected to oversized brick chimneys contribute to high air exchange rates. Although these high infiltration rates exact an energy penalty, they help keep the house dry. "In an old, damp home with an old furnace, if you take that furnace out and put in a high-efficiency condensing furnace, now the furnace is not helping dry the place out," said Perry. "You have a bigger problem than you had to begin with.”

    Evaluate conditions, educate homeowners, and execute a plan
    Jim’s weatherization team includes two two-man crews, a coordinator, and an evaluator. First, they evaluate the home. This includes photos, preliminary diagnostic tests, inspecting for moisture and health issues, and checking combustion equipment and appliances for efficiency and carbon monoxide emissions. At this stage, they talk with the homeowner, give them a lead safety booklet, and explain how they approach lead-safe weatherization.

    Once the homeowners give permission to make improvements, the crew begins. Most air sealing work is performed in the attic and basement, where it will have the biggest effect. The crew also adds weatherstripping and insulation, and replaces incandescent bulbs with CFLs.

    When necessary, they replace energy-wasting refrigerators and freezers. The appliances at this house, however, weren't bad enough to warrant switching. A weatherization project, including final inspection and testing, can take anywhere from three to six months to complete; this house took four.

    How to do a lot with a little
    Because state financing is limited, weatherization projects incorporate only the lowest-cost, highest-return measures; despite the wishes of many clients, these measures do not typically include new windows or doors. Ultimately, basic weatherization strategies are able to reduce energy costs and extend fuel assistance dollars for a larger group of people than large-scale energy retrofits might.

    Lessons Learned

    Every house has unique challenges
    For this home, one of the trickiest spots was an open porch with a roof above it. The wall and floor cavities of the adjacent conditioned spaces of the home have nothing but board sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. between them and the enclosed porch ceiling. Because the crew realizes that this is a common situation in many homes of this era, these thermal flaws are spotted quickly. The required solution — opening up the porch ceiling so that workers could climb in — was a bit more invasive than most weatherization procedures, but that was the only way to get at these gaps to seal them.

    Sometimes weatherization isn't the answer
    A successful weatherization project requires a look at the whole house. NEICAC has a set of project guidelines to help crews cover all the bases. For example, if a home's blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. shows less than 0.35 air exchange per hour, Jim's crew must install a mechanical ventilation system. This house didn't require one; but if a house does, the team checks for an existing exhaust fan or adds a low-decibel, high-efficiency fan to the bathroom, often with a dehumidistat or a timer programmed to stop after 20 or 30 minutes.

    If a home has significant structural, moisture, or mold problems, the team tries to address these first, bringing in additional expertise if necessary. If a problem is extensive, however, simple weatherization may not be the answer. Weatherization contractors must rely on a thorough evaluation and strong intuition when deciding whether it's time to jump in and get to work or to admit that the best solution is outside the scope of their responsibilities.

    Further Resources

    The U.S. Department of Energy has a list of state weatherization contacts on its weatherization home page.


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    Image Credits:

    1. Northeast Iowa Community Action Corporation
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