Holistic Medicine for Existing Homes

Before beginning a remodeling project, contractors routinely consider its impact on the design and construction of the rest of the home - but not everyone considers the impact on whole-house performance. This can have ill effects on the home and/or occ...

July 31, 2003


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Before beginning a remodeling project, contractors routinely consider its impact on the design and construction of the rest of the home - but not everyone considers the impact on whole-house performance. This can have ill effects on the home and/or occupants.

What is home performance? In simple terms, home performance addresses five basic attributes: safety, health, durability, comfort and efficiency. These attributes are measured by evaluating areas such as indoor air quality, resource and energy efficiency, customer satisfaction, and building and material durability.

A whole-house approach requires that every change made to an existing home be considered in the context of its interaction with the building envelope, mechanical systems, landscaping, neighboring houses, orientation and climate. [See "Actions for optimizing home performance on (almost) any job"] It ensures that you're taking every step you can to maximize the performance of the home while doing no harm to the structure or occupants.

To avoid doing harm, you must start with a good understanding of building science. Lack of education has resulted in many of the health and mold issues we see in homes today. For example, in the 1970s, builders made homes too airtight with overuse of airtight drywall, extensive vapor retarder application, caulking and adhesives, and higher-performing windows. These techniques increased energy efficiency but weren't undertaken considering the impact on the rest of the house, says Courtney Moriarta, executive director of the Building Performance Institute in Malta, N.Y. "These strategies resulted in a number of issues with heating systems back-drafting," she says, "as well as moisture issues that we're still seeing today."

1. It's not easy being green: Get educated

In new homes, it's simple to define acceptable levels of home performance and to design and build to those standards. In existing homes, improving home performance involves evaluating current home performance, determining weak points and then developing cost-effective strategies to address those points. Achieving the same level of performance might mean a reasonable effort in one existing home and an unrealistic effort in the next.

"It's been scary for a lot of contractors to take on because taking on any one part so dramatically impacts another, and they simply don't understand the science and principles behind the approach," says David Grubb, owner of David Construction in Berkeley, Calif. He helped develop the San Francisco NARI chapter's Certified Green Building Professional program.

A number of programs that address whole-house performance in remodeling are popping up around the country. Some certify projects based on checklists; others certify individuals based on their completion of educational programs. There are also several federally funded research initiatives to evaluate better approaches to increasing home performance without dramatically increasing upfront cost.

2. Testing, 1, 2, 3

Understanding and employing solid analysis when you step into a home saves you endless headaches and provides you with a far more efficient (and therefore more profitable) method for approaching your work. "We try to give people some baseline for making decisions so they can identify problems coming in the door instead of causing problems going out the door," Moriarta says.

An existing home's performance can be tested using a number of methods. [See "Diagnostic tools for analyzing home performance"] This includes, first and foremost, a thorough, educated visual inspection. Key to this is understanding and looking for visual clues, such as moisture, cracks or settling, that need further diagnosis. It's important to check areas that people don't normally enter, such as attics and crawl spaces. Finally, as the Building Performance Institute says, "Test in and test out." In other words, make sure what you had intended to do worked by testing the final product as well. If nothing else is done in the home, combustion diagnostics and pressure tests should be done to ensure occupant safety and health.

Also remember that diagnostic tools can be hands-on tools that might assist you in convincing homeowners to do additional work.

3. Put first things first

How do you prioritize activity cost-effectively? No matter what kind of job you're doing, start with anything that affects occupant health and safety and then worry about the home. "Combustion appliances are the occupants' number one enemy if not functioning right," Moriarta says. "Moisture is the building's number one enemy."

First, ensure that all combustion appliances (furnace, water heater, gas stoves, dryers, fireplaces) are performing appropriately. Next, take care of moisture, from leaks (from pipes and external sources) to high levels of humidity that might cause mold to grow. Depending on the level of moisture intrusion, you might need a contractor who specializes in moisture remediation. Whatever the case, ensure that all moisture-damaged areas have been cleaned and dried, with water-damaged building materials replaced before attempting additional construction.

Then you can address energy efficiency and comfort issues with strategies for insulation, airtightness and mechanical systems. In a whole-house approach, comfort and efficiency can go hand in hand.



Improving Energy Performance and Durability


After remodeling, the Green House improved its HERS score to 89. It houses the Sustainability Institute, an organization that educates homeowners on sustainable remodeling approaches.

Completed in 2002, the Green House renovation project in North Charleston, S.C., is helping scientists with the Department of Energy's Building America program evaluate whole-house approaches to increasing energy performance. IBACOS Inc. planned and managed remodeling work on the 870-square-foot home, which is roughly 60 years old.

Before the renovation, the home had a HERS (Home Energy Rating System) score of 57. Energy and durability improvements focused on:




  • building envelope improvements - increased insulation on exterior walls (R-13) and ceilings (R-38); new double-glazed, low-E windows; and air sealing.



  • the addition of mechanical ventilation and a dehumidification system.



  • a high-efficiency heat pump system, located within the conditioned space.



  • a new, insulated and sealed duct system.



  • a continuous drainage plane with integrated flashings.



  • an insulated, unvented crawl space with a continuous vapor barrier.

    After the work was done, the home reached a HERS score of 89. The home is being monitored for energy performance as well as dehumidification performance.



    Diagnostic Tools for Analyzing Home Performance


    A blower door test measures leakage through the building envelope.



  • Carbon monoxide detector: to determine carbon monoxide levels for occupant safety as well as your own. Approximate cost: $500-$1,000.





  • Digital pressure gauge: to measure drafts and determine how much depressurization of the home is caused by exhaust appliances when they're running (which can suck bad gases back into the house). Approximate cost: $600.





  • Blower door: to measure leakage through the envelope, and used in conjunction with a pressure gauge to track down where leaks are occurring. Approximate cost: $2,000, including the pressure gauge.

    A duct blaster tests leakage in existing duct systems and certifies the quality of a new installation.



  • Duct blaster: to determine duct leakage (according to the Building Performance Institute, in some cases it can be used, with a special frame, as a blower door test). Approximate cost: $1,000.





  • Infrared camera: expensive, but shows all of the thermal issues and provides a great visual tool to use with homeowners. Approximate cost: $5,000-$6,000 for adequate model; $20,000 for top-of-line.

    For more information on these tools, try The Energy Conservatory at www.energyconservatory.com.




    Certified Green Building Professional courses, www.sfbanari.com

    The San Francisco NARI program educates and certifies remodeling contractors on the basics of green building, whole-house approaches to remodeling and how to sell the benefits of green building and home performance to homeowners. "We can't keep up with consumer demand for certified green building contractors," instructor David Johnston says. The four class modules are Energy Efficiency, Resource Conservation, Indoor Air Quality, and Developing and Marketing a Green Business. NARI plans to roll out the program nationwide.

    Building Performance Institute, www.bpi.org

    The BPI partners with affiliates around the country to provide training. BPI-certified contractors are tested on their building science knowledge as well as their ability to apply BPI's standards and perform the inspections necessary to diagnose building performance. BPI's programs certify contractors in broad areas of understanding as well as in specific areas such as heating, cooling or shell.

    Energy and Environmental Building Association Institute, www.eeba.org

    The EEBA Institute of Building Construction Technology features a building-science- and practice-based professional development curriculum. Although designed specifically for new construction, it's a great educational resource for new technologies and innovations, the latest research findings and the basics in building science.

    BuildIQ, www.buildiq.com

    BuildIQ is an online training company that focuses on delivering construction best-practice information. Although designed for production home builders, the material in its Building for Performance course gives the basics of building science necessary to understand whole-house approaches to any building, old or new. Other courses focus on best practices in specific construction areas.

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