After Weatherization

Posted on September 25, 2015
Posted By: Rick Barnett

Residential energy codes were established to cut energy use by strengthening or “weatherizing” the barrier between outside and conditioned interior space.  Weatherization reduces energy for “space conditioning”, the largest part of residential energy use, and the least affected by US efficiency programs.  Weatherization products are typically installed as a system, between ceiling and wall framing members.

Programs to conserve residential energy began in the 1970’s with public assistance crews weatherizing leaky older homes.  Most retrofit insulating occurs around ceiling joist, since they are more easily accessed than wall studs.  Since the square footage of the top floor ceiling is always less than the square footage of walls, the attic emphasis leaves most of the thermal shell untouched.  Nonetheless, this approach to weatherization is still the standard for community, government and utility efficiency programs. 

The 1980 USDOE report, “Low Energy Futures for the United States” (DOE/PE-0020), didn’t mention weatherization in a glimpse of future buildings.   Rather, the report states: “improved design and construction incorporating passive solar, superinsulation, and double envelope construction can greatly reduce energy requirements” (page 25).

The lofty goals from 1980 are still being researched.  In practice, the thermal shell is still framed and weatherized in a fashion that leaves an unconditioned attic just inches above the living space and walls filled with thermal defects such as studs, pipes, wires, ducts and electrical boxes.  This design results in low thermal performance and high energy waste.

In contrast to unchanged weatherization techniques, most US efficiency programs include leading edge technology with smart buildings and controls, efficient HVAC and appliances, and low watt lighting.  Weatherization is an anomaly in an industry filled with rapid technology development.

Fortunately, a more effective “next step” for a thermal upgrade is available:  the structural and thermal shells can be merged by installing a continuous seal over the roof and walls.  A thorough thermal wrap eliminates energy-wasting defects, and can produce “Thermal Optimization”, the level of thermal performance that requires the least amount of space conditioning energy.

Shell improvement is the only type of efficiency upgrade that can be evaluated with actual measurement, rather than estimated savings from product installation, such as windows, lighting, appliances and thermostats.   Numerous “energy performance scoring” systems are available to evaluate a home’s propensity to consume space conditioning energy.  From this measurement, reduced consumption and emissions can be determined and monetized over the life of a home. 

A program to optimize customer homes has increasing value to utilities faced with emission constraints, peak overload and plant closures.  The feasibility of a utility Thermal Optimization program is based on local variables such as energy price, contractor rates, topography, vintage and size of homes, etc.

Optimization can be produced by existing contractors and suppliers:  no new technology has to be developed.  Siding, spray insulation, and rigid insulation contractors already have the skill to achieve this level of performance.  If embraced by the utility industry, the per-house price for Thermal Optimization would quickly be driven down.  This would be similar to the cost difference between a custom and a production home.

Thermal Optimization cuts unnecessary waste and better prepares a home for more extreme weather.  If embraced by the utility industry, Thermal Optimization would re-vitalize the construction and insulation industries.  Countless local jobs would be created:  nothing can be outsourced.  Picture neighborhoods across the country, being systematically prepared for the 21st century.

The economic potential of Thermal Optimization is evident from US Census Bureau facts about the 130 million US homes:

  • - 44% of US homes were built before 1970
  • - The median square footage of a single family home built in the 1960’s or earlier stands at 1500 square feet
  • - The median square footage of single family homes built between 2005 and 2009 stands at 2200

From my experience as a retrofit contractor,   I estimate the per-house cost in a utility-financed Thermal Optimization program at $11,000.  My assumptions are as follows:

  • - “Average” utility customer house:  1600 square feet, single story, built 1970
  • - “Wrap” technology for the estimate:  spray insulate roof framing from plate line to ridge, cover exterior walls  with rigid insulation

At this price, Thermal Optimization could reduce more carbon per investment dollar than smart technology, rooftop solar or customer engagement.  While thermal upgrades are currently the smallest part of utility efficiency programs, demand-side investments could be attracted to the measurably significant and permanent result of Thermal Optimization. 

Authored By:
Rick Barnett has a B.A. in psychology (UCSB) and an Interdisciplinary Master’s in Environmental Management (Oregon State University, 1981).  Before becoming a builder, Rick introduced the Oregon waste management industry to recycling in 1976, and over the next few years convinced many to offer recycling as a service.  Oregon has been a national leader in recycling ever since.Rick started Green Builder in 1996, and was recognized in 1998 by Sustainable

Other Posts by: Rick Barnett

Efficiency Gap - March 07, 2016
Energy Asset - January 21, 2016
Energy Customers - April 08, 2015
Saving Energy - March 10, 2015

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