The way some people are chasing energy efficiency retrofits you would think there was a pot of gold at the end of the net-zero rainbow. Too bad; the pursuit is just as foolish and unproductive as chasing rainbows in the first place.

Blasphemy, some might say. How can an environmentalist not throw himself on the energy retrofit bandwagon? Easy. I follow the four laws of Ecology: 1. Everything is connected; 2. Everything goes somewhere; 3. There is no free lunch; and 4. Nature bats last. Understanding the home is a system within a system within a system that operates under more complex lines of impact than BTUs consumed, I understand the danger of strapping blinders on and pursuing a single-minded goal without considering the systemic implications of such actions.

Wasted Energy ?

Knowing the dangers associated with the energy retrofit pursuit, I posed the question “What is a safe deep energy retrofit” to a number of distinguished folks around the country. Pat Huleman, at the Cold Climates Research Center at the University of Minnesota replied “I wondered if this was an oxymoron.” He continued, “Too many homes are either too close to the cliff or too fragile for one-size-fits-all solutions of the deep energy magnitude. Put another way: In many existing homes the energy waste is covering a multitude of sins.”

Huelman’s sentiment was similar to what I heard at Joe Lstiburek’s Building Science Symposium by a senior researcher from the Fraunhofer Institute in Bavaria (They do the kind of intense testing and research on building material and assemblies that makes manufacturers nervous and code officials confused.), who said, “Buildings work just fine until you insulate them. Get rid of the insulation and you eliminate the problems.”

I was chided by remodeler Paul Eldrenkamp for proposing that we should ever consider anything other than a ‘safe’ remodel. Paul Morin with the Energy Center of Wisconsin, and one of the most knowledgeable folks on the subject of combustion safety in homes put it succinctly “No safe renovation is cheap. A safe renovation: one that improves durability, has no adverse effect on occupant health, reduces resource consumption to long-term sustainable levels. If you are willing to forego any of those criteria it gets a lot easier and cheaper to renovate”

The Myth

Solar panels on every rooftop, wind turbines in every yard, and home performance contractors will give us energy independence, put money in our pockets, save the planet, and bring about world peace. Right. Solar panels are primarily manufactured in China. Only one high-efficiency solar panel from Japanese manufacturer Sharp meets the 70% requirement to be labeled ‘made in the USA.’ The secret sauce in Photovoltaics is the 99.999% pure Silica crystal discs, which require massive amounts of energy and a bevy of nasty chemicals to scrub the impurities out. This results in some nasty sludge that gets dumped in lakes and rivers in countries with lax environmental controls. When the primary energy source for making the solar panels is coal, then we must also account for a few human fatalities, smog, water pollution, and the release of mercury into the food chain from coal mining. (For those that bemoan nuclear energy, bear in mind that mercury has no half life.) Estimates on the carbon payback alone from solar panels range from eight to 15 years. Kyocera warranties their PV panels for 10 years at 90% and 20 years at 80% rated power output. No free lunch.

Insulation is hardly a silver bullet either. Walls account for roughly 18% of a home’s performance when modeled. Homes built before the 1950s feature windows that were generally not flashed. Bulk water would routinely enter the wall cavity in addition to moisture driven from either side of the enclosure. However, as Professor Huelman accurately points out, the energy we were using to heat our homes was actually dealing with this issue by driving the dew point outside of the enclosure and providing the heat needed to dry out the assembly. When we insulate we reduce the drying potential of the home, and in a situation where bulk water is actively entering the home this is a very dangerous proposition. Is the $100 per heating season that you might save worth the risk?

The Wrong Yardstick

In the world of deep energy retrofits, nothing is more attractive than the “perfect wall” assembly. The creative and memorable acronyms vary (PERSIST – Pressure Equalized Rain Screen Insulated Structure Technique, REMOTE – Residential Exterior Membrane Outside Insulation Technique, ETMMS – Exterior Thermal Moisture Management System), but the concept is the same. Remove the insulation from the wall cavity, wrap the home with a membrane, put 3-4 inches of extruded polystyrene (XPS) on the exterior, and then a cladding. Apart from being insanely expensive, horribly complicated, and still the subject of graduate studies and taxpayer-funded laboratories, it carries a serious problem with it.

Last year Environmental Building News reported on the global warming potential of insulating products like XPS. The research reported that conservatively (figuring on only half of the blowing agent escaping the material and no further degradation of material) that adding 2 inches of XPS to a home with existing R-13 insulation would bestow a 60 carbon penalty on the home. In other words, in simply creating the XPS or spraying closed cel foam on the home, it will be at least 60 years before there is any greenhouse gas savings.

In focusing our conversation on BTUs and watts saved, we may in fact be making the situation worse. We already know trying to show ROI with dollars for anything other than the most basic of operations is a losing proposition, and measuring kilowatt hours and BTUs results in releasing more catalysts into the atmosphere. What is needed is a systems approach to reducing emissions that measures GHG (green house gas) released as well as total environmental impact of the fuel source. The data isn’t hard to find, but it doesn’t allow for a one-size-fits-all policy for the country and it points an ugly finger at some states that would be politically unpopular.


Noise pollution from airplanes in Minneapolis resulted in thousands of homes receiving new windows, insulation, and air conditioners. Hundreds of homes were damaged as a result of improperly installed insulation and windows. Worse yet was the discovery that major appliances were back drafting. Combustion spillage, as it is called, was observed in 20% of the homes PRIOR to tightening up the home. The program came to a full halt as a protocol to ensure the safety of the occupants was developed. For those folks who receive BPI training today, understanding and testing for combustion spillage is standard practice, but for remodelers installing windows, insulation, new building paper, fan fold insulation, and siding, it is not. I had the opportunity to observe first hand as a remodeler reduced air infiltration by over 50% through the installation of new building paper and siding, new windows, and minimal air sealing. The result was that every appliance in the home failed the worst case combustion spillage test and dumped flue gas inside the home.

Observing homeowners purchasing and installing these materials with little to no training suggests remodelers may have plenty of work in the years to come as homes rot from the inside, but the bigger concern is the health and safety of the occupants. How many people--remodelers and homeowner’s alike--understand the risk they are placing on themselves and their families?

Want more to worry about? Cheap cellulose insulation often found at the big box retailers sometimes uses ammonia sulfate which is both corrosive and produces an odor closely resembling cat urine when wet. Hardly a sustainable or healthy solution.

Risk vs Reward by the numbers

Buildings consume roughly 40% of the energy in this country according to the DOE, and homes account for roughly 50% of that usage (or 20% of our nation’s energy consumption). Buildings also consume roughly 76% of the nation’s electricity. If we assign that same 50% to homes, then 38% of the nation’s electricity is consumed at home. If the majority of housing’s energy use is electricity, and the majority of homes that have a heavy heating demand are using a fuel source other than electricity to provide that heat, what is the value of increasing insulation? The hard truth is that we can reduce GHG emissions from homes by 40% without spending a dime, rotting out our homes, or creating dangerous indoor environments, by simply changing our behavior towards electricity consumption.

Doing the wrong thing the right way may be worse than doing nothing at all. So what are energy enthusiasts to do? Where do we start and stop insulating? The answer is different for every home in every part of the country, but there are some general rules that you can follow that will reduce the likely hood of making things worse.

  1. Test in, test during, test out: Blower door, infrared scan, radon test, and combustion spillage test.
  2. Less is more: Limit insulation activities to attics, rim (band) joist, and weight pockets of windows.
  3. Replace atmospherically venting appliances with sealed combustion direct vent units: Most importantly, do not replace a boiler or furnace and orphan the water heater. If replacing a boiler, consider combination units like those from Eternal and Navian that provide both domestic hot water and heating hot water.
  4. Know your insulation types: Fill window weight pockets with low density foam only. No fiberglass, cellulose, or high density foam
  5. Think “assembly” not “parts”:The wall is an assembly. The parts are not interchangeable or easily isolated. If you want to insulate the walls of a 1920 brick or stucco home with abbreviated or non-existent eaves, you must first remove the cladding material and create a continuous drain plane that integrates with the new windows you are installing. The cladding should then be re-installed with a 3/8-inch air space between it and the WRB (weather resistant barrier).
  6. Think GWP:Use insulation types that have the lowest GWP possible while remaining appropriate for the assembly, e.g., low-density spray foams, blown in batt, blown cellulose.
  7. Think twice before you do anything

Michael Anschel, a nationally recognized expert on Green design, remodeling and building, writes, trains, and speaks for various publications and events around the nation. He is the owner of Otogawa-Anschel Design-Build a award winning nationally celebrated design-build firm, and CEO of Verified Green Inc. which consults with Local Government, product manufacturers, suppliers, builders, and architects on Green building. Michael led the effort to develop MN GreenStar, and now serves as Technical Research and Development liaison on the board of directors.