A Key Distinction

Posted Tuesday, May 22, 2012 in Sustainable Maine

A Key Distinction

by Paul Kando

Consider three cars. Car #1 seats 5. Its steel body has a conventional shape we are used to. It has a big Otto cycle engine. Decorative trim identifies it as “late model”. It gets 18 miles to a gallon of gasoline on average.

Car # 2 also seats 5. It has a lighter, aerodynamic aluminum body. It is powered by a small Atkinson cycle engine and an electric motor-generator. It gets over 52 miles to the gallon.

Car #3, an aerodynamically shaped two-seater, is built of light weight carbon fibers. One version runs on diesel fuel, another is a plug-in electric. Both get the equivalent of 235 miles to the gallon.

Now take two houses. House #1 is “code-built” – 2x6 framing, “R-19" insulation, etc.  It has features that sell houses – traditional look, clapboard siding, attractive windows, nice amenities -- but it also leaks like a sieve, with over 8 natural air exchanges per hour. Its walls typically have a true insulation value of only R-11 to R-13.5, depending on how well the batts were installed.

In contrast, House #2 was designed to use no more than 4,758 Btus of heating energy a year per square foot of floor area, and no more than 38,063 Btus for all purposes. It has no conventional heating system. A ventilator recycles overs over 80% of the heat from the exhausted air. This house is tight, with a natural air exchange rate of 0.6 per hour.

Even without more detail it is obvious which of the above products perform better. Those must be also the most expensive, right?

In fact, models of Car#1 often cost more to buy. And, all other things assumed equal, driven 15,000 miles per year using $3.90 a gallon gasoline, the annual fuel cost will be $3,249 for Car #1, $1,123 for Car#2, and $250 for Car#3. Compared to Car#1, Car #2 will save $2,126 per year and Car#3 will save $2,999 in fuel cost alone.

How can Car#3 be less expensive than either of the other two when carbon fibers cost far more than either steel or aluminum? Carbon fibers are also tougher, more crash resistant and much lighter. Because it weighs less than 800 lbs, Car#3 requires a smaller, less expensive engine, drive train, battery bank, etc. It is also more economical to drive.

Similarly, while a conventional Maine house (#1) burns 1,000 gallons of oil (or equivalent) per year on average, a Passive House (#2) uses 100 gallons or less. Leaving aside the potential zero energy option and assuming all other things equal, at $3.70 a gallon for oil, House #2 saves $3,330 per year in heating costs alone. So House #2 with its thicker walls, R-60 insulation, more expensive windows, etc., must also be more expensive to construct? Not really: This house needs no conventional heating system and insulation costs far less than mechanical systems. Price-competitive with a similar conventional house, House #2 saves tens of thousands of dollars in operating costs over the mortgage period.

What distinguishes innovative products like #2 and #3 above is the integrative design they embody. They are designed to achieve a predetermined outcome, rather than least-cost sales appeal. This is a systemic difference: outcomes – performance – depend foremost on physics (properties of materials, laws of nature) rather than “market considerations”. Integrative design works with the laws of nature to ensure superb performance at minimal cost.

In contrast, conventional products are essentially standardized components assembled to suit a conventional manufacturing or construction process designed to satisfy a cultivated “demand” at minimal cost. They meet minimum expectations over a minimum time period (after which buy a new car or an extended warranty). Conventional wisdom speaks of diminishing returns – after 6" of insulation each additional inch results in a smaller benefit. Products #2 and #3 argue otherwise: it is the appropriate combination of features that provide the greatest benefit. Integrative design is a source of expanding returns on investments in energy efficiency, to borrow a phrase from Amory Lovins.   

How competitive can a car maker or builder be, trying to graft new knowledge onto an obsolete, Victorian-era industrial process? Trying to minimize my home’s energy consumption, should I think conventionally, i.e. spend as little as possible on “good enough” measures, or invest optimally for maximum return? To decide what’s appropriate for my circumstances, what I need most is reliable information. Stay tuned.

blog comments powered by Disqus