Harold Orr and the 80% Rule

“You have to tackle the big hunks."

Saskatchewan Conservation House

Saskatchewan Conservation House

That's the Saskatchewan Conservation House pictured above, built in 1977 by the late Rob Dumont and Harold Orr; it was a precedent for the Passive House standard. I thought of Mr. Orr recently when once again I was criticized with a version of a quote from Voltaire: "Don't let the perfect be the enemy of the good." This happens a lot, whether it is a debate about electric cars versus e-bikes, Passive House versus net-zero, or electrify everything versus keeping natural gas. After all, not everyone can ride a bike, or Passive House is fussy and expensive. I am accused of being unrealistic.

I have never thought the accusation was particularly fair because of course, not everyone can ride a bike. Even in the city where bikes have the highest modal share, Groningen in the Netherlands, cycling tops out at 55%. Nor can every building be Passive House. Instead of Voltaire, let's talk about Vilfredo Pareto, the Italian engineer, and economist who noted that "In any series of elements to be controlled, a selected small fraction, in terms of numbers of elements, always accounts for a large fraction in terms of effect." This has also become known as the 80/20 rule: "80% of consequences come from 20% of the causes." Go after the big stuff first. The low hanging fruit. Pareto explained it more graphically (trigger warning for animal lovers):

"If you're Noah, and your ark is about to sink, look for the elephants first, because you can throw over a bunch of cats, dogs, squirrels, and everything else that is just a small animal and your ark will keep sinking. But if you can find one elephant to get overboard, you're in much better shape."
Section of conservation House
Saskatchewan Conservation house

This brings us back to Harold Orr and the Saskatchewan Conservation House. It was designed to be the best, with a continuous wrap of insulation, tight air sealing, careful orientation, and a homemade heat recovery ventilator. It was aiming for a very high standard; so high that it never really caught on until it was discovered by the Passive House founders looking at it and other super-insulated houses. But Orr and Dumont weren't doctrinaire or just looking for the perfect; they realized that there were lots of houses out there.

The Chainsaw Retrofit

Chainsaw Retrofit
Public Domain/ Chainsaw Retrofit. National Research Council/ can this house be saved?

In 1982, Orr and Dumont were at it again, doing what has been called the first "chainsaw retrofit" where they sawed off everything outside of the basic envelope of the house; Dumont wrote:

"In order to allow a continuous air-vapour barrier at the junction between the wall and roof, and to avoid having to wrap the existing eaves and overhangs, it was decided to remove the eaves and overhangs. To accomplish this, the plywood soffits were removed, and the shingles were removed from the eaves and overhangs. A power saw was then used to cut through the roof sheathing and partway through the roof truss eave projection and roof ladder in line with the outside of the existing wall of the house."

They then wrapped the house in a polyethylene barrier and framed it out to add 8 inches of fiberglass insulation all around. It was found to be the tightest house in Canada: "The air leakage of the house as measured by pressure tests was reduced from 2.95 air changes per hour at 50 pascals to 0.29 at 50 pascals, a reduction of 90.1%. Before and after measurements were taken of the space heating requirements of the house. The design heat loss of the house was reduced from 13.1 kW at -34°C to 5.45 kW by the retrofit." Martin Holladay interviewed Dumont for Green Building Advisor and wrote in 2009:

"The global climate crisis now compels our country to face a Herculean task — performing deep-energy retrofits on most existing buildings. “In construction, making decisions is not like solving a mathematical equation,” Dumont told me. “The economics are changing all the time: labor, materials, and energy costs always change. We have nine million existing dwellings in Canada, and over the next three decades I can see virtually all of them being retrofit."

So we don't have to be perfect and knock every house down and rebuild them to Passive House standards, we can do what is essentially a version of the Dutch Energiesprong retrofit wrapping of houses to make them net-zero. But that gets expensive, especially with North American houses with all their bumps and jogs.

Put Pareto to Work

If wrapping an entire house in insulation is too expensive, where do you start? Orr has something to say about that too, in a great interview from 2013 with Mike Henry of The Sustainable Home. Orr complains about all the contractors who just wrap a house in a bit of foam and siding, or as used to do when I was an architect, add insulation and a sheet of stapled 6 mil poly (polyethylene sheets 6/1000 of an inch thick) to the interior. Instead, Orr says you should save your money:

“When you put styrofoam on the outside of a house you’re not making the house any tighter, all you’re doing is reducing the heat loss through the walls. If you take a look at a pie chart in terms of where the heat goes in a house, you’ll find that roughly 10% of your heat loss goes through the outside walls.” About 30 to 40 % of your total heat loss is due to air leakage, another 10% for the ceiling, 10% for the windows and doors, and about 30% for the basement. “You have to tackle the big hunks,” says Orr, “and the big hunks are air leakage and uninsulated basement.”

This is Vilfredo Pareto's elephant; doing the big, easy stuff first.

Pareto Versus Voltaire

Doing an Energiesprong or complete rebuild of every house in North America would take forever and cost the Earth; cutting energy use by 50% or even 80% is achievable by following Harold Orr's prescription. Once you are there, it is not a stretch to switch to an air source heat pump and electrify everything, and you are no longer emitting carbon.

Similarly, converting every internal-combustion-engine powered car to an electric vehicle (EV) is going to take decades, cost a fortune, and each new car has an embodied carbon footprint of about 15 tonnes; just building those cars generates enough CO2 to put us close to 1.5 degrees of warming.

Trip length
Office of Energy Efficiency and Renewable Energy

Whereas bike lanes are probably the fastest and cheapest infrastructure you can build, and almost 80% of trips are less than 10 miles, which is a breeze on an e-bike; 60% are less than six miles, easy on a regular bike. So not everyone has to drive an electric car, and nor does everyone have to drive a car everywhere if there are safe and comfortable alternatives.

Sure, not everyone can ride a bike. Others, like another of my heroes, Jarrett Walker, will say that not everyone lives in the city.


But look at the stats from Statista; fully 80% of the American population lives in urban areas. Pareto and the 80/20 rule says we don't need to worry about the 20% living in rural areas, they can drive electric pickups.

To summarize, it is the EV promoters who are aiming for the perfect, the best of all possible worlds as Voltaire might say, where they keep driving cars while being the enemy of the good enough, bikes and e-bikes. When you take into account that nearly a third of Americans don’t even have driver's licenses, putting so much energy into saving cars makes no sense at all.

We can pretty much fix both our housing and our transportation problems if we think less about Voltaire and more about Pareto, about what works for the largest number of people in the shortest amount of time.