SFH is not sustainable. As the population keeps growing every year. If everyone wants a SFH, how much land would that eat up? Then there's the transportation. We need to build more roads and up keep them. We need to put in more transit or else everyone would need a car and everyone will have to drive in order to reach their destinations. If instead of stacking up vertically, we stack horizontally, there will be dire consequences. It will take much longer to get to places, cost more to build transit. Heck we might not need so much public transit if everyone is so sprawled because everyone would be driving a car. We'll need more fossil fuel. The prices of oil will sky rocket even more. We will pollute the earth with exhaust fumes. We'll get rid of our forest so we can build more SFH.
And don't forget the loss of farmland which will mean more fuel to fly or truck in (more roads) food from elsewhere. The driving of kids to school and playdates. The construction of huge and hideous paved-over power centers which discourage walking because of the distances and the certainty that some idiot will run you down.
Garbage trucks don't have to go around to 200 SFHs the way they do for the equivalent number of highrise units. A couple of dumpsters and that's it. That's less idling and fewer expensive short hauls in terms of fuel consumption, i.e. fewer fumes.
More roads require more lighting, i.e. more energy.
More roads require more street cleaning, snow clearing and maintenance, i.e. more energy.
More houses mean more utility poles, fewer trees --and, after last year's ice storm, trees, which are good for the environment, are now seen as the enemy.
The list goes on.
I agree that statistical data are meaningless unless you compare apples to oranges in terms of weather, density, age of housing stock, availability of transit etc.
As some of you know, I am treasurer of our condo building, the one we moved into two years ago after selling our SFH.
Now, I can sit down and work out the precise numbers -- I have one of those worthless MBAs -- but life's too short. Suffice to say that my best estimates show that our hydro/heat/hot water costs as a portion of our monthly fees are lower than what they were in our house, even after I account for the loss of 900 SF of living space in the downsize and the increase in utility rates since 2012. I suppose I could factor in the shared walls which would mean less heat loss but our house was a semi and I am certain our windows were better than the ones here.
Our share of utility costs, for the record, cover our share of the lighting and ventilation of the common areas, the elevator operation, the saunas, the heated indoor pool etc. And this is one of the older condos in town so, as far as insulation goes, she ain't the best. Yes, hydro gives us bulk rates but they are not much better than what the typical SFH owner pays.
There is no way that SFH living is more sustainable unless you're living on a tent off the land, growing your own food and kayaking everywhere.