Personal Writings

I recently attended a workshop convened by the Urban Sustainability Directors Network, USDN, on the topic of sustainable consumption. One of the issues that repeatedly came up was how to address income inequality while also promoting sustainable consumption. To pursue either of these two big questions is a big undertaking already, but the two together are mind boggling. So I took some time to educate myself on the relationship between household income and its GHG footprint (the latter standing for energy and material consumption).

My key finding is that household income is a strong predictor of that household’s carbon footprint. This correlation is consistently and unambiguously reported in several recent studies in the US and Europe. As shown in the figure from the 2014 report by Center for Global Development among the US households the correlation is linear for the bottom 80% of income categories (up to approximately $120,000 for a family of four) and accelerates above it. The greatest acceleration is among the top 2% of income. Stated differently: the more we earn the greater our GHG footprint is, with households earning more than about $120,000 engaging in more carbon intensive lifestyle choices and amenities. One caveat is that it seems to me that the GHG footprint estimates for households in the top 5% income bracket are rather uncertain in all the studies I examined, but for the households in the 95% category (up to $200,000) the data seem to be strong.

With this knowledge, I tried the following thought experiment. Suppose we were to decrease income inequality by reducing the number of households with the extremes of income (at the top and the bottom) and increase the number of households in the remaining categories, say between 20 and 80% income brackets. How would it change the total consumption-based GHG emissions? The answer is: they would remain more or less the same or because the top earners seem to be more GHG intense per dollar spent than the rest of us, perhaps a little lower. In another thought experiment consider what would happen to the total national GHG footprint if we reduced the proportion of households in the lowest income bracket by moving them into the middle-income category, without touching the households in the top category. The answer is that the total emissions would increase.

This is a disturbing thought in light of the questions posed by the Urban Sustainability Directors: raising the income of those who most need it will result in greater total greenhouse gas emissions unless we simultaneously reduce the income at the top. The latter is not only a political problem but also is largely outside the jurisdiction of municipalities. And come to think of it, increasing the income of the bottom earners is also for the most part outside the options available to municipalities. So what can municipalities do?

One idea that comes to mind is that instead of thinking of income, which households seem to be always converting into carbon emissions, the municipalities can think of providing quality of life (and keeping an eye on GHG emissions while doing so). The case in point would be to provide affordable high-quality middle-class housing in locations conducive to good life that is also extremely energy efficient. Extremely energy efficient construction, including the so-called “passive house” construction, is a technical challenge that has been already solved, but most developers and municipalities do not practice it. I will not go into this matter in this posting. Rather, I want to focus on affordable middle-class housing and good life. To pursue it, municipalities will need to think outside the box of the dominant model of a private developer and token subsidised units for the poor. In my next post, I will describe an amazing housing project in New York City, known as Penn South, that delivers high quality of life, affordable housing and a thriving community life on a modest GHG footprint in the centre of one of the most expensive cities in the world.

My home city of Newton, Massachusetts, likes to think of itself as green. We have a high recycling rate, shun the use of chemicals to control pests, support community gardens, take an aggressive stance toward water management, advocate for solar roof installations, and recently we even banned the use of plastic shopping bags in supermarkets. But the issue that unites us like no other is energy efficiency.

So when the political opportunity opened up in 2010 Newton adopted a building code that requires higher energy performance than would be achieved in constructing a comparable house according to the general Massachusetts building code. This so-called “stretch code” set the bar at a performance level 20% higher than the baseline. This was a modest step toward energy efficiency, nothing like the building codes that have been adopted by several European countries, but since in Newton about 40% of total greenhouse gas emissions comes from the residential sector this was a notable improvement.

In order to track the progress of the Stretch Code my colleague and I have recently examined the energy performance of several hundred residential houses built since 2010. The good news is that their performance was 30-40% better than the baseline. This means that once the construction industry adopted different materials and practices it was not a “stretch” for them to produce much more energy efficient buildings (and not a single complaint was filed!). But when we looked at the specifications of these new houses we discovered that in almost all cases the new construction entailed replacing an older smaller house, somewhere around 2000 s.f. in floor space (roughly 200 s.m.) with a huge 4000-6000 s.f. mansion. My very rough back-of-the-envelope calculations show that doubling the floor area of a house increases the surface area of its envelope (and thus the heating and cooling energy demand) by about a factor of 1.8 while the factor for tripling the house size is about 2.7. This is what this means in practice: we increase the energy demand by between 80 and 170% owing to size while also reducing it by between 30 and 40% owing to more efficient construction. Stated differently, we are losing ground but at a slower rate than we would without energy efficiency measures.

This phenomenon of tearing down modest but perfectly serviceable middle-class houses and replacing them with luxurious giants is rampant across coveted communities across the country. It goes hand in hand with the disappearance of the middle class. This is a perfect storm: the municipality benefits financially from higher real estate taxes, and in the areas where the cost of land is high mortgage lenders and developers find much greater profit in larger houses. And there is a steady stream of people in the U.S and worldwide with plenty of money, looking to park this money in real estate.

No wonder my efforts to frame the issue of house sizes as that of climate protection and (un)sustainable consumption have been futile. A friend local and politician, a person I respect, recently said to me that being critical of large houses sounds like an envy of rich people. OK, I got the message: do not bring it up. Stick with trash recycling, street lights, and solar panels. And do not disturb our smug Newton certainty of being green by collecting quantitative performance data.