As difficult as it is to envision local conditions around 2040, I would like to attend to the need for people to live healthfully, learn constantly and work fruitfully in very close proximity, sometimes in the very same structure (though then I worry about boredom, noise and cleanliness).
The only idea I can come up with to maximize conditioned air utilization is to make sure that occupied spaces are utilized to the fullest, perhaps 90%. Will we sleep in shifts and massively store sunlight to actually daylight work spaces? Will sleeping spaces double as work spaces in some abodes?
Will whole block groups tall eco-walls all round for vertical agriculture, noise attenuation and to impound ground level cooled air and shaded water? Might such walls be topped with transit lines that zip people from neighborhood to neighborhood, while zero-emission moving sidewalks, bikes, trikes and, as necessary, cars and trucks provide intraneighborhood mobility?
Another direction to explore may follow the fascinating Foreclosed: Rehousing the American Dream exhibition that followed the Buell Hypothesis (http://www.moma.org/interactives/exhibitions/2012/foreclosed/buell_hypothesis) which states that changing the dream will change our living arrangements. I was taken by several teams' proposals (http://www.moma.org/interactives/exhibitions/2012/foreclosed/), but The Oranges, NJ offering by MOS titled "Thoughts on a Walking City" started me thinking about how we could keep out of the heat, get up and exercise year-round and reduce emissions. The central point of their display was to retain good buildings and infill former public rights of way with new, adaptable and vibrant structures that can accommodate walking population+ & economy+ without actually expanding the city. W/"Solid" development within 1/2 mile of transit stations, people riding the rails to "connect the dots" in Houston could visit a myriad of diverse spaces & enjoy each other in tru-eco-mfort.