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Recently I have been looking at how I heat and cool my own house in Tokyo. Just by simple changes to the shape of it (encouraging cross ventilation, air flow, using passive heating or shielding out sun light etc.) I could cut my energy use 75-100%. Just the shape. Nothing else. 
But thanks to strict zoning laws when it was built, and skyrocketing land prices my house was built to optimize only physical space use. The zoning laws on my plot stipulated a maximum size (defined as a 3D "box"shape), so a box shape is what was built, not a proper shaped home.
The zoning laws also stipulated a residential street, not commercial. This has since been slightly relaxed, but instead of having a house that could be instantly converted to an office, a first floor shop, a clinic, a craft workshop, a cafe, a bar, etc. I can't easily work here.
So what would I change specifically? I'd ditch the useless balcony and install an engawa, a narrow "sun room" that can be opened up to let sun stream into the interior on winters and shaded during the summer to stop the sun from blasting right into the house. Cuts cooling 50%.
The engawa would also cut my need for heating 75-100% in winter. I would rearrange the back of the house and a couple of the interior walls to give me a through passage of air at night during summer. This would cut the remaining 50% of cooling use. Life without AC in subtropics.
I have tested this by leaving the front door open at night during the peak of summer, opening the windows in the living room and laying down on the floor in the hallway. Not exactly chilly nice around 21 degrees but it pushes indoor temperatures below unbearable 30s. I can sleep.
I would move the house a few meters to the edge of the plot, so that my entrance faces the street directly, or on a stone paved path. This way I can use the street to create a change in air pressure by watering it during hot days: it creates wind from thin air on the hottest day.
And having my house on the edge of the plot would make it easy to open up a shop, run a restaurant, or, considering the tourist attractive area I live in, even rent the first floor out to some fancy French boutique brand or lame American coffee shop chain store. I'd make money.
All of these changes are tiny tiny nudges, picked from a whole battery of time tested methods. They don't require new tech, expensive factories or complicated engineering. All of it can be made by hand by any carpenter's apprentice. I'm drawing on 5000 years of urban experience.
But it does not stop at cutting energy use (and costs), by adapting practical ideas of my ancestors I can cut indoor volatile organic compounds (VOCs), highly carcinogenic, and asthma triggering mold growth: by using earth plasters instead of plastic wall paper on walls...
Instead of vinyl floors I can use lime earthen floors (inhibits mold, repels insects, regulates indoor humidity), wooden floors or tatami mats (also regulates indoor humidity, releasing water on dry days and absorbing it on humid days). All 100% recyclable and sustainable.
Natural materials are also less prone to fire, and when they do burn they burn slowly and do not release toxic gasses to the same degree as modern materials. Structural wood and earth plasters also give you plenty of time evacuate.
