Low-tech Magazine

The solar envelope: how to heat and cool cities without fossil fuels

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Architects all over the world have demonstrated the usefulness of buildings which are heated and cooled by design rather than by fossil fuel energy. What has received much less attention, however, is the possibility of applying this approach to entire urban neighbourhoods and cities.

Designing a single, often free-standing, passive solar house is quite different from planning a densely populated city where each building is heated and cooled using only natural energy sources. And yet, if we want passive solar design to be more than just a curiosity, this is exactly what we need. Modern research, which combines ancient knowledge with fast computing techniques, shows that passive solar cities are a realistic option, allowing for surprisingly high population densities.

Illustration by Diego Marmolejo for Low-tech Magazine.

The bright future of solar thermal powered factories

Most of the talk about renewable energy is aimed at electricity production. However, most of the energy we need is heat, which solar panels and wind turbines cannot produce efficiently. To power industrial processes like the making of chemicals, the smelting of metals or the production of microchips, we need a renewable source of thermal energy. Direct use of solar energy can be the solution, and it creates the possibility to produce renewable energy plants using only renewable energy plants, paving the way for a truly sustainable industrial civilization.

The ugly side of solar panels

New research shows, albeit unintentional, that generating electricity with solar panels can also be a very bad idea. In some cases, producing electricity by solar panels releases more greenhouse gases than producing electricity by gas or even coal.

(Picture: Sungazer)

Solar powered cars

If racing cars can drive on solar energy, then why do normal cars still need fossil fuels?

Around 30 cars race 3,000 kilometres across the Australian continent in the “World Solar Challenge”. Solar cars are electric vehicles that generate their own electricity, by means of around 6 m² of solar panels installed on their bodywork, and a series of linked up batteries that serve as a fuel tank. If we want the car to survive in the longer term, it should become slower and lighter again, trimmed to the efficiency of solar panels and batteries. (Picture: Venturi Astrolab)