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.

Medieval smokestacks: fossil fuels in pre-industrial times

The history of energy use in human civilisation is generally summarised as follows: from Antiquity until the start of the Industrial Revolution, people made use of the manual labour of both animals and humans, as well as biomass, sun, water and wind.

Next, all these renewable energy sources were replaced by fossil fuels: first coal, and later oil and gas. Uranium completed the picture in the second half of the twentieth century.

While this historical summary is basically correct, there were some - rather important - exceptions. Almost all of the leading economies in Western Europe during the last millenium relied on a large-scale use of fossil fuels such as peat and coal.

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.

Insulation: first the body, then the home

You could fill a library with reports and books describing the importance of energy-efficient heating systems and home insulation. However, not a word has been said or written about the energy savings potential of clothing, even though there has been a lot of progress in this area too. Modern thermal underclothing offers the possibility to turn the thermostat much lower without sacrificing comfort or sex appeal. The potential energy savings are huge; the costs are almost nil.

This article explains through science and statistics how to maintain thermal comfort at any given indoor temperature using only clothes.

Wood gas vehicles: firewood in the fuel tank

During the Second World War, almost every motorised vehicle in continental Europe was converted to use firewood.

Wood gas cars (also known as producer gas cars) are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars.

Rising fuel prices and global warming have caused renewed interest in this almost-forgotten technology: worldwide, dozens of handymen drive around in their home-made woodmobiles.

Rings of fire: Hoffmann kilns

About a year ago we presented a medieval building technique that could save large amounts of brick and thus embodied energy in construction: timbrel vaulting. Turns out that there is also a 19th century brick and tile production technique that is surprisingly energy efficient: the Hoffmann kiln, a giant version of the medieval oven stove.

Sunbathing in the living room: oven stoves and heat walls

Oven stoves are greener, more efficient, healthier, safer and cosier than all modern heating systems. Why are they gone and how do we get them back?

An oven stove is a very efficient and robust oven that radiates heat all day. In the US it was introduced only 20 years ago, but in Europe the technology is almost one thousand years old. Especially in Russia, Scandinavia and Central Europe the oven stove has a long and rich tradition.

In the 18th century, several European governments financed research to improve the technology, as a way to overcome an acute shortage of firewood: ecotech before the term existed. However, its further development and distribution was thwarted by the arrival of coal, gas and oil. Oven stoves are large, heavy and slow, but they offer so many advantages that they – again - deserve to be subsidized by the government.

Leave the algae alone

While the first generation of biofuels is wreaking havoc on the environment and the food markets, the second generation is set to make things even worse.

Since it has become clear that ethanol and biodiesel made from food crops are doing more harm than good, the hope for finding a substitute for oil has shifted to algae and cellulose. If we can believe the advocates of this ‘second generation’ of biofuels, these combustibles will deliver way more energy than it takes to make them, without threatening the world’s food and water supplies. Upon taking a closer look, however, this is very hard to believe. They might even cause bigger problems than biofuels made from food crops. Maybe this time around we could sort this out before the damage gets done?

Heat your house with car tyres and earth

Energy hungry America teaches the world how to build ecological houses.

A dirt cheap and 100 percent ecological house that has all the comforts of an ordinary home, without being connected to the electricity grid, waterworks, sewer system or the natural gas network. It does exist, but in most countries, building one is not allowed.

An Earthship is a completely self-sufficient house that has a natural temperature regulation, without the use of a heating system. The building also generates its own electricity, collects and filters its own drinking water and cleans its own effluent water. The house is partly buried into the earth and is constructed mainly with waste materials; car tyres, aluminium cans and glass bottles. This low-tech building approach is ecologically as well as economically advantageous.

This autumn, the British coastal city of Brighton approved the construction of 16 Earthships. It’s the first time that a European city council has given builders the green light to mass construct this radical ecological housing form. In the United States nearly one thousand Earthships have been built, most of them in the desert of New Mexico. (Pictures: Michael Reynolds)