LOW-TECH MAGAZINE

Radiant & Conductive Heating Systems

Most modern heating systems are primarily based on the heating of air. The old way of warming was based upon radiation and conduction, which have the potential to be more energy-efficient than convection.

While convection implies the warming of each cubic centimetre of air in a space in order to keep people comfortable, radiation and conduction can directly transfer heat to people, making energy use independent of the size of a room or building.

However, restoring the old way of warming would not make sense without new technology. Most heating systems from the old days were inefficient, polluting, dangerous and impractical. Today, we have better options available, which can be combined in interesting ways.

Restoring the Old Way of Warming: Heating People, not Places

These days, we provide thermal comfort in winter by heating the entire volume of air in a room or building. In earlier times, our forebear's concept of heating was more localized: heating people, not places.

They used radiant heat sources that warmed only certain parts of a room, creating micro-climates of comfort. These people countered the large temperature differences with insulating furniture, such as hooded chairs and folding screens, and they made use of additional, personal heating sources that warmed specific body parts.

It would make a lot of sense to restore this old way of warming, especially since modern technology has made it so much more practical, safe and efficient.

Heat Your Clothes, Not Your House

As we wrote two years ago, insulation of the body is more energy efficient than insulation of living space. Because of its excellent insulating properties, modern thermal underclothing makes it possible to burn the heating at much lower temperatures without sacrificing comfort or sex appeal. The potential energy savings are huge, and the costs are almost nil.

This low-tech insulation strategy can also be applied to heating the body. In use since World War Two, electrically heated clothes have become more effective and comfortable in recent years. While their use outdoors increases energy consumption, heated clothes have the potential to save massive amounts of energy indoors.

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.