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Buildings and global warming - When it comes to the issue of mitigating carbon emissions, there has been an increased interest recently in finding alternative ways to heat buildings.

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Buildings and global warming - This is perhaps unsurprising and definitely a step in the right direction given the fact that buildings and construction are responsible for nearly 40% of energy-related carbon emissions.

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The status quo - According to the International Energy Agency (IEA), in September 2020 only 10% of energy used for heating was coming from renewable sources.

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The status quo - There is therefore great potential to reduce emissions by finding alternative ways to heat buildings, but unfortunately progress until now has been slow.

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Action needed - The IEA has predicted that the use of clean heating technologies has to double before 2030 if we want a 50% chance of keeping the global temperature increase below 1.5 C (34.7 F).

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Waste body heat -

But things seem to be picking up now, and one interesting alternative heating solution involves harnessing and making use of excess heat that is produced when people move around, which can also be described as waste heat.

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Nothing new - Using the heat generated by human bodies is nothing new, of course: crowded buildings have always enjoyed the fact that human bodies naturally raise the temperature of the place.

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Nothing new -

Busy shopping malls and theaters often capitalize on this lucky fact by turning down their thermostats and saving on central heating in the winter.

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New application - But in a new development, a number of buildings are now heating themselves by capturing and making use of the heat produced by human bodies in another building.

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Parisian apartment building case study - One such building is a large apartment block that is located directly above the Rambuteau subway station in the 4th arrondissement (or administrative district) of Paris.

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Parisian apartment building case study - Much of the heat needed for the building’s 20 apartments and downstairs commercial property comes from the waste heat produced in the station below.

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Rambuteau station - According to Genevieve Littot, climate and energy strategist at the construction company Paris Habitat, the air inside the subway tunnel is around 10 C (50 F) warmer than the air outside.

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Rambuteau station - The reason for the difference in temperature is mainly due to the fact that a lot of heat is generated by the people and trains moving around inside the station.

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How it works - According to Littot, there is a staircase that connects the bottom of the building to the subway tunnel below. The extracted warm water passes through this passageway.

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How it works -

As it moves through this passageway, the hot air passes through a heat exchanger so as to produce hot water. This hot water is then used to heat the building.

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Efficiency - This installation produces 35% of the heat needed to warm the building and also further minimizes carbon emissions through using an efficient district heating system.

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Popular solution - The Parisian apartment building is not alone in its approach; in fact, there are other buildings worldwide that use similar technology to provide heating.

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Popular solution - In Sweden, engineers have worked out a way to harness the body heat produced by the large numbers of people passing through Stockholm’s busy central station.

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Central Station, Stockholm - Before Covid-19, 250,000 commuters would pass through the station each day, producing ample body heat that was ready to be harnessed and recycled.

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Central Station, Stockholm - Currently that heat is used to warm a nearby 17-storey building called the Kungsbrohuset, thus reducing the energy consumption of the building by up to 10%.

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The way it works - According to Roger Bjoerk, technical manager at the company that owns Kungsbrohuset, ocean water is taken in to cool the ventilation system at the station.

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The way it works - The cool ocean water is warmed by the body heat produced inside the station and is then recycled to generate heat in the district heating system.

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Not only body heat - The district heating system also uses heat from other renewable sources, such as geothermal heat and the burning of unrefined biomass (e.g. waste wood or straw).

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Reach - The district heating system then uses a system of underground pipes to distribute the heat to buildings and homes throughout the whole country.

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Potential - According to Ulla Janson, a senior lecturer at Lund University, these district heating systems are very powerful. In 2017, they satisfied half of the heating demand in the residential sector.

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Limitations - Body heat as an alternative heating solution does, of course, have its limitations. Some of the key issues are related to location and space.

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Limitations in cities - For example, the heat source and the building to be heated need to be close enough together that the water does not lose its heat traveling from one to the other.

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Limitations in cities - Littot emphasizes that in Paris the project would be suitable for new builds near metro stations, so that the technology could be built into the planning. In practice, this is rare.

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Limitations by country -

Some are also of the opinion that body heat cannot be the sole source of building heating, particularly in countries where winter temperatures are very low.

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Work in progress -

But recycled body heat nonetheless provides a good contribution to fulfilling energy demand and represents a step in the right direction when it comes to reducing carbon emissions.

(BBC) (Amusing Planet)

See also: The most environmentally sustainable buildings in the world.

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