In recent years, a significant proportion of home-renovation projects aimed at improving energy efficiency have mainly involved adding 10 to 25 cm of highly effective thermal insulation–such as fibreglass or stone-, hemp- or cellulose-based wools–to the outer walls, roof or ground floor. This trend kicked off slowly in France in 1974, when that country’s first thermal building regulation became law (RT 1974) as part of a broad effort to reduce energy consumption following the 1973 oil shock.1 That year, Opec drove oil prices up by a staggering 70%, prompted in part by the war between Israel and its neighbours Syria and Egypt. The aim of that first thermal regulation was to bring the energy consumption of buildings down to 225 kWh/m2/year from 30o kWh/m2/year–the estimated consumption for buildings constructed between 1950 and 1970.
Before 1974, buildings were not insulated at all. Walls–whether made from brick, concrete or plain glass and steel–were monolithic, meaning that the material you see from inside or outside the building is part of its structural system. Well-known examples of monolithic structures using concrete include Brutalist architecture in the UK and Le Corbusier’s Unite d’Habitation. Since concrete is such a poor insulator, with a heat transfer coefficient (U) of around 4.5 W/(m2K), it’s easy to understand why home interiors got so cold in the winter. The U-value quantifies the insulating power of a material in relation to its thickness. The lower the number, the less the material conducts heat and the better of an insulator it is–preventing the winter chill and summer heat from permeating the building. Insulation minimises heat transfer, reducing the need for heating and air conditioning and, ultimately, lowering energy consumption. The next two thermal regulations in France, RT 1978 and RT 1980, led to the use of materials chosen for their low conductivity, such as 3-cm-thick polystyrene, which was added to the brick or concrete supporting structure.
Textile coverings
In a throwback to the tapestries, curtains and rugs that had been phased out at the end of the 19th century, interior walls started to be adorned again with non-weight-bearing textiles in the 1970s. The heat transfer coefficient (U) around this time was estimated at 1.05 W/(m2K). After 1974, the required thickness of insulation increased gradually to around 10 cm under RT 2012, which set a U-value target of 0.5 W/(m2K).
Nowadays, the perils of global warming mean that even stricter building insulation requirements are necessary. The building and construction industry accounts for nearly 40% of global greenhouse gas emissions. One-third of this figure can be attributed to the construction process and the carbon footprint of the materials used. The other two-thirds are a result of the energy consumed by buildings throughout their useful life–primarily for heating in winter and cooling in summer. In 2018, 84.7% of the energy required for heaters and air conditioners came from carbon-based energy sources, which produce the greenhouse gas CO2 when burned. To combat global warming effectively, society will have to switch from carbon-based fuels to renewable energy, such as hydropower, wind power and geothermal power. While renewables account for an increasing proportion of total energy consumption each year (reaching 10.9% in 2018), it may take another 30 years to complete the energy transition. In the meantime, we must focus on reducing energy consumption.
In this, building insulation plays a fundamental role. If walls, roofs and windows are less conductive, radiator-warmed air will no longer be cooled when it comes into contact with outer walls. That means it will take less energy to heat our homes efficiently. Since 1970, energy consumption has been reduced by a factor of 6 in France and 8.5 in Switzerland, and RT 2020–France’s next thermal regulation–is expected to set an energy consumption target of 12 kWh/m2/year, i.e. 25 times less than the 1970 estimate. RT 2020 should bring the country’s standards in line with Europe’s strictest ones, such as Minergie in Switzerland and Passivhaus in Germany, the latter of which requires 20 cm of insulation in pursuit of its heat transfer coefficient target of 0.12 W / (m2K).
Radiators and crimes
Buildings must now be insulated. In new builds, some form of insulating material covered by water-resistant cladding is applied to the exterior surface of the supporting structure. The wool-like material is usually soft and made of fibres interspersed with tiny air pockets, which have a very low heat transfer coefficient. In existing buildings, the insulation can be added on the inside, although there will obviously be breaks where the floors meet the walls. Still, this is the preferred solution where it’s necessary to preserve the original facade, in order to maintain the house’s historical or touristic appeal. In such cases, the insulation is covered with plaster panels. Because this insulation is hidden from view, there is no apparent difference between pre-1973 buildings and modern structures.
But nothing is quite as it seems. These novel insulating materials can be seen as modern incarnations of tapestries, wall coverings and, when placed on the ground, rugs. The use of such materials marks a return to the decorative elements, wall hangings and tapestries of yesteryear, which we ripped off our walls in the loth century in order to “keep our homes clean”, as Le Corbusier said.
This interpretation also sheds new light on how, in the loth century, the Napoleon III and Louis Philippe styles were superseded by the modern look, where all forms of interior decoration gave way to bare, white minimalism. In this, I would emphasise the role played by heating and energy technology.
To understand modernity’s barebones approach, we must look to the invention of central heating and the hot water radiator in 1877. In the second half of the 19th century, coal was widely adopted as a fuel. The enormous amount of energy that could suddenly be unleashed helped to transform western civilisation and gave rise to industrial society. Wood was replaced by mined coal, a reliable fuel that could be burned in basement water boilers. The heated water then circulated through radiators, which, by conduction more than radiation, increased the indoor air temperature. Fossil fuels were also used to run steam engines–invented by James Watt in 1770–and the amount of energy available per capita subsequently increased tenfold. Coal was an easy energy, later joined by gas, oil and, starting in the loth century, nuclear power. These fuels obviated the need for decorative domestic features whose role before the industrial age was to enhance–even so slightly in some cases–thermal and light comfort in homes at a time of low-output heating, cooling and lighting systems. Rugs, tapestries, wall hangings, curtains and fireplaces simply could not compete with coal in terms of thermal efficacy, and they were rendered obsolete. What’s the point in having a tapestry when you can have a radiator constantly fed by extremely hot water produced by a boiler running on carbon or heating oil?
In the l0th century, these outdated decorative elements, deprived of their use value, became superficial ornamentation. The introduction of central heating, electric lighting and, later on, air conditioning, gave architects Adolf Loos, Le Corbusier and Ludwig Mies van der Rohe licence to completely rethink interior design. They were free to remove, take down and throw out decorations whose insulating properties were no longer needed, and promote empty, neutral, white minimalism, devoid of ornamental features.
Loos and the power of coal
Adolf Loos led the attack on ornamentation, starting in 1908. Loos is considered a hero of modernity, but he could also be seen as a champion of coal. For the Austrian architect, all decoration was superfluous, if not downright criminal. He cared little for decorators and valued building work that didn’t change style every three years. His first designs were smooth and white, and his interiors were derided by his critics as nihilistic. One such example is the Café Museum in Vienna: simple and sober, fluid and functional, it consisted of little more than its underlying structure. Radiators removed the issue of thermal comfort from the task at hand.
Loos states unequivocally that ornamentation is a crime. But he could only say that–he could only rid interiors of rugs, curtains and tapestries–because of the boilers and radiators chugging away in the background, resolving the problem of staying warm that humans have faced since time immemorial. In the same vein, the minimal white neutrality of the modernist style and its undeniable success to this day were only possible because the original and essential mission of decorative features was negated by the invention of central heating at the end of the 19th century, electric lighting in the first half of the 20th century, and air conditioning in the middle of the loth century. Central heating and electric lighting are so efficient that they’ve completely obscured the real, functional and practical value of interior decorations, which, in their various forms, served to improve thermal and light comfort (albeit inefficiently).
In the 21st century, if you’re cold, you simply turn up the radiator. No one thinks to put up tapestries or other wall hangings, or to go to bed wearing a night cap and toting a hot water bottle. In the last century, thanks to radiators, we moved beyond wall hangings, curtains, rugs and screens. Their insulating value has been forgotten, and they’ve become simple decorative, cultural and aesthetic signs.
In that sense, the defining slogan of modernity–Less is more–can be seen as a consequence of the widespread use of radiators. The modernists who came in the wake of Adolf Loos viewed their purifying task as a just struggle. Le Corbusier explained to his contemporaries on numerous occasions how decorating an interior was old-fashioned and lowered its use value: “Boudoirs decorated with black and gold pumpkin cushions are now just insufferable witnesses to a bygone spirit. We now prefer open space and bright light”.2 Continuing his diatribe, he adds: “Who needs such huge chandeliers? Who needs fireplaces? Who needs canopy curtains?”3
The phrase “Less is more” was attributed to German architect Ludwig Mies van der Rohe by American architect Philip Johnson, who curated the first major exhibition on modern architecture at the MoMA in New York in 1923. 4 But we can only do more with less–we can only have interiors that are smooth, empty and white rather than adorned with textiles and sectioned off by screens and curtains–thanks to boilers and radiators, which solved all the thermal problems that humans have cursed since prehistoric times. “I try to make my buildings neutral frames in which people and art can live their lives,” said Mies. This claim is somewhat naive, however, as he fails to note the role of fossil fuels in achieving his vision.
Plastics and brass
The use of today’s insulating materials suggests that the modern style has run its course, that we’re at the dawn of a new era in decorative art, and that a new look is emerging, one that we call the Anthropocene Style. Tapestries, curtains and rugs–in the form of insulation, vapour barriers and airtightness–are back in fashion. We can now look forward to enjoying their precision and elegance and discovering their full range of aesthetic possibilities.
In 2020, another material event alongside climate change may help to catalyse the transition to the Anthropocene Style. In the latter half of the 20th century, the materials used to adorn interiors gave owners a chance to express themselves, indulge their whims and play with the language of design through colours and materials laden with cultural or social meanings. But in April 2020, these choices took on a further dimension when researchers at Hamilton University in the United States published a paper on how long the coronavirus (SARS-CoV-2, previously called HCoV-19) could survive on various materials.5 They demonstrated that the virus lasted only eight hours on copper (unlike other metals), while it survived up to one day on cardboard and three days on plastic. This study offers some timely design lessons. Old doorknobs, doorbells and other brass fittings, for example, could help to slow the spread of infection. Going one step further, architects and interior designers may even start factoring health-related concerns into their choice of materials. The simple decision to switch from PVC or stainless steel doorknobs to brass ones could in fact mark the first step towards a broader paradigm change.
Interior designers, guided by both climate change and public-health concerns, are rethinking their aesthetic decisions. The result is a new form of decorative art for the 21st century–the Anthropocene Style.
LE CORBUSIER. Vers une architecture. Paris: Flammarion, 2008.↩︎
Ibid.↩︎
Philip JOHNSON. Mies van der Rohe. New York: Museum of Modern Art, 1947.↩︎
N. van DOREMALEN, T.BUSHMAKER, D. MORRIS et al. “Aerosol and Surface Stability of SARS-COV-2 as Compared with SARS-COV-1”. The New England Journal of Medicine, 16 April 2020, DOI: 10.1056/NEJMc200497.↩︎