The outdated British conservatorycould be part of a post-carbon thermal revolutionAround one in five homes in England has a conservatory, promising domestic bliss bathed in the sun. More light. More space. More living, reads the front cover of a recent catalogue of manufacturer Conservatory Land. Customers can choose between the Victorian, Edwardian or Orangery models, complete with injectionmoulded ridge details referencing those once cast in iron.The orangery, in its original form, was infact the precursor to the conservatory. Thesemasonry structures, with a predominantly glazed southfacing wall, emerged in 17thcentury central Europe to facilitate thebourgeoisies desire to cultivate citrus plants. They were often used to host guests and sited near, or appended to, living spaces, designed in the same material and language of their domestic host architecture. They largely predate greenhouses, which only began to proliferate in the early 18th century. These lighter weight, initially timber frame, buildings distanced themselves from domestic space as purposebuilt structures for the cultivation of plants.The conservatory has itsroots in the orangeries of Europe, providing the conditions for growing citrus fruits, as shown in this Dutch engraving from 1676. The contemporary British conservatory is far less exotic, epitomised in Martin Parrs photograph from 1988 (lead image)In the 18th and 19th centuries, the growing of exotic plants, sourced through colonial endeavours, proliferated; the botanist and designer John Claudius Loudon refined the design of a pinery, for the growing of pineapplesCredit:Wellcome CollectionIn the 19th century, glazed buildings ballooned in scale in Britain with the growing importation of nonnative plant species to the temperate northern European climate, intertwined with and driven by thecolonial project; this new glasshouse typology was conceived to simulate the plants original climate. The glasshouse became the architectural icon of the industrial revolution, used as the test bedfor fabrication techniques and heating technologies, creating ever larger and more thermally controlled spaces in iron and glass.The industry boomed towards the turn ofthe millennium, with conservatories ofteninstalled with little or no regard toorientationIn parallel, this period also saw the proliferation of glazed architecture at adomestic scale. John Claudius Loudon wasinterested in the technical, aesthetic and formal challenges posed by the integration of iron and glass structures into the classical language of Georgian domestic architecture. In 1825, he designed and built his own home on Porchester Terrace in London, identified by Stefan Koppelkamm inGlasshouses and Wintergardens of the Nineteenth Century (1981) as probably the first example ofadomestic conservatory. This early semidetached suburban dwelling was arranged around a domed conservatory on the front facade, looked onto and accessible from both homes. Lined with bedsfor thecultivation and display of plants, theconservatory was also designed to be frequented by the inhabitants and their guests. The dome was clad in glass scales and formed from curvilinear wroughtiron glazing bars that would go on to inform themuch larger structural systems of Joseph Paxtons Great Conservatory ontheChatsworth Estate in 1840 and theCrystal Palace for the 1851 Great Exhibition. Duringthe second half of the 19th century, conservatories became the musthave house extension for those without an estate on which to site a freestanding glasshouse. Companies such as Messenger &Co formed to serve this market, often producing the structures as well as the heating infrastructure for them.Conservatories dwindled in popularity during the interwar period; the intensive heating required to service these spaces suddenly seemed frivolous at a time of energy scarcity. Although early20thcentury modernists referenced the largescale iconic buildings of the 19th century, the domestic conservatory was largely forgotten. But withthe proliferation of highperformance, lowcost uPVC double glazing in the 1980s,the domestic conservatory made atriumphant return. Conservatories were rebranded as fully habitable rooms rather than spaces with a specific atmosphere inwhich to cohabit with plants. Technical advances and abundant cheap energy made domestic life in a glass room viable again. The conservatory became a costeffective house extension, developed to fall within householder permitted development an aspect of UK law that grants homeowners rights to extend and alter their home without submitting a formal planning application, subject to the development falling within certain parameters relating tosize, material and position.Loudon would go on todesign one of the first examples of a domestic conservatory as part of his own home, Porchester Terrace, in 1825The domed conservatory on the front of the home was shared by both halves of the early semidetached house. The Victorian conservatory was a space both for the cultivation ofplants and socialising, captured in this 1892 painting by Henry Edward John BrowneCredit:Russell-Cotes Art Gallery & Museum, BournemouthThe industry boomed towards the turn ofthe millennium, with conservatories ofteninstalled with little or no regard toorientation, many destined never to receive any direct sunlight. Conservatories are exempt from Part L, the section of the UK Building Regulations which defines thermal performance requirements. There are afewcaveats to this exemption, with conservatories needing to be heated onaseparate system to the rest of the house and requiring a door dividing them from themain dwelling. Conservatory advertising, however, would suggest otherwise, with illustrations showing kitchens, living rooms or openplan dining rooms in conservatories that often appear to be hooked up to the central heating. As a result of this misselling of the conservatory dream, these extensions are often poorly sited and lacking in sufficient devices for shading and ventilation. This has resulted in conservatories being largely viewed as poorly performing spaces and an energy drain too hot in summer and too cold in winter.Elsewhere in Europe, heating northfacing extensions of glass on suburban homes is farless common. A conservatory, more commonly styled as a winter garden in Europe, is instead seen as a passive solar device. This alternative understanding of the glazed extension is apparent today in the work of contemporary architecture offices such as Lacaton & Vassal, whose work builds on this tradition. Winter gardens have played a key role within Lacaton & Vassals oeuvre, from their early projects, which added offtheshelf agricultural greenhouses to single family homes more similar to the traditional suburban conservatory common in the UK through to their retrofit projects, which added stacked winter garden extensions to existing 1960s housing blocks.The glazed extension must be recontextualised as a solar device that has the potential to empower users to passively heat their homesAcross Lacaton & Vassals projects, the winter garden is never assigned a specific programme and is instead seen as an additional room onto which the programmed spaces of the home open. The winter gardens are conceived as a series of controllable layers external glazing, solar curtain, double glazing, thermal curtain expanding the thermal line of the building into a spatial device that can be opened and closed in reaction to the climate. The external glazing of the winter garden is purposely singleglazed or made from polycarbonate sheets, allowing high air infiltration and ensuring that the winter garden is not promoted as a heatable room. The postoccupancy analysis and environmental performance of their Cit du Grand Parc project in Bordeaux, designed with Frdric Druot and documented in their recent publication Its Nice Today: On Climate, Comfort and Pleasure, suggests that the renovation has reduced the energy use ofthebuilding nine times, three times moreeffective than what would have been achieved within a standard renovation without winter gardens.Though less common, winter gardens appended to apartments have a precedent inthe UK. Housing designed by ZEDfactory in the early 2000s, including BedZED (ARNovember 2003 and AR April 2023), often incorporated winter gardens designed to passively heat the adjacent spaces. Morerecently, Henley Halebrowns KingsCrescent Estate redevelopment for HackneyCouncil, completed in 2017, added southfacing winter gardens to existing housing blocks. Echoing the intentions ofthe Lacaton & Vassal projects, the renovation illustrates the relevance ofglazedextensions within the context ofclimate reliance and improving existing living standards.Loughboroughbased company Messenger & Co produced all the components for sometimes very elaborate conservatories, such as this one from 1880Credit:RIBA CollectionsMore than 200 years later, conservatories can still be ordered off-the-shelf, like this model from DIY shop B&QCredit:Justin Kase Z12Z / AlamyCapturing the thermal potential ofconservatories in singlefamily homes islesswidely explored but not a completely foreign concept within the UK. Simos Yannass 1994 publication Solar Energy andHousing Design includes analysis of several British late20thcentury examples of passive solar conservatories, such as theFuture Home 2000, part of Milton Keynes HomeWorld 81 expo, which incorporated asouthfacing glazed atrium todecrease theenergy load ofthe home.Research I undertook as part of the Design Museums design researcher in residence programme, with Atmos Lab (theenvironmental designers who have collaborated with Lacaton & Vassal since 2018) sought to rediscover the solar potential of the suburban conservatory extension. Thermodynamic analysis of our case study design proved that an adaptable and wellsited solarheated conservatory could reduce the annual energy load required to heat adjacent spaces by approximately half, while adding space andimproving natural light and ventilation. With around 20 per cent of UK households in fuel poverty and the urgent need to decarbonise our existing housing stock, theconservatory could form part of holistic retrofit strategies that not only improve thermal efficiency but also living standards.Asouthfacing conservatory helped topassively heat the Future Home 2000, built as part of Milton Keynes HomeWorld 81 exhibition. The expo included 36 show homesthat explored energyconservationCredit:Heritage Image Partnership Ltd / AlamyMore recently, Henley Halebrown added two-storey winter gardensto an existing postwar block at Kings Crescent Estate in Stoke Newington, as part of anestate regeneration scheme in 2017Credit:Jim StephensonHowever, attitudes towards control over the climate remain a critical challenge within the current paradigm. Expectations of the constant usability of conservatory extensions can be traced back to the 19thcentury glasshouses promise of constructing an artificial environment through the use of technology and abundant energy resources. Promoting more nuanced requirements for adaptability, orientation and flexible inhabitation make for a harder sell, but if the conservatory is to make a comeback, then it will need to be reimagined as part of integrated environmental strategies rather than a nostalgic interpretation of a 19thcentury ideal.The conservatory, orwinter garden, hasamore illustrious reputation elsewhere in Europe, in particular in the work of Lacaton &Vassal. Large winter gardens, enclosed inpolycarbonate, characterise the housing which they designed for older people in Rixheim in 2021Credit:Philippe RuaultAdjustment to the expectations around usability must also come hand in hand with the provision of generous space standards that allow for expansion and contraction through the seasons. It is criticalthat theconservatory is not given anassigned programme of the conventional family home. Instead, the glazed extension must be recontextualised as a solar device that has the potential to empower users to passively heat their homes. Through the thermal delight of sitting in the sun, the conservatory could be well placed to encourage a more dynamic relationship with the exterior environment and an openness toestablish broader definitions of thermal comfort above 21C and below 18C. The conservatory must therefore be considered as an additional space that the thermally controlled programmed spaces of the home can open onto, but can also retreat from, enriching rather than compromising space standards. In the reorientation of the conservatory extension towards the sun comes an opportunity to combine the tradition of home improvement with an increase in the resilience of our existing housing stock to adapt to the changing climate. More space, more light, more living, forever.2025-02-13Owen HatherleyShare AR February 2025ExtensionsBuy Now