Some of mankind’s earliest attempts to understand climate came from observing simple natural phenomena such as slope aspect. The slope on the left faces north and supports a different type of vegetation from the slope on the right which faces south and is drier.

It didn’t take long in the history of civilisation to figure out that tall plants like olive trees are best grown on south facing slopes as they receive more light. Planting them in north-south rows meant less mutual shading.

Low plants such as grape vines were best planted on south-facing slopes in rows running east-west. Grape vines produce more sugar in proportion to the sunlight they receive – a fact exploited by winemakers since about the 2nd century.

Grape vines are also an example of espalier which is the practice of training fruit trees to grow in only two dimensions such as this. It’s another way of getting more light to the fruit.

The next step in the evolution of this knowledge was the fruit wall. Not this fruitwall®!

A fruit wall is when espalier happens against a wall. The wall provides support and, if it faces south, reflects light back to the plant whilst its thermal mass absorbs and then emits heat that extends the growing season of the plant.

This now brings us to oranges! We think the orange was first cultivated in China around 2500 BC but, sometime in the 16th century, Portuguese merchants introduced the sweet orange to the Mediterranean countries.

The word entered Late Middle English in the fourteenth century via Old French orenge (in the phrase pomme d’orenge). The French word, in turn, comes from Old Provençal auranja, based on Arabic nāranj. In several languages, the initial n present in earlier forms of the word dropped off because it may have been mistaken as part of an indefinite article ending in an n sound—in French, for example, une norenge may have been heard as une orange. The sweet orange quickly was adopted as an edible fruit. It also was considered a luxury item and wealthy people grew oranges in private conservatories, called orangeries. By 1646, the sweet orange was well known throughout Europe.

Orangeries wouldn’t have been possible without the development of glass.

The orangery originated from the Renaissance gardens of Italy, when glass-making technology enabled sufficient expanses of clear glass to be produced. In the north, the Dutch led the way in developing expanses of window glass in orangeries.

Their elevated internal temperatures of orangeries were the result of what we now know as solar gain, and the sun hitting the thermal mass of the floor. Wealthy people were delighted to have a new function to add to already oversized houses but, although orangeries started off as showing off your oranges and that you were wealthy enough to grow them, they soon became full-time places for banqueting and showing off in general.

The orangery, however, was not just a greenhouse but a symbol of prestige and wealth and a feature of gardens, in the same way as a summerhouse, folly or “Grecian temple”. Owners would conduct their guests there on tours of the garden to admire not only the fruits within but the architecture without. Often the orangery would contain fountains, grottos, and an area in which to entertain in inclement weather.

This orangery in Kuskovo circa 1760 was never used for orange trees even though its sloping walls – a Dutch innovation – allow more light than regular glazing. The Russian for orange, btw, is apelsin (апельсин).

Even today, it is a common Russian courtesy to offer guests an orange – or so we were told in 2008 when Foster & Partners were hyping this project that was quickly dubbed “Project Orange”. Check out the model. The project gets no mention on the F&P website. All that remains is a bit of internet debris on e-architect.

2008 Project Orange, Moscow, Russia Feasibility Study The 80,000 sqm scheme for a contemporary art museum with commercial elements and housing is for development firm Inteco. The project is influenced by natural structures including that of the orange, a historic symbol of opulence in Russia. The circular plan, with five segments rising to 15 storeys, is designed to protect against the cold winter climate while allowing light deep into the building through glazed slots in the elevation.

I remember reading somewhere that this is what Foster & Partners are good at – dressing up high-tech PoMo whimsy with eco-justifications. I’ve never forgotten it. Technically speaking, an orangery is a greenhouse attached to a house. It’s heated by solar gain only. They enabled orange trees to be cultivated in locations where they’d otherwise not survive the winter frosts. Even today, gardeners will uproot their geraniums (an import from South Africa) and store them in a greenhouse for replanting in spring. Click here for tips on how to over-winter your geraniums.

Hothouses are greenhouses that are artificially heated to create an internal environmentthat enables the cultivation and appreciation of exotic plants that would otherwise not survive whatever the season. The Orangery at Schöenbrunn Palace is a hothouse as it was heated by a hypocaust system. That’s underfloor heating such as used by the Romans. Here’s the principle.

This orangery was used for overwintering orange trees but a fair share of entertaining took place as well.

For as long as the time of the Habsburgs the Orangery was a place of musical and artistic festivities. During one of these events, Wolfgang Amadeus Mozart and Antonio Salieri competed in a musical contest at court – a contest still considered unique in music history.

The advent of steam boilers coupled with the Victorian passion for colonialism and the attendant bounties/curios it brings, led to a boom in botany as well as hothouses, even though they usually came to be called conservatories. A conservatory is a basically a sunroom with decorative plants to create or enhance the illusion of being outside. This is a conservatory.

If a greenhouse is specially heated for the sake of the plants it contains, then it is a hothouse. If a greenhouse is heated for the sake of its human users, then it is a conservatory – a substantially glazed room that may or may not contain plants exotic. Even though one of the first uses of skylights was Burlington Arcade in 1719, it was at least another hundred years before glass skylights became a standard feature of orangeries, hothouses and conservatories. These days, we think of a hothouse as where vegetables – especially tomatoes – are grown for profit. Flowers too.

These days, an orangery is probably where someone you know will have their wedding reception.

Or ceremony.

And these days, a conservatory is what your suburban neighbour is requesting planning permission for. It probably looks like this – an addition, substantially glazed, aesthetically external to the “main composition” yet attached to it on one side, preferably south. The parapet wall and internal gutter are residual stylistic affectations.

Inside, your neighbour’s conservatory will probably look like this – some extra living space with a bit more glazing than usual.

It was never going to end well for orangeries. What began as an exercise in reducing food miles by providing oranges with conditions for their growth ended with people wanting that warmth and light for themselves.

The demise of the orangery was played out many times but the “orangery” Thomas Jefferson had built at Monticello was a precursor for them all, going from functioning greenhouse to family sitting room over the twenty years from 1807–1827.

Jefferson, like many gentlemen of the time, was an amateur botanist and people around the world shipped him specimens.

Whether or not these strange species from a distant land thrived or were even planted remains a mystery. As with a multitude of plants Jefferson received from his friends throughout his life, he did not record their fate. What Jefferson did record made the prospect of maintaining any sort of tender plant doubtful. His weather observations from January 1810 noted his bedroom temperature at 37 degrees Fahrenheit and the greenhouse at 21 degrees. In April 1811, a year before the Cape bulbs arrived, he wrote to McMahon [the man sending Jefferson plants from South Africa]:
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“You enquire whether I have a hot house, greenhouse, or to what extent I pay attention to these things. I have only a green house and have used that only for a very few articles. My frequent and long absences at a distant possession render my efforts even for the few greenhouse plants I aim at abortive. During my last absence in the winter, every plant I had in it perished.”
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Jefferson’s admission to McMahon himself of this inhospitable environment suggests that perhaps McMahon was encouraging Jefferson to make an effort to provide some heat. In any case, by 1816 most references to plants for the “green house department” were in the distant past. Jefferson’s South Piazza was serving more as a storage space and utilitarian room where he kept his large rectangular work bench and chest of tools that he had acquired in London. 
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Correspondence between Jefferson’s granddaughters in later years indicated that plants were actually removed from the frigid greenhouse during winter months. Cornelia Randolph wrote to her sister Virginia on December 1, 1820, “I had all our plants moved into the dining room before I left home and yours along with them. I hope they may be able to bear this bitter cold weather.” Again, on October 31, 1825, Cornelia would write, this time to her sister Ellen, “Mary and myself are established in mama’s room with all her furniture and the sunny window in which I shall range my green house plants when the weather is cold enough to take them in . . .”
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By the end of his life, Jefferson’s greenhouse appears to have functioned more as an enclosed porch, Seven months after his death, Mary Jefferson Randolph wrote to Nicholas Trist that “the green house had been used so long as a common sitting room for the whole family that there were many of our things in it and in packing up some may have escaped our observation.” The following year she described again the transformation of the greenhouse space in a letter to Ellen Randolph Coolidge: “How often I wish I could see your two sweet babies, added to the four that now run about the house or roll and tumble on the floor in the green house, which serves as a very pleasant little sitting room for us, during part of the day (when the sun does not shine upon the windows) and is at all times a favourite play place for the children.”

The question then is, why didn’t he just build a house with a space like that to start with? And why doesn’t everybody else? True, at 21°F (-6.1°C) in January, it probably wasn’t a favourite place to play, but it seems like it wasn’t such a bad place to be otherwise. You don’t have to be an orange to appreciate some sunlight and warmth during the day. This then brings us back to Lacaton & Vassal’s Lapatie House.

When it gets too cold for sitting you can withdraw and let your orange trees winter there .

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