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Last edited 14 Jun 2022
Hydroponics and buildings
Hydroponics originates from the ancient Greek "hydros," meaning water, and "ponos," meaning work. It is an agricultural practice that uses no soil, but instead plants are grown in aerated water pools. Whilst it is an ancient practice it was more formally named and gained traction around the 17th century. In the last decades it has seen increased interest because of its reduced use of water, the possibility to grow more in less space and the ability to better control the growing environment against pests. More often than not hydroponic farms are located in closed spaces or specially dedicated green houses, with oxgeninated water pools. Increasingly hydroponics are being seen with the potential to become architectural features of buildings representing a greening of urban areas and the market for home micro-aquaponic systems is also expanding.
Hydroponics has most likely been practised for many years with evidence of it being practised by the Aztecs in Mexico, who, being denied land, were forced to settle near lake Tenochtitlan, where they most likely grew food through floating hydroponic systems. It is thought the hanging gardens of Babylon also used a form hydroponics to grow plants high up in towers, whilst ancient Egyptian hieroglyphics describe the growing of plants in water along the Nile without any soil. Finally indications are that the Roman Emperor Tiberius grew the cucumbers which he craved out of season via water culture.
The relationship between plants and water was studied in the 1600's by the scientist Francis Bacon who first published a work on the topic. In the 1700's John Woodward continued to study plant growth in different soil solutions, and towards the end of the century and early 1800's Joseph Priestley discovered that plants absorb carbon dioxide and release oxygen. Ingen-Housz established that these processes worked more quickly in bright light, and Nicolas De Saussure proposed plants as being composed of mineral and chemical elements obtained from water, soil and air, and listed nine elements believed to be essential to plant growth. Towards the end of the century many scientists showed the potential to grow plants in inert minerals with various water solutions, with von Sachs, and Knop finally doing so in only a water solution.
This lead to what was considered nutriculture, where plants could be grown in a water solution containing salts of nitrogen (N), phosphorus (P), sulphur (S), potassium (K), calcium (Ca), and magnesium (Mg), now defined as the macro-elements or macro-nutrients. Later these were extended to micro or trace elements, of iron (Fe), chlorine (Cl), manganese (Mn), boron (B), zinc (Zn), copper (Cu), and molybdenum (Mo) which were required in smaller amounts. In the 1900s these laboratory techniques known as nutriculture, chemiculture, and aquiculture gained the interest of crop developers for larger production. Dr. William F. Gericke of the University of California extended his laboratory experiments to practical crops for large scale commercial applications and in doing so referred to these nutriculture crop systems as hydroponics. He grew vegetables hydroponically, including beets, radishes, carrots, potatoes, and cereal crops, fruits, ornamentals, flowers and tomatoes.
Today there are various systems which are accepted as being hydroponic, or growing without soil. The soil is replaced by growing mediums or in some cases more directly by a water solution, some of the mediums used today are:
- Rockwool / stonewool
- Clay pellets
- Peat moss
- and in some cases water (see below)
Ebb and flow systems (also called flood and drain) use a medium which does not provide nutrients but gives root stability, such as perlite. Nearby is a reservoir with the water and mineral solution. The solution is pumped over the roots periodically and then left to drain, so the roots spend time both in and out of water, the air providing the oxygen needed. This systems work best with smaller plants and set-ups like home herb growing.
Drip systems are very similar to ebb and flow, with the water being pumped through smaller tubes that drain above the plants. It is suitable for plants that have a less developed root system - also at a smaller scale.
Wick systems are again similar to ebb and flow because a growing medium is used, but it uses capillary action and thus does not require any pumps. Plants are placed into a tray filled with a medium like perlite or rockwool, strings then hang from this into a tray of solution below. Acting as a wick the strings soak up the medium and constantly feeds the plant.
 Nutrient film technique (NFT)
Nutrient film technique (NFT) does not require a medium as roots are suspended above a flowing water solution. This is popular with larger-scale systems where roots are established because pipes can be stacked, so provide a greater harvest in a smaller space and it is relatively simple to maintain. The pipes or channels are set to fall, the solution is aerated either through a simple water fall or using an aerator and then recirculated with a pump.
In 2000, 40% of food in the UK was imported, and self-sufficiency in the following years reduced with imports increasing. In 2008 the Department for Environment reported 95% of our fruit and 50% of vegetables as being imported. By 2020 46% of total food consumed in the UK was imported. Agriculture is relatively energy intensive, thus food prices are effected by global markets and oil, as the demand for bio-fuels increases so does the competition for fertile land leaving some levels of vulnerability (EC 2008).
In 2022 the UN reported that because of the war in Ukraine, as a major exporter of maize and wheat, global food prices were likely to increase by up to 20%, which would likely hit the poorest hardest. During the period of COVID-19 when much commercial activity was shrinking, the hydroponics market expanded and is predicted to increase globally by 10% or more over the coming years.
The increasing impacts of climate change on growing seasons and the pressures of carbon reduction have made commercial but localised hydroponic plants increasingly viable. The carbon footprint of food sourced from around the world is significant, with part of this due to transportation emissions. Crops grown hydroponically, can be grown in greater density and over shorter periods, significantly increasing harvest rates. Production is less weather dependant - for example quality rejection for tomatoes grown hydroponically of just 2% compared to nearly 50% for field grown (Thanet Earth n.d.).
No pesticides are needed, as no bacteria are present in the growing environment as there is no soil. Minimal water and fertiliser are used as only the bare minimum is provided to meet the plant needs. This is unlike soil production were there are significant losses through run off, and as much as 90% of soluble nutrients can be leached from the soil, which can also result in localised environmental issues.
In 2010 Thanet Earth was revealed as the largest hydroponic greenhouse in Britain - an £80 million project covering 220 acres of Kent farmland to provide a British food source year round. Meanwhile the number of micro or localised hydroponic farms in the UK has increased and the home hydroponics industry is expected to have a yearly commercial growth rate of 20%.
Hydroponics has the potential to benefit the country and environment. While expensive to build, this factory like system provides an alternative product that can be grown locally, that is fresh, pesticide free, environmentally friendly and at the same time supports the local economy and allows us to be in control of our future.
 Hydroponics and buildings
The integration of plants, trees and farming into buildings stems back to the hanging gardens of Babylon or before but the extent to which this and others were hydroponic is debatable. Though through time the growth of separated botanical buildings called orangeries or conservatories, were reserved ( at least in th UK ) for only for the very wealthy, due window and glass taxes of the 1700's.
By the 1800's often driven by the new found desire and status of growing exotic fruits such as pineapples, those who could afford it built glass roofed conservatories to achieve this. It was not until the middle of the century that the much hated window tax was repealed, largely due to a national campaign against it which was supported by impacts of health on building occupants. The very same year that the tax was finally repealed the great exhibition of 1851 revealed one of the most celebrated of glasshouses; Crystal Palace.
This trend for public glass pavilions continued but by the beginning of the 1900's with no taxes and a reduction in the cost of glass production due to industrialisation, more people could afford their own glass houses - or more commonly known greenhouses. The Land Settlement Facilities Act of 1919 established to assist returning service people to resettle, was then extended to the labouring poor and finally the Allottments Acts meant people could also have access to land, which was available in the form of statutory allotments that local authorities could not sell off or covert without Ministerial consent.
Whilst the modernist movement in architecture is perhaps not known for its integration of planting and greenery into buildings, due to its industrial aesthetic, by the 30's certain modernist Architects such as Alvar Aalto became known for incorporating humanist aesthics, greenery and nature. Around this time hydroponics itself (referred to as nutriculture, chemiculture, and aquiculture) started taking steps out of the lab and into the commercial world of farming.
One of the earliest built and functioning hydroponic installations was on Wake Island in the Pacific Ocean. It was built by necessity in the 1930's as there was no soil, freight was costly and it was used as a refuelling stop for Pan Am flights at the time. It is also known as the Pan Am Wake Island Hydroponicum. It was a series of open beds and greenhouses successfully used grow vegetables for the passengers and inhabitants. In the 40's the US army used a similar principle to grow food for the troops in gravel on the barren Ponape island in the West Pacific.
By the 60's and 70's marijuana growers had realised the benefits of hydroponics and started to develop their own systems, with the NFT method being invented around this time and the largest supplier of chemical nutrients, General Hydroponics being born. At around this time the term biophillia was also coined developing a field that was focussing on an approach to architecture that connects buildings and occupants more closely to nature, incorporating natural light, ventilation and planting for healthier internal environments. It was also a growth period for community gardening.
In the 80's Walt Disney World opened the Experimental Prototype Community of Tomorrow (EPCOT) Center which featured a variety of hydroponic techniques. In terms of space exploration NASA's interest in hydroponics as part of its Controlled Ecological Life Support System (CELSS) has seen hydroponics solutions increasingly incorporated into space architecture.
By the end of the 90's further terms were being used to describe the urban garden or gardening in constricted spaces such as vertical farming which promised increased yields on 10% of the land, which has helped a continual and gradual growth of commercial farming to this day.
- Landscape design.
- Living facade.
- Rain garden.
- Rainwater harvesting.
 External references
- Department for Environment, Food and Rural Affairs. Ensuring the UK's Food Security in a Changing World . July 2008. http://www.ifr.ac.uk/waste/Reports/DEFRA-Ensuring-UK-Food-Security-in-a-changing-world-170708.pdf.
- EC. Causes of the 2007-2008 global food crisis identified. Jan 20, 2008.
- Thanet Earth. http://www.thanetearth.com.
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