Biomimicry in Architecture by Pawlyn Michael;

Biomimicry in Architecture by Pawlyn Michael;

Author:Pawlyn, Michael;
Language: eng
Format: epub
Publisher: RIBA Publications
Published: 2016-02-24T16:00:00+00:00


One particularly inventive approach to keeping buildings cool using radiation loss has been devised by engineer Salmaan Craig using a powerful problem-solving methodology known as BioTRIZ. The forerunner of this technique was TRIZ (a Russian acronym for ‘Theory of Inventive Problem Solving’) developed by Genrich Altshuller (1926–98). Any problem can be defined in terms of ‘I want A, but it is prevented by B’, which is similar to the German philosopher Hegel’s concept of thesis, antithesis and synthesis. The resolution, in Hegel’s terms, was something that managed to combine thesis and antithesis. Altshuller analysed thousands of patents and distilled from these 40 inventive principles, each of which has the potential to be a synthesis (in Hegel’s terms). Julian Vincent and his colleagues, Drs Olga and Nikolay Bogatyrev, extended Altshuller’s work by studying roughly 2,500 examples of how problems are solved in biology and producing a refined matrix of inventive principles based on their conclusions.149 The thesis/antithesis defined by Salmaan Craig was a roof that was insulated against the sun but that allowed infra-red heat to radiate at night. Whereas conventional technology would often have pointed towards manipulating energy in some way (such as air-conditioning) to solve the problem, BioTRIZ indicated that the synthesis found in biology would most commonly involve modifications to structure. This led to a method of structuring a layer of insulation on top of a concrete roof that blocked most of the sunlight while funnelling the long-wave radiation using reflectors towards transparent apertures (fig. 116). Test panels demonstrated that the roof temperature could drop as much as 13 °C below ambient by entirely passive means. The concrete would act as a heat store so that it would radiate this coolness to the rooms below during the day. Craig estimates that the biomimetic roof would maintain the concrete at an average of 4.5 °C cooler than a standard roof in Riyadh, Saudi Arabia.

Evaporation is an extremely effective means of cooling because water’s specific heat capacity is relatively high and therefore large amounts of heat can be dissipated with small amounts of water. The microscopic pores (stomata) on plant leaves control the rate of evaporation and the exchange of gases involved in photosynthesis. When temperatures increase, the stomata open wider, which causes more water to evaporate and allows the plant to stay cooler than its surroundings. In extreme cases the leaves wilt, which has the effect of reducing the amount of leaf surface presented to the sun. The water in plants is transported through vascular bundles, driven by osmotic pressure from the roots pushing the water up, transpiration loss from the leaves pulling the water up and, to a lesser degree, capillary action, which relies on edge contact at a free surface to provide the force.

Tate Harmer Architects explored the potential of using transpiration in their IHub competition scheme (fig. 117). The aim was to create a building that cools itself using water but without pumps. If capillary action and an equivalent of transpiration pull could be harnessed to deliver the water, then the rate of evaporation would drive the process.



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