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by: Akanksha Rathee Elena Mitrofanova Pongtida Santayanon

01 Material properties 02 Expansive deformation 03 Main concept 04 Breathing system 05 Hydroceramic

The increasing development and application of “smart” materials in other industries has opened up new design possibilities at the material and “behavioral” scale of architecture. Smart materials react to external stimuli such as stress, temperature, moisture, pH and electromagnetic fields by changing their physical and chemical properties. These responses to external stimuli can allow for buildings to imitate life processes and enhance their performance. The studio [DMIC] DIGITAL MATTER INTELLIGENT CONSTRUCTIONS in the academic year 2014 at the Institute of Advanced Architecture of Catalunya aims to redefine and embed intelligence“ into the built environment by the use of responsive materials, designing and implementing systems to aid the building performance by digital simulations and fabrication. The built environment then becomes a living thing as part of nature and not outside of it. We can start defining biological systems as metabolisms that are live processes between the building as an organism and its surroundings. One that reacts with the ecosystem in the form of feedback : learns from its surroundings and gives back. By the precise control of inputs for smart materials a series of properties (mechanical, electrical, optical, magnetic etc.) are exhibited which can be manifested into functionalities like self repairing, shape


change, decontamination and transformation of energy. This project aims to speculate the thermodynamic processes in a building and how these can be tackled passively with a class of materials called „hydrogel“. The term „hydrogel“ refers to a class of substances that absorb and retain a large amount of water. Chemically they can be insoluble polymers of hydroxyethyl acrylate, acrylamide, polyethylene oxide, and others. As a cooling aid they work by exposing the absorbed water to a large surface area. Since the heat of vaporization of water is about 0.6 kilocalories per gram, a cooling effect occurs. Taking this phenomenon as a hypothesis, the project aims at prototyping a custom building element by the hygothermal (humidity and temperature) analysis of buildings to meet the habitable conditions required for the comfort zone in a particular context.



material properties Super Absorbent Polymers (also called Superabsorbent Polymer and �SAP�) are a class of cross-linked, non-biodegradable polymers capable of absorbing and retaining up to 500 times their weight in water. It is an ecologically friendly (nontoxic) material. It is also inexpensive and easilly available comercially. 100 spheres of hydrogel cost 50 cents. Applications: Industrial (flood control, floral decoration, packaging & transportation, industrial waste management); Agriculture, horticulture & landscaping; Gel wound dressing, diapers and napkins, fake ice & artificial snow, underground cable water proofing, etc.



Sodium polyacrylate belongs to a family of water loving or hydrophilic polymers. It is a powder which takes the form of a coiled chain. There are two important groups inside its polymer chain - carbonyl (COOH) and sodium (Na). They are responsible for the overall absorption potential of the polymer. When the polymer is in the presence of a liquid, the sodium dissociates from the carbonyl group creating two ions, carboxyl (COO-) and sodium (Na+). The carboxyl groups then begin to repel each other because they have the same negative charge. As a result of the repulsion between the like charges, the sodium polyacrylate chain uncoils or swells and forms a gel substance. The action of swelling allows more liquid to associate with the polymer chain. There are four major contributors to sodium polyacrylate’s ability to absorb liquids or swell. These contributors are hydrophilic chains, charge repulsion, osmosis and cross-links between chains. Ions in the polymer chain such as carboxyl groups (COO-) and sodium (Na+) attract water molecules, thus making the polymer hydrophilic. Charge repulsion between


carboxyl groups allow the polymer to uncoil and interact with more water molecules. Cross links between the polymer chains prevent polymer from dissolving in water and other liquids. When the chains become hydrated, the cross links prevent them from moving around randomly. This decrease in random movement or entropy producess a stiff gel. The number of cross links in polymer affects the amount of absorption for the polymer as well as the strength for the gel. For example, the more cross links in the chain, the less able the polymer is to absorb liquids and the stronger the produced gel.


The first exploration was to see hydrogel’s behavoir in water. We made this test with super absorbent powder that is used in hygiene products. We added 50 ml water to 1 ml of the material and it became gel in 30 seconds.

polymer crystal 1 ml

adding water 50 ml

After adding 50 more to the gel in 20 seconds the gel becomes 120 ml. Adding 50 ml more of water the gel in 30 seconds gel becomes 190 ml. hydrogel 51 ml

adding water +50 ml

20 seconds - hydrogel 120 ml

adding water +50 ml


30 seconds - hydrogel 190 ml //layer of water visible


SAP in crystals (solid spheres). We were using three different sizes powder, crystals and spheres. The powder crystals are <1mm in size, the crystals are about 7mm in size and the spheres are 20 mm in size. These polymers have the capacity to increase 800 times in volume when put in water.

SAP in powder.

2.5 hours

TEST 1: We tested the time and levels of absorption possible in the three different kinds of hydrogel.

20 ml water to 4ml powder

4 seconds

SAP in gel.

To see if fully-absorbed hydrogel (the one that has stayed in form of gel for a long time) can still absorb more water if more time is given.

hydrogel 50 ml



adding water 50 ml

pieces are floating in the water, not absorbing more of liquid


TEST 2: We put super absorbent powder in a tube to check if it can transmit water through itâ&#x20AC;&#x2122;s volume. We started to drop water from the top of the tube and SAP absorbed water untill it reached 50 mm from the upper line. Then the diffusion inside the material stopped. Conclusion : The greater surface area of exposure to water the faster the absorption.

2 ml of SAP powder in the tube + 10 ml of water from the top //started to absorb until reached 5 cm, then the diffusion of water in a tube with SAP

TEST 3: Second test is to see how we can dry the hydrogel. We put 50 ml of the substance in the microwave and it became smaller in 7 minutes. Which is considerablly smaller than the amount of time it take to evaporate naturally (without the need of external energy). Conclusion: More heat in the surrounding of tthe gel accelerates the evaporation process.


hydrogel 50 ml

microwave 750 watts

7 minutes -gel pieces look smaller and scattered

we gather the pieces, there are crystal and gel


If hydrogel can absorb water back and can be air-dried again.

hydrogel 50 ml

approximately 1.5 cm in size

after microwave 16 minutes

crystals are smaller in size

Test 4 :With hydrogel in crystlals we wanted to see the difference when it is air-dried either dried in a microwave. For air drying it took 2 days for 150 ml of fully absorbed hydrogel. And in microwave it took 16 minutes, the crystals became smaller in size than air-dried ones. The second test shows that dried in a microwave hydrogel can absorb water again. It absorbed 25 ml of water in 45 min and the rest (25 ml) over night.

If dried hydrogel can absorb water back in again.

dried large hydrogel 1 ml // tap water 50 ml mix and leave it for 15 minutes

45 minute


over night - fully absorbed gel


If hydrogel can absorb water back and can be air-dried again.

dried hydrogel 2 ml

tap water 50 ml (absorbed)

air-dry for 20 minutes

the gel turned into crystal again

TEST 5: Reversible reaction : This test shows the reversible process in SAP. To check this we put 50 ml of water to the 2 ml of dried hydrogel (in powder). After it absorbed the liquid we air-dried with the heater and the gel turned into the crystal again. Test 6 : Reaction with alcohol. Second test is to check how crystals react with alcohol. In the mixture of 1 ml of SAP and 50 ml of alcohol after 15 minutes some of the crystals absorbed water but not completely.

How polymer crystal reacts when alcohol is added.

polymer crystal 1 ml


alcohol 50 ml

mix and leave it for 15 minutes

the crystal absorbed the alcohol but it looks very dry in comparison to the one with water


Test 7 : We made an experiment with the acid. After 1 hour the hydrogel became curdled instead of absorbed. So that acid solution can be separated from SAP. The internal structure is ruined.

hydrogel 25 ml lemon juice 25 ml mix without stirring

the gel became curdled instead of absorbed


we can separate the liquid out easily


hydrogel 25 ml in crystals Test 8 : As more salt is added to the hydrogel, the positive sodium ions (Na+) replaces water (H2O) and leaves less space for the water molecules. Negative charges along the chain repel each other less in the presence of the sodium ions and so the chains become morecoiled up. This also squeezes out water from the hydrogel. (a small change in salt concentration can have a significant effect on the amount of water leaving the hydrogel.)

gel pieces become smaller after 2 min

layers formed, water is released

large hydrogel 25 ml


left overnight


salt 5 ml mix and stir

salt 5 ml

gel pieces floating in the water


expansive deformation

In this phase of exploration we were searching for forms and geometries in prototypes that would respond to the volume expansion property of Super Absorbent Polymers.



This prototype is combining the material expansion property with a linear geometry to see wether the expansive property of the material can cause the foam to bend.

The same test was repeated with different type of crystals (artificial snow, small crystal and spherical crystal).

This prototype is to control the way the crystal grows. The fabric allows the water to pass and the folding geometry acts as container.

fist minute

one hour

spherical crystals were contained in each compartment of the prototype

artificial snow


hydrogel in spheres

water was injected to only one side of the prototype


The chain of reversed units can cause curvature in the direction and folding in the other when the water is input on one side.

Elastic textile pockets filled with hydrogel swells with the intake of water.. The layer with threads allow to divide pockets from

each other so that they grow stepwise.

fabrication process



The prototype presents a combined material system. The first layer is an absorbent fabric that is sewn with equal patches, the second is a stretchable textile. Layers are sewn with each other creating pockets for hydrogel. Each section contains 7 - 10 Super Absor-


bent Polymer crystals. When it is dryed, the form is flattened and 2-dimentional. After absorbing the water the structure forms aspherical shape because of the different streching properties of the two layers.

absorbing 150 ml of water in 2.5 hours.


main concept

CONCLUSIONS 1. Expansive property of hydrogel to create movement is not ideal and against the material behaviour. 2. Expansion strength of hydrogel is really low under pressure. 3. The material should be used to set up an architectural proposal for cooling.



Self-organisation is a process through which the internal organisation of the system adapts to the environment to promote a specific function without being controlled from outside. Biological systems have adapted and evolved over several billion years into efficient configurations, which are symbiotic with the environment. Form, structure, geometry, material, and behaviour are factors, which cannot be separated from one another. The premise of this research is to integrate cooling and actuation functions into a hydrogel composite material system. Staying cool is critically linked to staying hydrated. Yet the costs of air conditioning in our homes and offices, equipment and installation, maintenance, and large amounts of electricity are overwhelming. Here are some of nature’s strategies for staying cool when it gets hot. Plants and animals have a diversity of ways to keep cool. Some are well-known, like sweating. Others may be less familiar, such as how ticks pull water from the air. Honeybee colonies collect water for cooling of the brood area by evaporation on hot days (Lindauer, 1955; Seeley, 1995). Water is collected by water foragers, then distributed around the hive and in cells containing eggs and larvae; fanning


accelerates its evaporation, as does regurgitation and evaporation on the tongue (Lindauer, 1955). The sweat glands of many mammals aid thermoregulation through evaporative cooling. “Sweat glands play an extremely important part in temperature control. Shaped like a tube, knotted at the bottom and opening out of the epidermis at a ‘pore’, sweat glands secrete a colourless liquid which evaporates on the surface of the skin removing excess heat.“ (Foy and Oxford Scientific Films 1982:79) The rounded shape of the leaves of pebble plants minimizes evaporation due to its low surface area relative to volume. “Pebble plants grow in the stonier patches of the same Namib Desert. They survive by living partly underground. Their leaves have been reduced to a single pair, fat, round and succulent. Such a rounded shape, with a very low surface area for a given volume, reduces evaporation to a minimum and is therefore a great help to the plant in conserving its water in the intense heat.” (Attenborough 1995:265)


Typical evaporative cooling.

Hydro Panel cooling system.

Energy is required to change water from liquid to vapour. This energy is obtained in an adiabatic process from the air itself. Air entering an evaporative air cooler gives up heat energy to evaporate water.

Evaporative air conditioning uses evaporation to cool the air. In an evaporative cooler, such as Breezair, a pump circulates water from the reservoir on to a cooling pad, which in turn becomes very wet. A fan draws air from outside the unit through the moistened pad. As it passes through the pad the air is cooled by evaporation. Hydro Panel Cooling System



Advanteges: 1. Good in structural behavior due to rigid geometry of a sphere. 2. Strong type of hydrogel (because of the amount of cross links) 3. Slow water discharge rate least surface area compare to other shape measurable in terms of volume



Thinking about architectural application we created hydropanels. Inside we placed hydrogel and capped the panel from both sides to hold it. The exterior side has perforations to collect the rain water to feed the polymer.



For the interior part we tried 3 types of materials with different porosity and thermal properties to test which material composite has the best cooling behaviour. We made both solid and perforated panels made of plastic, aluminium and clay.

1. 2.

To check itâ&#x20AC;&#x2122;s behavoir were created closed boxes with the frame for the panels on top to see the effect of cooling inside a volume. A nuetral panel was made to map the differences, For the measuring we used Arduino board with temperature and humidity sensors DHT and recorded graphs comparing all the panels with hydrogel to the neutral one.







solid Alumin perforated Aluminum

solid aluminium


Neutral solid Aluminum





perforated aluminium

Test showing difference in 0.3 degrees between the perforated aluminium panel and the neutral one. This difference happened because hydrogel dried fast.

Test showing difference in 3.4 degrees between the solid aluminium panel and the neutral one.






solid Plastic

perforated plastic

Test showing difference in 3.5 degrees between the solid plastic panel and the neutral one. This difference happened because hydrogel dried fast.




Test showing difference in 4.4 degrees between the solid plastic panel and the neutral one.


perforated Plastic

solid plastic


Neutral solid Plastic






solid clay



Test showing difference in 6.4 degrees between the solid clay panel and the neutral one. It is the best cooling result.


neutral solid clay

Test showing difference in 6.3 degrees between the perforated clay panel and the neutral one. The humidity rises to 70% because of perforations.






Graphs show the difference in temperature according to outside conditions. This distinction directly depends on the evaporation process. As it is shown in a small test the water evaporates faster in more heated environment. The faster evaporation happens the more cooling occurs.

Air dried

20 oC 2 days 5 ml of SAP


Dried with hot air


60 C 20 min 5 ml of SAP


This is analysys of the results from the test. The slope of the plotted lines represents the humidity and the magnitude in the negative x axis represents the drop in temperature. The clay reduces the temperature and increases the humidity in maximum.



These charts represent an overlay of our analysis with the comfort zone analysis of different climatic regions. The study includes three regions : 1. Riyadh : Hot and dry climate Perforated clay is the recommended material to increase the humidity and decrease the temperature the maximum. 2. Kuala lumpur : Hot and wet climate Perforated aluminum is the recommended material to not increase the humidity too much but decrease the temperature by 3 degrees. 3. Barcelona : Moderate temperature Plastic to decrease temperature at the same time allow for transparency.



The panel was fed with pipes connected to a pump to see the growth of hydrogel over time. This panel took 2 hours to be filled by hydrogel that grew from 2mm to 20 mm in diameter.



This maze like structure was created so that the water takes more time to travel the panel in order to give time for hydrogel to absorb water and also so that the hydrogel inhabits the panel more uniformly in time.



This research was to do with shading in buildings. Coloured hydrogel was locked in position in the panel so that when it is small there is light entering and when it is big (after feeding with water) there is shading and cooling.



Water from 1st valve into the water container around the geometry.

The walls in the middle are peforated so the water slowly passes throught into the hydrogel.

This design was created to have more uniform growth of hydrogel throughout the panel. According to different densities of SAP inside the transparent panel varieties of shading colored patterns can be created. This can be applied to surfaces and consequently to solar radiation.


2nd valve fills the other half of the pattern and creats 100% shading and cooling system


breathing system



A stoma is a pore, found in the epidermis of leaves, stems and other organs that is used to control gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening. We wanted to achieve kind of the same behavoir for the cooling.



Our next test was to create breathing skin to cover the hydrogel. The idea is that it opens according to the growth of the hydrogel when it absorbes water to create cooling. And the system works better when it is ventilated. This layer is made of silicone.



Proceeding from the previous tests with panels (temperature and humidity graphs) we choosed clay for the future models. In this prototype water absorbing fabric is used as a breathing skin holding the hydro spheres.



The same idea of breathing system occures in the cylindrical prototypes. Where hydrogel is kept by the fabric attached to the walls. While SAP swells it moves out with fabric through openings. In this case the whole coulmn can be hollow and used for ventilation while keeping these columns in the inside of the building volume to cool areas that are far away for the skin.

colomn with hydrogel

section growing hydrogel

covering layer of fabric

clay inside holding layer of fabric






Tracks in clay for water transfer.

In this prototype water tracks are created in clay. We used reaction diffusion patterns for it. As well there are hydrogel nests to position it.


The fabric layer expands at the points with hydrogel. As a result the cuts in the rubber layer open creating ventilation.


Mould for clay is lazercut and assembled in particles. In this prototype we tried oil based clay that can be baked at low temperatures but the porosity is very little so it didnt show good results.



We decided to use low temperature clay for the tiles. The one curvature prototype in this material was made completely manually. This prototype explores the double curvature possibility of the building skin where the hydrogel is evaporating water both inside and outside.



This research was done keeping in mind the possibility that the tiles do not need baking, which is a parallel research being done at IAAC.


Special thanks to Sofoklis Giannakopoulous



These tiles are 3D printed with the KUKA. In this case the fabrication technique openes up more possibilities as the tiles dont need moulds and this clay doesnt need baking therefore the need for fabric and moulds can be eliminated and the hydrogel can be embedded inside the 3D printed water channels during the fabrication process.

First test print


After changing the settings and the geometry.


These moulds are for a tile that has the water channels embedded into them, Also the curvature can made by milling so that the tiles are customised according to the form. They were made using CNC milling machine.



clay breathing layer

The tile consists of two layers of clay, fabric and hydrogel. The outside layer presents surface fiiled with opened volcanoes to create ventilation and access for water and air to hydrogel. The conical shape gives the specific direction for the growing spheres during the absorptoin. In between is the layer of fabric that soaks water and works as a liquid transmitter through all the system. Also because of the elasticity it can allow for the growth of hydrogel. The inside layer is a thin clay surface with bumps that transmits coolness to the building.

stretching fabric


clay supporting layer



We made 4 molds for the clay: two as a molding part and two as a press.




2. The moulds for the tiles were milled in wood by a CNC milling machine. The tiles need 2 days to dry and then to be baked inside a kiln at 1000 degrees.




The tile consists of two layers of clay, fabric and hydrogel. The outside layer presents surface fiiled with opened volcanoes to create ventilation and access for water and air to hydrogel. The conical shape gives the specific direction for the growing spheres during the absorptoin. In between is the layer of fabric that soaks water and works as a liquid transmitter through all the system. Also because of the elasticity it can allow for the growth of hydrogel. The inside layer is a thin clay surface with bumps that transmits coolness to the building.



We made a test comparing the humidity and temperature in the boxes covered one with hydroceramic tiles, one with clay tiles without hydrogel. The difference in temperature came up to 4 degrees. The difference in humidity was 40%

graph showing difference in temperature (4oC) and humidity (40%) between two closed climate systems - one covered with common tiles and the other covered with hydroceramic tiles




ceramic layer

hot air

holding textile

ceramic layer

cool air

cool air

cool air

cooling pavilion 100

future application 101

hydroceramic tile

Distribution of tiles covering the pavilion according to the solar radiation This is a case study of a cooling pavillion in barcelona. The building skin has been analysed according to the incident solar radiation and the density of hydroceramic is increased or decresed according to the radiation. So the water is evaporating more where the heat is the maximum.and lets one customise the use of material according to the needs.

shape of the pavilion allows to create the natural ventilation which is important for the whole system

solar radiation

distribution of tiles and â&#x20AC;&#x153;volcanoesâ&#x20AC;? filled with hydrogel



a medium window type AC consumes 1200 Wh 8 hrs / day 9600 Wh 30 days / month 288 kWh cost of electricity in BCN 0.15 euro per 1 kWh for 1 month 43.2 euro Lowering down the temperature by every degree, increases the power consumption exponentially. Just by setting the AC 1’ Celsius higher saves 7% of overall power consumption. With the HydroPanel you lower down 4’ Celsius from external temperature so you can save up to 28% of the overall electricity caused by 1 AC.

An average medium size consumes 1200 Wh of electricity. Every 1 kWh of electricity consumption results 0.7 Kg of CO2 emission. An AC usage in one month produces 288 x 0.7 = 201.6 Kg. By saving 28% of the AC electricity consumption we save 80.64 kWh. This means we reduce 56.448 Kg a month.

Cost of Production

The volume of one sphere is 2 cubic cm. 1 tile contains about 100 hydrogel spheres - which equals 200 cubic cm of water. To feed the panel for one sqm you need 3 Litre per sqm. (Which can be collected from rain water or grey water due to the “filter” property of hydrogel).


Cost of the panel Material 4 mm Glass Clay Hydrogel Total

80 cent 50 cent 60 cent 1.80 euro

equals 28 euro per sqm.


106 strategy/Cooling+Down+In+The+Heat#sli de_0

- Cooling Down In The Heat (Strategies) aa6e84f7949282b064bb13b83dc586f1#. U5dAL5SSwQ5

- Round shape reduces water loss: Pebble plants challenges/22-air-conditioner-costs

- Consumption





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