Let Buildings Breathe



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Introduction













Let Buildings Breathe

THERMO-BIMETAL

2/28/2013

David Kang

BTT1O1

http://eborg2.com/revelation/rev17/city.gif

Contents




Introduction 4

Thermo-Bimetal 6

A Comparison: How Buildings Devolved 7

Skyscrapers and the Urban Heat Island 9

Thermo-Bimetal as a Solution 10

Works Cited 10




Introduction


Nowadays, in any city, the only buildings people can see are huge, dominating skyscrapers with floor-to-ceiling windows, masses of steel and glass built to look professional, impressive, and imposing. Most buildings, while they may have slightly different designs, all share the major shell that coats their outsides – an endless number of giant windows. Now then, compare a normal house to one of those skyscrapers. Even for a normal house, the heating and air conditioning costs become staggering when overused. Imagine how much one of those skyscrapers, then, with their thin, un-insulating windows that do nothing to expel heat, would need the air conditioning to keep everything inside functioning, including the people. http://eeeg.files.wordpress.com/2010/06/house_insulation.jpghttp://farm9.staticflickr.com/8474/8142624977_1c354b5d78_z.jpg

So here we are, the human race, pouring thousands upon million dollars just into air conditioning to keep these skyscrapers going. However, there are ways to fix this. The rest of this report will detail how a relatively old, but smart, and only a recently recognized technology involving thermo-bimetal can let these buildings breathe freely without wasting money or natural resources.


Thermo-Bimetal


Thermo-bimetal is an ingenious material, a kind that is surprisingly not used as much as it could be in the modern world. Thermo-bimetal is, simply, a material that can be manufactured by riveting, brazing, or welding two different metal strips or panels that expand at different rates as they are heated. This magnificent technology was invented by the British clockmaker and inventor John Harrison, the man who single-handedly solved the ‘longitude problem’ in the eighteenth century. With this, when the two different strips that are fused are heated, one strip will expand more than the other, causing the material to bend in one direction. http://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/bimetaal.jpg/300px-bimetaal.jpg

You can see above in the picture how when heat is applied to the material, the top metallic strip expands more than the bottom strip, causing the whole strip to bend downwards. This technology, for some time, has been used in different electrical appliances that need certain currents to run or stop running when the appliance itself reaches a certain temperature, such as fluorescent lamp starters, thermostats or lamp flashers.


A Comparison: How Buildings Devolved




Past

Present

http://blogs.smh.com.au/lifestyle/renovationnation/stannixpark3.jpg

http://us.123rf.com/400wm/400/400/vladitto/vladitto0908/vladitto090800028/5332003-underside-view-to-new-skyscraper-business-centre.jpg

Thick walls with insulating materials (e.g. straw, brick, mud) to retain and expel heat as needed

Floor-to-ceiling windows that cannot expel heat effectively according to need

Small windows and entrances to minimize wasted energy flow in and out

Massive amount of energy transmission between outside and inside the building

Net energy difference already close to zero – little need for air conditioning

Requires massive amount of air conditioning to keep facility habitable

Built for practicality – little wasted material or resources therefore a small carbon footprint

Built for appearance – a lot of wasted energy and resources therefore an enormous carbon footprint


Skyscrapers and the Urban Heat Island


So, how exactly do skyscrapers and their glass exoskeletons waste energy? This question can be easily answered by comparing the skyscrapers to greenhouses. With the advent of the steel and glass industry, and evolving engineering mechanics, the exterior surfaces of our buildings have become very similar to the walls and ceilings of greenhouses we can often find on farms. These greenhouses have a primary function, and that is to absorb and retain heat effectively, even in winter. They can do this due to the fact that sunlight transmits heat through the glass or plastic walls and heat up the ground in the greenhouse, but the heat cannot easily escape by itself. Skyscrapers are affected by the same effect. The heat is transmitted by sunlight through the giant windows, heating up the area inside, but the heat cannot escape. While thanks to this, skyscrapers rarely need heating, even in winter, a massive, sophisticated, and always active air conditioning system is required in the building to keep it habitable. Even in winter, it can be seen how the temperature of the interior of a building may skyrocket, requiring sufficient cooling. Along with this, a factor that contributes to the massive air conditioning cost is that the sunlight does not necessarily heat the entire building. When only one side of the building is facing the sun, only that area will be heated, and the air conditioning directed to that area. Due to the frequent changes and inconsistency of the air conditioning system, the cost becomes even more expensive and takes up even more resources to power the system. This effect of how skyscrapers heat up so easily is a major contributing factor to the ‘Urban Heat Island’ effect, because all of the buildings retain so much heat, causing urban cities to have higher temperatures of up to 12 degrees Celsius than surrounding rural areas. How the Urban Heat Island Effect can have a negative impact on the surrounding area can effectively be seen in the graph to the left. When the temperature goes over a certain point, the electricity demands increase, causing bigger drains on the fossil fuel reserves that generate the electricity, creating more air pollutants in the process including sulfur oxides, nitrogen oxides, and mercury contents. Along with this, the increased daytime temperature and reduced nighttime cooling lowers the general quality of life for the citizens. The elevated temperatures also lead to increased levels of bacterial and viral infections, causing more diseases to thrive in areas with more people.http://www.epa.gov/hiri/images/electricdemand-big.gif

Thermo-Bimetal as a Solution


The human skin is an excellent insulator and protection ‘device,’ in a way. Like thermo-bimetal, it changes with heat. When the body needs to expel heat, it opens sweat glands and pores to do so, and when it needs to retain heat, the pores close, tightening the fibers around the hair on the skin so that they stand erect, effectively keeping most of the heat inside the body. Architect and former biology researcher Doris Kim Sung thought that buildings need something like this. “Skin is the first defense of the body… Our building skins should be more similar to human skin.” (Doris Kim Sung, on TED) She decided to experiment with thermo-bimetal, a material that changes shape with heat, much like human skin. One example of her experiments is ‘The Bloom,’ as shown on the right, a structure that demonstrates how thermo-bimetal could function effectively on buildings. The small strips on the structure curl upwards with sunlight, allowing cool wind to blow through. With this sort of skin attached as an exoskeleton to buildings, they could keep heat inside when cold, and expel heat when hot. The best part about this technology is that due to the material automatically changing with heat, it requires no energy to maintain, and the material is relatively cheap. Buildings with this type of skin attached outside have already shown to be much more effectively insulated than before, such as the picture to the left, which depicts a developer’s building in China. It is constructed in the same glass-encased format as conventional skyscrapers, but is sheeted in the net of thermo-bimetal. According to the results, this building has apparently shown a 78% decrease in air conditioning costs, proving that the thermo-bimetallic skin is effective in doing its intended job.http://2.bp.blogspot.com/-wf6_l2hi9ye/uhgoyxx6agi/aaaaaaaaa30/hp2bmyjzpl4/s1600/2011-11-19+13.38.22.jpgbuilding with thermobimetal.bmp

Works Cited



Air Conditioning of Skyscrapers. (2011, August 4). Retrieved March 1, 2013, from DCCCD: http:\\www.dcccd.eu\ACR

Doris Kim Sung: Architect - Profile on TED. (n.d.). Retrieved March 1, 2013, from TED - Technology, Entertainment, and Design: http://www.ted.com/speakers/doris_kim_sung.html

EPA. (n.d.). Heat Island Effect. Retrieved March 4, 2013, from EPA: http://www.epa.gov/hiri/



Insulation in the Home. (2010, November 11). Retrieved March 1, 2013, from Epsom & Ewell Energy Group: http://epsom-ewellenergy.org.uk/category/home/insulation-home/

Kanthal AB. (2008, October). Kanthal Thermostatic Bimetal Handbook. Retrieved March 1, 2013, from http://www.kanthal.com/Global/Downloads/Materials%20in%20wire%20and%20strip%20form/Thermostatic%20bimetal/Bimetal%20handbook%20ENG.pdf

Pidwirny, M. (2012, July 17). Greenhouse Effect. Retrieved March 4, 2013, from Encyclopedia of Earth: http://www.eoearth.org/article/Greenhouse_effect?topic=54099

Sung, D. K. (2012, October). Doris Kim Sung - Metal That Breathes. Retrieved February 26, 2013, from TED - Technology, Entertainment, and Design: http://www.ted.com/talks/doris_kim_sung_metal_that_breathes.html



Wolfendale, A., & Taylor, J. (2007, January 22). John Harrison: Clockmaker and Copley Medalist. A Public Memorial At Last. Retrieved March 1, 2013, from Notes and Records of The Royal Society: http://rsnr.royalsocietypublishing.org/content/61/1/53.full
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