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Cogon Grass as Heat Insulator

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Cogon Grass as Thermal Insulator
In: Science
Cogon Grass as Thermal Insulator
COGON GRASS AS THERMAL INSULATING MATERIAL

KRISELLE ANNE A. GERPACIO

A Thesis Outline Submitted to the Department of Civil Engineering, College of
Engineering and Computing, University of Southern Mindanao,
Kabacan, Cotabato in Partial Fulfillment of the
Requirements for the Degree of

BACHELOR OF SCIENCE IN CIVIL ENGINEERING

DECEMBER 2014

INTRODUCTION

Significance of the Study

Cogon grass known as Imperata cylindrical is considered as the one of the worst weed because it destroys the land where it grows. It deteriorates the nutrients of the soil thus creating problems to farmers. Hence, the researcher would like to study if this grass can be a substitute as thermal insulating material. If it can be an alternative, this research would really give great help to many farmers.

Objectives of the Study

The main objective of this study is determine whether Cogon grass can be a substitute as thermal insulator as compared to other traditional thermal insulating materials. Specifically, this study aims to: 1. determine the thermal resistance (R) of Cogon grass as thermal insulating material; 2. determine the thermal conductivity (k) of Cogon grass as thermal insulating material; 3. determine how much heat (Q) trasmit to the layer of the Cogon grass per second; and, 4. determine how much is the temperature gradient or temperature difference per unit thickness of piled Cogon grass.

Scope and Limitation of the Study

The study will be limited only to to parameters involving computations for thermal resistance and other properties of Cogon grass, and determining whether it can be an efficient substitute to other traditional insulating materials for roofing. Parameters such as cost analysis, production, and installation process to roofs are not included in the study. The sample material will be taken from anywhere. The laboratory test will be replicated thrice at the same temperature, time, and place, and the researcher will...

Heat insulation * * * by Chris Woodford. Last updated: April 25, 2016.
If you're out and about in winter and you're feeling cold, chances are you'll put on a hat or another layer of clothing. If you're sitting at home watching television and the same thought strikes you, you're more likely to turn on your heating. Now what if we switched the logic around? What if you ate more food whenever you felt cold and stuck a woolly hat on top of your house each winter? The first wouldn't make much difference: food supplies the energy your body needs, but it doesn't necessarily make you any warmer right there and then. But putting "clothes" on your house—by insulating it—is actually a very good idea: the more heat insulation you have, the less energy escapes, the lower your fuel bills, and the more you help the planet in the fight against global warming. Let's take a closer look!
Photo: Aerogel is one of the world's newest and most exciting insulating materials. Put a slab of aerogel between a gas flame and some wax crayons and the crayons won't melt: the aerogel stops virtually any heat flowing through. One day, we could make all our windows out of aerogel—but scientists have to figure out how to make it transparent first! Photo by courtesy of NASA Jet Propulsion Laboratory (JPL).
How does heat escape from your home?

Why does heat escape from your home in the first place? To understand that, it helps to know a little bit about the science of heat. As you probably know, heat travels in three different ways by processes called conduction, convection, and radiation. (If you're not sure of the difference, take a look at our main article on heat for a quick recap.) Knowing about these three types of heat flow, it's easy to see lots of ways in which your cozy warm home is leaking heat to the freezing cold world all around it: 1. Your house is standing on cold soil or rock, so heat flows down directly into the Earth by conduction. 2. Heat travels by conduction through the solid walls and roof of your home. On the outside, the outer walls and the roof tiles are hotter than the atmosphere around them, so the cold air near to them heats up and flows away by convection. 3. Your house may seem like a big complex space with lots going on inside in but, from the point of view of physics, it's exactly the same as a camp fire in the middle of vast, cold surroundings: it constantly radiates heat into the atmosphere.
Artwork: Where does the heat escape in a typical home? It varies from building to building, but these are some rough, typical estimates. The walls give the biggest heat loss, followed by the doors and windows, the roof, and the floor.
The more heat escapes from your home, the colder it gets inside, so the more you have to use your heating and the more it costs you. The more you use your heating, the more fuel has to be burned somewhere (either in your own home or in a power plant up-state), the more carbon dioxide gas is produced, and the worse global warming becomes. It's far better to insulate your home and reduce the heat losses. That way, you'll need to use your heating much less. The great thing about home insulation is that it usually pays for itself quite quickly in lower fuel bills. Before long, it's even making you money! And it's helping the planet too.
How heat insulation works

Suppose you've just poured yourself a hot cup of coffee. A fundamental rule of physics called the second law of thermodynamics says it's never going to stay that way: pretty soon, it's going to be a cold cup of coffee instead. What can you do to postpone the inevitable? Somehow you need to stop heat escaping by conduction, convection, and radiation.
The first thing you could do is put a lid on. By stopping hot air rising and falling above the cup, you'll be cutting down heat losses by convection. Some heat is also going to be disappearing through the bottom of the hot cup into the cold table it's standing on. What if you could surround the cup with a layer of air? Then no conduction could take place. So maybe have a second cup outside the first one with an air gap (or, better still, a vacuum) in between. That's convection and conduction just about licked, but what about radiation? If you were to wrap aluminum foil round the outer cup, any infrared radiation the hot coffee gives off will be reflected back inside it, so that should solve that problem too. Apply all three of those solutions—a lid, an air gap, and a metallic coating—and what you have is effectively a vacuum flask: a really effective way of keeping hot drinks hot. (It's also good at keeping cold drinks cold, because it stops heat flowing in just as effectively as it stops heat flowing out.) It's worth noting, just in passing, that most takeaway stores give you hot drinks in nasty-tasting polystyrene containers. Ever wondered why? The answer is simply that polystyrene (and especially expanded polystyrene, filled with air—the crumbly kind you get in packaging materials) is a superb heat insulator (check out the table below and you'll see it rates better than double- and triple-glazing).
Photo: Vacuums coated with metal are among the best insulators, but they're not always suitable for everyday uses. In the late 1980s, two scientists working at the National Renewable Energy Laboratory, David Benson and Thomas Potter, developed a more practical way to use this technology called compact vacuum insulation (CVI). The outer metal plates, held apart by ceramic spacers, seal an insulating vacuum inside. Photo by Warren Gretz courtesy of US Department of Energy/National Renewable Energy Laboratory (DOE/NREL).
The best way to insulate your home
Now, unfortunately, we can't build our houses exactly like a vacuum flask. We have to have air to breathe, so a vacuum's out of the question. Most people like windows too, so living in a sealed box lined with metallic foil isn't that practical either. But the basic principle of cutting down heat losses from conduction, convection, and radiation still applies nevertheless.

Walls
Many homes, for example, have what are called cavity walls with two layers of brick or blocks between the inner rooms and the world outside and an air gap between the walls. The air gap reduces heat losses from the walls by both conduction and convection: conduction, because heat can't conduct through gases; convection, because there's relatively little air between the walls and it's sealed in, so convection currents can't really circulate.
By itself, air isn't the best insulating material to have between your walls. It's actually far more effective to have the cavities in your walls filled with expanding foam or another really good insulating material that stops heat escaping. Cavity-wall insulation, as this is known, takes only hours to install and costs relatively little. Cavity walls are often filled with loosely packed, air-filled materials such as vermiculite, shredded recycled paper, or glass fibers (specially treated to make them fireproof). These materials work in exactly the same way that your clothes work: extra layers of clothing make you warmer by trapping air—and it's the air, as much as (or more than) the clothes themselves, that stops heat escaping.
Photo: Reduce the energy losses from your home by filling the walls full of foam insulation. This eco-home is being insulated with Icynene, a plastic insulation material similar to that used in pillows and mattresses. Photo by Paul Norton courtesy of US Department of Energy/National Renewable Energy Laboratory (DOE/NREL).
Which are the best home insulation materials?

Some forms of insulation are better than others, but how can you compare them? The best way is to look out for a measurement called R-value. The R-value of a material is its thermal resistance: how effectively it resists heat flowing through it. The bigger the value, the greater the resistance, and the more effective the material is as a heat insulator. * Single glass: 0.9. * Air: 1 (0.5-4 inch air gap). * Double-glazing: 2.0 (with 0.5 inch air gap). * Vermiculite: 2.5 per inch. * Fiberglass: 3 per inch. * Triple-glazing: 3.2 (with 0.5 inch air gap). * Expanded polystyrene: 4 per inch. * Polyurethane: 6-7 per inch * Polyisocyanurate (foil-faced): 7 per inch. * Aerogel: Space-age insulating material: 10
Photo: You can reduce heat losses through your floor by building your home on a thick insulating material like this, which has an R value of 30. Photo by Paul Norton courtesy of US Department of Energy/National Renewable Energy Laboratory (DOE/NREL).
Roof
Since warm air rises, plenty of heat escapes through the roof of your home (just as lots of heat escapes from your body through your head, if you don't wear a hat). Most people also have insulation inside the roof (loft area) of their homes, but there's really no such thing as too much insulation. Loft insulation is generally made from the same materials as cavity-wall fillings—such things as rock wool and fiberglass.
Radiation losses
Wall and roof insulation cuts down on heat losses by convection and conduction, but what about radiation? In a vacuum flask, that problem's solved by having a reflective metallic lining—and the same idea can be used in homes too. Some homeowners install thin sheets of reflective metallic aluminum in the walls, floors, or ceilings to cut down on radiation losses. Good products of this kind can reduce radiation losses by as much as 97 percent. You can find out more by searching on "reflective insulation" or "radiant barrier" in one of the Google boxes on this page.

That still leaves the windows as a major source of heat loss, but there are ways to tackle that problem too. Double-glazed windows have two panes of glass separated by a sealed air gap. The air stops heat losses by conduction and convection, while the extra pane of glass reflects more light and heat radiation back into your home and reduces heat losses that way too. You can have your windows treated with a very thin reflective metallic coating or made from special thermal glazing (such as Pilkington-K, which traps heat a bit like a greenhouse) that reduces heat losses even further. (Read more in our main article on heat-reflective windows.)
Generally, the more insulation you have, the warmer you'll be. But the amount you need varies depending on where you live and how cold it gets.
Photo: Double glazing: the air gap between the two panes of glass provides heat insulation—and soundproofing too. Photo by Warren Gretz courtesy of US Department of Energy/National Renewable Energy Laboratory (DOE/NREL).
Chart: Switching from single- to double- or even triple glazing can make a big difference (darker blue), especially if you use low-e, heat-reflective glass (lighter blue). The numbers shown are R-values, with a 0.5 inch air gap. * * *
Find out more
On this website * Energy saving tips: This is our more general look at ways to save energy at home, at work, and as you travel from place to place. * Eco homes: If green issues are your prime motivator, why stop at insulation? Why not consider the entire environmental impact of your home. * Heat: The science of heat energy explored in more detail. * Passive solar: Stopping heat from escaping is a good thing, but so is letting in heat from the Sun to reduce your energy bills. That's the basic idea behind passive-solar buildings.
On other websites * Energy Saving Trust: Lots of great advice on home energy efficiency from this UK charity. The general advice applies to people outside the UK too. * DoE: Insulation Fact sheet: A great introduction to the theory of insulation, with lots of practical advice too. * US DoE: Energy Efficiency and Renewable Energy: Insulation and Air Sealing: More practical advice from the DoE. * Energy Saver: Insulation: A great collection of material from energy.gov, including comparisons of different insulation materials, where and how to insulate, and the differences between insulating old and new buildings. * Smarter Heating: David MacKay considers the physics behind home heating: how can you cut your fuel bills and help the planet? This is a chapter from his superb book Sustainable Energy—Without the hot air. * The 40% House: This excellent research project by Oxford University's Dr Brenda Boardman looked at ways of cutting household energy emissions by 60 percent from existing homes. * Insulation Contractors Association of America: FAQ: This brief page has answers to about a dozen of the more common household insulation questions and good practical guidance on getting reputable, professional contractors to insulate your home. * Insulation Institute: Explains what insulation is and how and why you should insulate your home.
Books and reports * The Energy-Efficient Home by Patrick Waterfield. The Crowood Press, 2012. A short primer written in clear, non-technical prose. * Energy-Efficient Home Manual: Expert Guidance on Saving Energy and Conserving Water by Reader's Digest, 2007. A DIY manual with an emphasis on reducing heating losses and fuel costs.
Articles
* 90% Of U.S. Homes Under Insulated, Research Finds: Clean Technica, October 2, 2015. A study by the North American Insulation Manufacturers Association (NAIMA) reveals massive scope for improvement in the United States. * Could Norway's home insulation methods save lives elsewhere: BBC News, December 31 2013. Colder countries such as Norway have lower winter death rates because their homes are better insulated. * Insulating your home? Try recycled materials from curtains to carpets by Joanne O'Connell. The Guardian. April 24, 2014. Waste from the textile industry could make perfect insulation, killing two eco birds with one stone.

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