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 only design instrument or apparatus which will be used in the laboratory test.

Time and Place of the Study

The study will be conducted on December 2014 to March 2015 at Abellera Street, Poblacion, Kabacan, NothCotabato. Time, place, and surrounding temperature during the experiment will be strictly the same. The sample, Cogon grass, will be taken anywhere.

Operational Definition of Terms

Thermal resistance (R) – the property of the Cogon grass to resist heat. It is
Directly proportional to the thickness of the layer of the piled Cogon grass. The greater the thermal resistance, the better insulator the material is.
Thermal conductivity (k)–the property of Cogon grass which defines the its conductivity to heat. The lesser the thermal conductivity, the better insulator the material is.
Temperature gradient – the temperature difference of two systems or environment in which vertically piled Cogon grass get in between per its unit thickness.
Heat current (H) – the change in heat per change in time. It is directly proportional to the area of heat transmission and temperature difference between the two systems but inversely proportional to the thermal resistance.
Area of transmission (A) – the total area of piled Cogon grass exposed to temperature difference which is perpendicular the transmission of heat.

REVIEW OF RELATED LITERATURE

The following literature has direct bearing to the current study. Materials cited in this related literature are the traditional and globally used materials with their properties in which the researcher wishes to compare with.

BUILDING INSULATION MATERIALS

Insulation materials are thermal insulations used in the construction or retrofit of buildings. The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome.
Quite simply, all insulation regardless of type is good insulation. This is due to a number of defining characteristics: * All Insulation has the potential to reduce heat loss and CO2 emissions. * Energy conserved through insulation use far exceeds the energy used in its manufacture. * Insulation performance varies depending on the material type, giving a choice to the builder and specifier. * Therefore, we can safely say that all insulation is sustainable. * The more insulation that goes into a building the better as that will, of course, make it more energy efficient.
Whilst all insulation is beneficial, in order to define its sustainable credentials a number of factors must be taken into account. Firstly, the source of the material itself must be considered. The insulation materials can be broken down into three main subcategories: * Naturally Occurring Mineral – refers to inorganic fibrous insulation derived from natural mineral based substances. * Petrochemical – refers to man-made insulation derived from raw materials of petroleum or other hydrocarbon origin. * Organic – refers to insulation materials derived from living organisms.
Insulation choice is complex, as no one specific insulation type will fulfil one hundred percent of the criteria. Outlined below are a few points to be considered:
Embodied Energy This relates to the hidden energy within a product, which includes manufacturing processes and transportation. It relates to all the energy used from the inception of the product to its arrival on site. Low embodied energy is best achieved from organic insulation products. Embodied energy can increase significantly if products are imported or through the heating and melting down of raw materials.
Operational Performance Operational performance of the insulation relates to the product when ‘in situ’ and part of a building structure. The insulation material will influence the performance of the building throughout its lifetime and whilst the single biggest factor is thermal conductivity, other factors such as thermal mass, fire performance and ingress of water need to be considered as well.
Post Lifetime Recyclability Many insulation products are, in theory, recyclable. However, there are many contributory factors such as whether a recycling system is in place and at the time of demolition whether the insulation is stripped and removed from the building.

CATEGORIES OF INSULATION MATERIALS
Insulation may be categorized * by its composition (material) * by its form (structural or non-structural) * by its functional mode (conductive, radiative, convective). * Non-structural forms include batts, blankets, loose-fill, spray foam, and panels. * Structural forms include insulating concrete forms, structured panels, and straw bales.
Sometimes a thermally reflective surface called a radiant barrier is added to a material to reduce the transfer of heat through radiation as well as conduction.
CONSIDERATION OF MATERIALS * Climate * Ease of installation * Durability - resistance to degradation from compression, moisture, decomposition, etc. * Ease of replacement at end of life * Cost effectiveness * Toxicity * Flammability * Environmental impact and sustainability
TYPES OF INSULATION MATERIALS
SPRAY FOAM
Spray foam is a type of insulation that is sprayed in place through a gun. Polyurethane and Isocyanate foams are applied as a two-component mixture that comes together at the tip of a gun, and forms an expanding foam. Cementitious foam is applied in a similar manner but does not expand. Spray foam insulation is sprayed onto concrete slabs, into wall cavities of an unfinished wall, against the interior side of sheathing, or through holes drilled in sheathing or drywall into the wall cavity of a finished wall.
ADVANTAGES
* Blocks airflow by expanding and sealing off leaks, gaps and penetrations. * Can serve as a semi-permeable vapor barrier with a better permeability rating than plastic sheeting vapor barriers and consequently reduce the build up of moisture, which can cause mold growth. * Can fill wall cavities in finished walls without tearing the walls apart (as required with batts). * Works well in tight spaces (like loose-fill, but superior). * Provides acoustical insulation (like loose-fill, but superior). * Expands while curing, filling bypasses, and providing excellent resistance to air infiltration (unlike batts and blankets, which can leave bypasses and air pockets, and superior to some types of loose-fill. Wet-spray cellulose is comparable.). * Increases structural stability (unlike loose-fill, similar to wet-spray cellulose). * Can be used in places where loose-fill cannot, such as between joists and rafters. When used between rafters, the spray foam can cover up the nails protruding from the underside of the sheathing, protecting your head. * Can be applied in small quantities. * Cementitious foam is fireproof.
DISADVANTAGES
* The cost can be high compared to traditional insulation. * Most foams, with the exception of cementitious foams, release toxic fumes when they burn. * According to the U.S. Environmental Protection Agency, there is insufficient data to accurately assess the potential for exposures to the toxic and environmentally harmful isocyanates which constitute 50% of the foam material. * Depending on usage and building codes and environment, most foams require protection with a thermal barrier such as drywall on the interior of a house. For example a 15-minute fire rating may be required. * Can shrink slightly while curing if not applied on a substrate heated to manufacturer's recommended temperature. * Although CFCs are no longer used, many use HCFCs or HFCs as blowing agents. Both are potent greenhouse gases, and HCFCs have some ozone depletion potential. * R-value will diminish slightly with age, though the degradation of R-value stops once an equilibrium with the environment is reached. Even after this process, the stabilized R-value is very high. * Most foams require protection from sunlight and solvents. * It is difficult to retrofit some foams to an existing building structure because of the chemicals and processes involved. * If one does not wear a protective mask or goggles, it is possible to temporarily impair one's vision. (2–5 days)

TYPES * Cementitious * Phenolic * Polyisocyanurate (polyiso) * Polyurethane.

INSULATING CONCRETE FORMS ICF systems consist of interconnected foam boards or interlocking, hollow-core foam insulation blocks. Foam boards are fastened together using plastic ties. Along with the foam boards, steel rods (rebar) can be added for reinforcement before the concrete is poured. When using foam blocks, steel rods are often used inside the hollow cores to strengthen the walls.
RIGID-PANELS
Can be used to insulate almost any part of your home, from the roof down to the foundation. They provide good thermal resistance, and reduce heat conduction through structural elements, like wood and steel studs. The most common types of materials used in making foam board include polystyrene, polyisocyanurate (polyiso), and polyurethane.

STRUCTURAL INSULATED PANELS
Structural insulated panels (SIPs), also called stressed-skin walls, use the same concept as in foam-core external doors, but extend the concept to the entire house. They can be used for ceilings, floors, walls, and roofs. The panels usually consist of plywood, oriented strandboard, or drywall glued and sandwiched around a core consisting of expanded polystyrene, polyurethane, polyisocyanurate, compressed wheat straw, or epoxy.
Epoxy is too expensive to use as an insulator on its own, but it has a high R-value (7 to 9), high strength, and good chemical and moisture resistance.
SIPs come in various thicknesses. When building a house, they are glued together and secured with lumber. They provide the structural support, rather than the studs used in traditional framing.
ADVANTAGES
* Strong. Able to bear loads, including external loads from precipitation and wind. * Faster construction than stick-built house. Less lumber required. * Insulate acoustically. * Impermeable to moisture. * Can truck prefabricated panels to construction site and assemble on site. * Create shell of solid insulation around house, while reducing bypasses common with stick-frame construction. The result is an inherently energy-efficient house. * Do not use formaldehyde, CFCs, or HCFCs in manufacturing. * True R-values and lower energy costs.

DISADVANTAGES * More expensive than other types of insulation. * Thermal bridging at splines and lumber fastening points unless a thermally broken spline is used (insulated lumber).
FIBERGLASS BATTS AND BLANKETS
Batts are precut, whereas blankets are available in continuous rolls. Compressing the material reduces its effectiveness. Cutting it to accommodate electrical boxes and other obstructions allows air a free path to cross through the wall cavity. One can install batts in two layers across an unfinished attic floor, perpendicular to each other, for increased effectiveness at preventing heat bridging. Blankets can cover joists and studs as well as the space between them. Batts can be challenging and unpleasant to hang under floors between joists; straps, or staple cloth or wire mesh across joists, can hold it up.
TYPES
* Rock and slag wool. Usually made from rock (basalt, diabase) or iron ore blast furnace slag. Some rock wool contains recycled glass. Nonflammable. * Fiberglass. Made from molten glass, usually with 20% to 30% recycled industrial waste and post-consumer content.Nonflammable, except for the facing (if present). Sometimes, the manufacturer modifies the facing so that it is fire-resistant. * Some fiberglass is unfaced, some is paper-faced with a thin layer of asphalt, and some is foil-faced. Paper-faced batts are vapor retarders, not vapor barriers. Foil-faced batts are vapor barriers. The vapor barrier must face the proper direction. * High-density fiberglass * Plastic fiber, usually made from recycled plastic. Does not cause irritation like fiberglass, but more difficult to cut than fiberglass. Not used in USA. Flammable, but treated with fire-retardant.
NATURAL FIBER Natural fiber insulations (similar to mineral fiber and fiberglass insulation at 0.04 W/mK), treated as necessary with low toxicity fire and insect retardants, are available in Europe : Natural fiber insulations can be used loose as granulats or formed into flexible or semi-rigid panels and rigid panels using a binder (mostly synthetic such as polyester, polyurethane or polyolefin). The binder material can be new or recycled.
SHEEP’S WOOL INSULATION Sheep's wool insulation is a very efficient thermal insulator with a higher performance than glass fiber and no reduction in performance even when condensation is present. It is made from the waste wool that the carpet and textile industries reject, it is available in both rolls and batts for both thermal and acoustic insulation of housing and commercial buildings. Wool has the ability to absorb significant levels of condensation, 40% of its own weight, and yet still be dry. As wool absorbs moisture it heats up and therefore reduces the risk of condensation. It has the unique ability to absorb VOC gases such as Formaldehyde, Nitrogen Dioxide, Sulphur Dioxide and lock them up permanently.[31] Sheep's Wool Insulation has a long lifetime due to the natural crimp in the fiber, endurance testing has shown it has a life expectance of over 100 years.
WOOD FIBER
Wood fiber insulation is available as loose fill, flexible batts and rigid panels for all thermal and sound insulation uses. It can be used as internal insulation : between studs, joists or ceiling rafters, under timber floors to reduce sound transmittance, against masonry walls or externally : using a rain screen cladding or roofing, or directly plastered/rendered,over timber rafters or studs or masonry structures as external insulation to reduce thermal bridges.
COTTON BATTS Cotton insulation is increasing in popularity as an environmentally preferable option for insulation. It has an R-value of around 3.7 (RSI-0.65), a higher value than most fiberglass batts. The cotton is primarily recycled industrial scrap, providing a sustainability benefit. The batts do not use the toxic formaldehyde backing found in fiberglass, and the manufacture is nowhere near as energy intensive as the mining and production process required for fiberglass. Boric acid is used as a flame retardant. A small quantity of polyolefin is melted as an adhesive to bind the product together (and is preferable to formaldehyde adhesives). Installation is similar to fiberglass, without the need for a respirator but requiring some additional time to cut the material. As with any batt insulation, proper installation is important to ensure high energy efficiency.
LOOSE FILL Loose-fill materials can be blown into attics, finished wall cavities, and hard-to-reach areas. They are ideal for these tasks because they conform to spaces and fill in the nooks and crannies. They can also be sprayed in place, usually with water-based adhesives. Many types are made of recycled materials (a type of cellulose) and are relatively inexpensive.
AEROGELS
Skylights, solariums and other special applications may use aerogels, a high-performance, low-density material. Silica aerogel has the lowest thermal conductivity of any known substance (short of a vacuum), and carbon aerogel absorbs infrared radiation (i.e., heat from sun rays) while still allowing daylight to enter. The combination of silica and carbon aerogel gives the best insulating properties of any known material, approximately twice the insulative protection of the next best insulative material, closed-cell foam.
STRAW BALES
The use of highly-compressed straw bales as insulation, though uncommon, is gaining popularity in experimental building projects for the high R-value and low cost of a thick wall made of straw. When using straw bales for construction, the bales must be tightly-packed and allowed to dry out sufficiently. Any air gaps or moisture can drastically reduce the insulating effectiveness.
REFLECTIVE INSULATION AND RADIANT BARRIERS
Reflective insulation and radiant barriers reduce the radiation of heat to or from the surface of a material. Radiant barriers will reflect radiant energy. A radiant barrier by itself will not affect heat conducted through the material by direct contact or heat transferred by moist air rising or covection. For this reason, trying to associate R-values with radiant barriers is difficult and inappropriate. The R-value test measures heat transfer through the material, not to or from its surface. There is no standard test designed to measure the reflection of radiated heat energy alone.
Reflective aluminum foil is the most common material used as a radiant barrier. It has no significant mass to absorb and retain heat. It also has very low emittance values "E-values" (typically 0.03 compared to 0.90 for most bulk insulation) which significantly reduces heat transfer by radiation.

ADVANTAGES * Very effective in warmer climates * No change thermal performance over time due to compaction, disintegration or moisture absorption * Thin sheets takes up less room than bulk insulation * Can act as a vapor barriers * Non-toxic/non-carcinogenic * Will not mold or mildew * Radon retarder, will limit radon penetration through the floor
DISADVANTAGES
* Must be combined with other types of insulation in very cold climates * May result in an electrical safety hazard where the foil comes into contact with faulty electrical wiring
HAZARDOUS AND DISCONTINUED INSULATION Certain forms of insulation used in the past are now no longer used because of recognized health risks.
UREA-FORMALDEHYDE FOAM (UFFI) AND PANELS
Urea-formaldehyde insulation releases poisonous formaldehyde gas, causing indoor air quality problems. The chemical bond between the urea and formaldehyde is weak, resulting in degradation of the foam cells and emission of toxic formaldehyde gas into the home over time.
Furthermore, some manufacturers used excess formaldehyde to ensure chemical bonding of all of the urea. Any leftover formaldehyde would escape after the mixing. Most states outlawed it in the early 1980s after dangers to building occupants were discovered. However emissions are highest when the urea-formaldehyde is new and decrease over time, so houses that have had urea-formaldehyde within their walls for years or decades do not require remediation.
UFFI provides little mechanical strength, as the material is weak and brittle. Before its risks were recognized, it was used because it was a cheap, effective insulator with a high R-value and its open-cell structure was a good acoustic insulator. Though it absorbed moisture easily, it regained effectiveness as an insulator when dried.

ASBESTOS

Asbestos once found common use as an insulation material in homes and buildings because it is fireproof, a good thermal and electrical insulator, and resistant to chemical attack and wear. It has been found that asbestos can cause cancer when in friable form (that is, when likely to release fibers into the air - when broken, jagged, shredded, or scuffed). Some people exposed to asbestos develop cancer.
When found in the home, asbestos often resembles grayish-white corrugated cardboard coated with cloth or canvas, usually held in place around pipes and ducts with metal straps. Things that typically might contain asbestos:

MATERIALS AND METHODS

Materials

The researcher will gather enough Cogon grass and piled at certain uniform thicknessfor the determination of its thermal resistance. The researcher will design a box made of styrofoam and which divided into two compartments by the piled Cogon grass with one thermometer for each compartment to determine the temperature difference. The use of styrofoam in the test is highly appropriate to prevent heat flow from the surrounding to the system.other than heat flow from one compartment to the other. Styrofoam has the property of being the poorest conducting material with only 0.01 W/m·K.
In the laboratory test, the researcher will require a certain amount of ice placed in one compartment which will then be melted at time (t) due to temperature difference between the two system. Heat fusion of ice is 334000 J/kg.

Methodology

The researcher will: 1. gather and prepare the Cogon grass piled at certain uniform thickness. 2. Design an instrument (a box divided vertically upward by piled cogon grassinto two compartments) from which the experiment will be conducted. Specifically, the be made up mainly of styrofoam. 3. Put certain amount of ice place in one compartment. 4. Place a thermometer in each compartment. 5. Increse the temperature in the other compartment which has no ice causing an increase of temperature difference between compartments thus causing an increase of the rate of melting. 6. Record each compartment’s temperature just after the ice will melt. 7. Record the elapsed time or duration of melting. 8. Replicate the experiment at the same environment, time, and place.

LITERATURE CITED

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