INSULATION

GOAL:: To become aware of energy conscious designs and construction that will save energy, cost less to operate and will have less of a negative impact on the natural environment.

OBJECTIVES:: The student will demonstrate knowledge and understanding of the different types of insulation, their R-value, and their use.

GLOSSARY:: Convection - Heat movement of a fluid (usually air or water) by the circulation of that liquid based on temperature differences, e.g., hot air rises and cold air falls.; Diurnal - A daily event - day to night.; Fenestration - A term used to signify an opening in a building to admit light and/or air.; Hybrid - A heating or cooling system that combines passive and active elements.; R-Value - The tendency of a material to reduce the movement of heat through it.; Reflective - To bounce light or heat off. A mirrored type surface.

LESSON/INFORMATION:

The R-value of a material is its resistance to allow heat to pass through the material. The established performance of the surface area as a barrier to heat flow can vary according to the construction materials and the quality control used during construction. The use of R-value should be considered when responding to various orientations. It is critical that the insulation be installed properly to achieve the R-value rating.

The recommended minimum R-value standards of surface assemblies for Louisiana's two climatic regions are shown in Table A. Adjustments to these values should be made according to the individual site conditions and climate.


TABLE A
	Minimum R-values of Building Surfaces for North and South Louisiana
	Surface Areas	North	South
	Raised floors	11	0
	Perimeter slab	8	6
	Walls	19	19
	Fenestration	2	2
	Ceilings	30	26

Determination of the R-values varies with the envelope assembly. Composite R-values are determined by the individual characteristics of the materials used in the construction of the R-value assembly. Enhancement of envelope assemblies are primarily done by increasing the insulating quality or quantity which are limited by the depth of the cavity. The R-value of a composite surface assembly is determined by adding the R-values of the various components of the assembly including air surface films located in the exterior and interior. The picture below shows an example of the R-value components of a common brick-veneer wall section.

063b

Increases in the R-value of cavities have an economic point of no return which will vary depending on the energy rates to which the project is subject. R-values for various building materials can be found in Table B.

TABLE B

R-values of Building Materials

R-value per Inch Material

0.20 Common Brick

0.54 8" Hollow Clay Tile

0.58 8" Concrete Block

0.08 Concrete

0.02 Stucco

0.79 Wood Siding

1.25 Soft Woods

0.45 1/2" Gypsum Board

1.25 Plywood

0.44 Asphalt Shingles

0.33 3/8" Built-up Roof

0.05 1/2" Slate

0.94 Wood Shingles


TABLE B
R-values of Building Materials
R-value per Inch	Material
0.20	Common Brick
0.54	8" Hollow Clay Tile
0.58	8" Concrete Block
0.08	Concrete
0.02	Stucco
0.79	Wood Siding
1.25	Soft Woods
0.45	1/2" Gypsum Board
1.25	Plywood
0.44	Asphalt Shingles
0.33	3/8" Built-up Roof
0.05	1/2" Slate
0.94	Wood Shingles

Insulation has the property of heat storage, which provides a time lag for heat penetration. The amount of heat passing through the assembly will vary due to the heat applied and the time interval.

The choice of insulation material to be used in a building envelope assembly is limited by the thickness of the cavity and the required R-value. Some insulation material thermal resistance value ratings are given in Table C.


TABLE C
R-value of Insulation Materials
R-value per Inch	Materials
3.6 - 7.5	Foams
2.8 - 3.8	Cellulose
2.5 - 4.0	Perlite
2.8 - 3.7	Rockwool
3.2 - 3.5	High Density Fiberglass
2.2 - 3.2	Fiberglass
2.4 - 3.0	Vermiculite

Reflective insulation consists of a single or multiple-layer build-up of reflective materials which include enclosed air spaces. Insulation can be used in a fixed assembly or in a movable configuration depending on design criteria. Movable insulation can be used in fenestration areas where diurnal patterns require the opening and closing of envelope surfaces. Various types and methods of movable insulation can be incorporated into a design. These types include shades or curtains, and solid or louvered panels. Some of the variations of shades and curtains include quilted, self-inflating, and laminated. Methods of movement include sliding, folding, rolling, hinged, and completely removable. Directions of movement and locations of insulation assemblies can vary also. The insulated material must fit tightly in the window space. Gaps around the edges will cause heat loss by convection.

Reflective surfaces acting as radiant barriers can be applied to movable insulation surfaces to prevent heat transfer. Insulated curtains or shutters are an example of movable insulation. One hybrid system of movable insulation uses beaded insulation material which is blown into the cavity of the space between double glazing and removed to a storage area when not required. Movable insulation surfaces can be operated manually or automatically integrated into the design to act as reflective surfaces for use in daylighting and as summer shading devices.

ACTIVITY 1:: Indicate whether the statements below are true or false.; ____1. R-value is the resistance of a material to the flow of heat through it.; ____2. R-values can be added up.; ____3. Even an air film on the surface has insulation value.; ____4. All materials have the same R-value.; ____ 5. Insulation can be moved from one place to another.; ____ 6. Enclosed dead air space between materials has insulation value.; ____ 7. Reflective materials can work like insulation by reflecting heat away.; ____ 8. Movable insulation works best covering glass.; ____ 9. Movable insulation is always electrically operated.; ____10. For movable insulation to be effective, it must fit tightly in the glazed opening.

ACTIVITY 2:: Find materials to build an insulated curtain and an insulated shutter. Then design ways of putting the material together to cover a window. The movable insulation can be attached like curtains, shades or shutters or it could be stored somewhere else.

TEACHER'S NOTES:: 1. Answers to True/False:; 2. Have the students collect samples of many different kinds of materials, i.e., wool, quilt batting, cotton, rigid insulation boards, etc. Maybe you could find an ambitious student who wanted to build some for his room at home. Let all students see his process and final product.

RECOMMENDED READING:: Solar Energy: Fundamentals in Building Design. B. Anderson. New York: McGraw-Hill. 1977.; Natural Louisiana Architecture. Cazayoux, Hebert and Winn. Baton Rouge, LA: Louisiana Dept. of Natural Resources, 1991.

REFERENCES:: Natural Louisiana Architecture. Cazayoux, Hebert and Winn. Baton Rouge, LA: Louisiana Dept. of Natural Resources, 1991.

Comments or questions to: TechAsmt@LA.GOV

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