1. Insulation

2. Insulation
Thermal insulation is a materials that blocks or slows the flow of heat through the building envelope.
Vital to most green building designs because it allows spaces to retain what heat they have and avoid gaining excess heat from outside

3. Insulation
Insulation is primarily designed to prevent heat transfer from conduction and radiation
Resistance to conduction is measured by the R-value (higher thermal resistance = higher R-value)
Resistance to radiative heat transfer is measured by emissivity (high resistance = low emissivity and high reflectance)

4. Insulation
Conduction is the dominant factor when materials are touching each other
When there is an air gap between materials radiation becomes important
Convection usually becomes an issue when significant air pockets are involved

5. 2-categories
Fibrous or cellular products – resist conduction and can be inorganic (glass, rock wool, slag wool, perlite, vermiculite) or organic (cotton, synthetic fibers, cork, foamed rubber, polystyrene)
Metallic or metalized organic reflective membranes – block radiation heat transfer and must face open air space to work

6. Insulation

7. Insulation Because R-values are 1/conductance (U)
Doubling the thickness of insulation will not cut heat loss in half
Exponential decay of heat flow

8. Low-Emissivity Insulation (Radiation)
Radiative heat transfer may be important to avoid
Attics or warehouses where the sun heats the building’s skin excessively
Thin sheet of reflective material can make as much diff as adding many inches of conventional insulation
Usually called radiant barriers

9. Radiant Barriers Have low emissivity (.1 or less)
Have high reflectance (.9 or more)
Shiny reflective or white materials
Only reduce radiative heat transfer

10. Convection and Insulation
Convection through fluids (air) can also transfer heat
Unwanted convection through the building envelope can cause unwanted heat gains or losses through infiltration
Suppressing convection often makes insulation effective

11. Convection and Insulation
Convection within the building envelope hurts insulation as well
Still air is an excellent insulator, often used in insulation by small pockets of air
Foam insulation is better than batt insulation because there is less convection of air within the foam

12. Insulation
Fibrous or cellular products prevent conduction by keeping air still
Batt insulation traps air in a mat made from a low conductivity solid, glass or organic fiber
Open cell foam traps tiny bubbles of air or other gas in a poor conductor, however gas can still migrate
Closed cell foam, gas cannot travel from cell to cell

13. Insulation Materials Typically comes in 5 different forms Batting
Blown-in
Loose-fill
Rigid foam board
Reflective films

14. Batting/Blankets

15. Blown-in/Loose-fill

16. Foamed in Place

17. Rigid Board

18. Reflective

19. Working Together Diff forms can be used together
Usually higher density insulation should not be placed over top of lower density material that is easily compressed
Hot air rises by convection, so it generally pools at the underside of surfaces and conducts heat upwards into those materials
Radiant barriers are more effective at preventing heat from flowing downward through a space than up

20. Movable Insulation