Title: Insulation Overview - GreenBuildingAdvisor
Headings: Insulation Overview
Insulation Overview
The Job of Insulation Is to Slow Heat FlowUPDATED 11/16/2012
ABOUT INSULATION
Thicker is better
It takes more than just insulation to slow heat
THERMAL BRIDGING IS CONDUCTION IN ACTION
R-VALUE MEASURES HOW WELL INSULATION WORKS
Heat flows from hot to cold; it can’t be stopped, but it can be slowed
Common insulation types and their R-values
Green homes go beyond code minimum
DOE recommended R-values for various parts of a house
AIR AND MOISTURE ARE PART OF THE PICTURE
Insulation can’t work in a wind tunnel
Moisture can piggyback on air
FURTHER RESOURCES
Fine Homebuilding
Environmental Building News:
Oak Ridge National Lab:
Home Energy Magazine:
Energy Star Homes:
Green Building Advisor:

Content: Building scientists call this phenomenon “thermal bridging” because the studs or rafters bridge the space between inside and outside the thermal envelope. If you look for it, thermal bridging can sometimes be seen from either inside or outside. Inside, it can cause a problem called ghosting, or cold stripes behind the drywall during winter. These cold stripes can encourage condensation that leads to the accumulation of dust particles on the drywall; eventually, visible vertical stripes may form. Outside, you can see the effect of thermal bridging in snow-melt patterns on roofs and drying patterns on walls. A continuous layer of rigid foam installed on the inside or outside of a wall or roof drastically reduces thermal bridging through the framing. R-VALUE MEASURES HOW WELL INSULATION WORKS
Heat flows from hot to cold; it can’t be stopped, but it can be slowed
If we measure the rate at which heat flows through a building material or building assembly—for example, a wall or a roof—we can calculate a number (the R-value) to indicate its insulating ability. The higher a material’s R-value, the better the material is at resisting heat flow through conduction, convection, and radiation (outlined above).