Did you ask? Why HempCrete? Here are just a few Key Properties

THERMALMASS™ Insulation
Negative Carbon
Low Density
Clean Air
High Thermal Resistance (R-Value = 2.5 - 3.0 per inch)
High Thermal Inertia
Vapor Permeable (breathable)
Design Flexibility (adjustable thickness)
Fire and Pest Resistant (NO Termites)
Significantly Reduce Co2 Emissions
Inherently Airtight
No Waste
No Mold
No Termites
No Dry Rot
Natural Substrates for Plasters and Renders
Low Air Infiltration
ZERO Land Fill at end of life
http://en.wikipedia.org/wiki/Hempcrete