Radiant floor heating:

• Runs hot water through loops of polyethylene tubing underneath the floor
• Setup multiple zones that cn be controlled independently
• + More efficient than forced air heating
• + More comfortable
• ~$10/sqft

Floor materials:

• Engineered wood
  • + Works well with radiant floor heating
  • $3-12 / sqft
• Solid or reclaimed wood
  • + Looks good, works well with radiant floor heating
  • - can be scratched
  • $3-12 / sqft
• Bamboo
  • - Can have a large carbon footprint
  • $3-8 / sqft
• Cork
  • + Well insulated, good sound absorbtion
  • Need to make sure to source from non-toxic brands
  • $5-10 / sqft
• Laminate

Things to look for in a flooring brand:

• Eligibility for LEED credits
• Eligibility for BuiltGreen Canada credits
• Greenguard certified
• PEFC (Pan European Forest Certification) certified
• FSC (Forest Stewardship Council) certified

Conclusion: Use radiant floor water heating with cork or laminate on top. Cost: $36,000 ($10 radiant heating + $10 cork) / sqft * 1800sqft

References:

• This Old House
• Ecohome flooring