Recent Q&A

• Is a HERS rating mandatory in any state or city? And is the public benefiting from a HERS rating?

  Are there any US jurisdictions where home energy ratings are a requirement for selling a home?Normally the HERS rating would accompany a weatherization program or financial retrofit incentive program, as…

• Net zero-energy PV or PV sized for the A/C load?

  A rather big picture question - Net Zero Energy building standard is ramping up in Canada. It is obvious to many however the target should instead be Net Zero Carbon with…

• Is cooling adequate via natural ventilation?

  There was a lot of interest in natural ventilation I saw a while ago. Some people think this can also cool a house. Was this always a confusion of two…

• 成本的两倍stud wall with dense packed cellulose

  I want to compare the cost of a 'conventional' 2x6/batt/rigid foam wall to a double stud wall with dense packed cellulose. Wall should be around R35 to R40-effective. Are there…

• Cellulose for new walls – wet sprayed or dense packed?

  I would like to install cellulose as the main wall insulation inside 2x6 framing. There will also be 2 inches of rigid board insulation outboard. Climate zone is 6.What is…

• HFC versus HOC spray foam

  Demilec and other spray foam manufacturers are using HOC a zero GWP blowing agent.Does anyone know the ecological impact of these newer HOC spray foams? They claim the life cycle…

• Condensation within wall cavity in the cooling season

  Is it possible for water vapor from outdoors to condense inside the wall cavity (say against the back of the drywall) during a humid summer with the house cooler and…