Insulation is a key part of any passive designed home, helping to keep heat inside the home in winter and outside the home in summer.


Insulation is a material that resists or blocks the flow of heat energy. For insulation to be effective, it should work in conjunction with good passive design.





Forms of Insulation

Insulation products come in two main categories:


  • Bulk
  • Reflective


Bulk insulation uses pockets of trapped air within its structure to resist the transfer of conducted and convected heat.


Bulk insulation comes in many forms:

  • glass wool, batts and rolls (often made from recycled materials)
  • wool, batts and loose fill
  • cellulose fibre loose fill (often made from recycled paper fibres)
  • polyester, batts and rolls (often made from recycled materials)
  • polystyrene, expanded (EPS) or extruded (XPS), as rigid boards


Reflective insulation mainly resists radiant heat flow because of its high reflectivity and low emissivity (ability to re-radiate heat).

Reflective insulation is most commonly used as:

  • Sarking
  • Concertina batts
  • Multicell batts

Insulation Mistakes

Insulation is only effective if installed correctly. The two most common mistakes we see are:

  • Gaps in the insulation (areas that are missed or removed by trades)
  • Crushed insulation (bulk insulation is only effective if it has its full depth)

Thermal Bridges

Thermal bridges are pathways for heat and cold to cross from the inside to outside through floor, walls and roof components. Thermal bridges reduce the effectiveness of insulation and can also lead to condensation problems.

Most often thermal bridges are structural elements such as the frame or structural steel that penetrate through the insulation layer. In cold climates like in North East Victoria metal frames can have large negatives effect on your homes thermal performance.

Where possible thermal bridges should be removed with good design and detail.


Our favourite resource from understanding all the elements of Solar Passive Design is