High Thermal Performance Design

Holistic Approach

High thermal performance design is essential for a successful all-electric heating and cooling (HVAC) project. It is actually more important if you wish to run your HVAC systems largely from your own solar power.

Take a holistic approach to your project design including high thermal performance. Request an indicative thermal performance Star Rating as soon as you can in the design process.

For building approval, it is a requirement of the National Construction Code (NCC) that new homes and renovations are energy efficient. The NCC requires that new or renovated homes in Victoria and most other states achieve a Star Rating of at least 6 out of 10.

Consider the factors affecting the thermal performance of your building design before undertaking your Star Rating to save time and money.

Your decisions around heating and cooling systems are affected by your building’s heat load requirements. Your decisions around other elements of your build will affect your heat loads. This includes your building structure, orientation and building product specifications.

Take the opportunity if you are renovating to create a high thermal performance design for your new section. 

Choose high performing insulation and window glazing because ceilings and windows account for around two thirds of your heat loss. Improve your thermal performance Star Rating with good shading, house orientation and room layout.

If your initial thermal performance assessment is less then 6 Stars then your design will need some revision.

Contact us to assist your thinking about thermal performance design, and all-electric heating and cooling options.

FirstRate5 Thermal Performance Rating Software
NatHERS Energy Rating Scheme

Thermal Performance Star Rating

The thermal performance Star Rating measures the efficiency of your building design and describes the likely heating or cooling loss from normal use over one year. It is like a Star rating for your fridge or dishwasher identifying energy efficiency.

To gain 10 Stars out of 10, your home would need to be completely passive requiring no mechanical heating and cooling equipment. In a state like Victoria with cold winters and hot summers, this is very difficult to achieve.

Use passive home concepts to create high thermal performance design. Try improving your Star Rating from 6 to at least 7 out of 10.


Your home’s thermal performance is calculated using approved software based on the Nationwide House Energy Rating Scheme or NatHERS. 

For a thermal assessment to be undertaken, you need to provide the following building plans:

  • Site plan
  • Floor plan
  • Elevations
  • Sectional views
  • Electrical plan

Also, key elements of your building structure need definition including:

  • Floor types
  • Wall types, external and internal
  • Ceiling types

Also, your building product specifications require definition including:

  • Floor, wall and ceiling insulation
  • Ceiling and wall colours
  • Window frames and glazing types
  • Roof and clerestory windows
  • External and internal doors
  • Thermal bridging
  • Air tightness
  • Floor coverings
  • Window coverings
  • Light fittings that penetrate ceilings
  • Sealed or unsealed exhaust fans
  • Ceiling fans
  • Shading

Factors Affecting your Star Rating

Consider the following, which have a significant impact on your Star Rating:

  • Ceilings
  • Windows and shading
  • Walls and floors

Looks at these specific areas:

  • Window coverings particularly over single glazed windows
  • Installing larger windows on the windward side and smaller windows on the leeward side for better natural ventilation
  • Minimizing downlights that penetrate your ceilings
  • Installing ceiling fans to aid summer cooling
  • Sealing exhaust fans to eliminate thermal bridging to the outside
  • Insulating walls and floors
Shading for Thermal Performance

Local Climate

Your thermal performance design starts with your local climate. Think through your building’s orientation to the sun and prevailing wind.

Victoria, for example, has a mild or cool temperate climate characterized by large temperature swings (diurnal range) between winter and summer. For a good energy rating you need a lot of northern windows, less eastern and western windows and minimal southern windows. This will maximize sunshine radiation and minimise heat loss through windows in winter.

A house with good thermal performance and Star Rating of 6 or more lends itself to all-electric heating, ventilation and cooling solutions. These solutions can be powered largely by your solar panels.

Hydrosol specializes in all-electric solutions including hydronic heat pumps. Hydronic heating is the best form of heating because it is silent and radiant. It does not blow heated air that can cause respiratory issues for asthma sufferers. Also, heat pumps can reverse cycle so can provide summer cooling. This is effective in a mild or cool temperate climate, particularly with ceiling fans.

Central Victoria Case Study

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