Passivhaus Certification Versus Energy Rating System
We answer many questions on the topic of Passive Houses and one of the questions that is particularly popular is how does Passivhaus Certification compare to the Energy Rating System in Australia?
Let’s start with a simple explanation of the star rating system…
The National House Energy Rating Scheme (NatHERS) was developed to help improve Australian homes by providing energy performance ratings and information.
NatHERS uses a 10 STAR rating system to provide estimates of a home’s thermal performance (heating and cooling needs). Star ratings are based on information about a home’s design, construction materials and the climate where it is built.
It takes into consideration (but not limited to):
· Climate, terrain, exposure and orientation
· Zoning (of rooms)
· Floors, Walls, Ceiling, Roof (Materials, construction methods, insulation)
· Windows (Materials, size, placement)
· Shading
The goal is to help make Australian homes more comfortable and keep energy costs to a minimum by understanding how energy is used to heat and cool a home. This information is then translated into smarter design choices.
In Victoria, FirstRate5 is a software program for thermal performance assessors which was originally developed by the Victorian Government to cover the majority of houses in Victoria.
A building permit can only be issued once the Energy Rating report has been completed and there are Stamped Plans with a minimum of 6 Star rating.
Once a permit has been issued, it is then the responsibility of the builder to make sure all of the plans are adhered to throughout the build.
Now let’s take a look at a certified Passivhaus…
A Certified Passivhaus is a home that is designed and built with the 5 Passivhaus Principles of Thermal Bridge Free Construction, Windows and Doors, Thermal Insulation, Air Tightness and Air Ventilation.
It is a house that requires very little energy to maintain a year round constant, pleasant temperature. With it’s mechanical air ventilation system it also provides fresh, filtered air 24/7 making it an exceptionally healthy home as well.
Part of the Passivhaus Certification process requires the design to be put through a modelling software system known as the PHPP (Passivhaus Planning Package) which helps to define a home’s design in order to meet the criteria of a Passivhaus.
During the process of the build, all 5 principles are adhered to. At the completion of the build a blower door test is done to ensure the minimum standards of air tightness and air exchanges are achieved.
The final stages of certification is providing full documentation of the entire building process and blower door tests with the application for official status to be granted.
The goals at the heart of the two different systems have the same direction in mind, however the certainty of achieving the desired outcomes is a much more calculated and documented approach with the Passivhaus Certification method of accountability.
