NatHERS Assessment involves modeling a dwelling in a NatHERS certified thermal simulation software package, defining site conditions and finally thermal simulation of the model. In performing a NatHERS assessment certain established guidelines and protocols has to be followed in order to preserve consistency and fair comparison of different dwellings with different climate conditions and when a different computer software is used for NatHERS assessment.
NatHERS Assessment is principally based on the concept of thermal comfort of a habitable zone in a residential space. NatHERS scheme defines a zone's thermal conditions in which the occupants of that area will feel comfortable with regular clothing. Based on the climate zone of the development these conditions are slightly different. The building is modeled with a computer software package and the amount of heat that must be added or removed from each zone of the dwelling to make it comfortable for occupation is calculated. This heating and cooling loads are then represented in form of NatHERS ratings which is in form of star bands from 0 to 10 stars.
NatHERS Assessment Process
This section briefly summarizes the steps that needs to be taken in a normal NatHERS assessment for a single dwelling development;
Before a NatHERS assessment can be performed the following set
of information must be determined by the NatHERS assessor as a minimum required;
- Site Information: Area, Orientation of true north, Climate zone (post code or address), Overshadowing elements like adjacent buildings, Lot and DP number of the development site, areas of landscape, total area of roof.
- Dwelling Information: Complete geometry, layout and usage of each room, construction materials for all external and internal walls, floors, ceilings and roofs, Geometry and specifications of all shading elements and eaves
- The dwelling is then modeled by the NatHERS assessor to introduce the building to the computer software package to perform a NatHERS assessment.
- Based on the performance of the building a certain NatHERS rating is determined from the NatHERS assessment and allocated to the dwelling in form of a star rating.
- In NSW the heating and cooling loads of the assessment are being entered in the BASIX online tool instead of the star rating so those are the numeric outputs of a NatHERS assessment in NSW.
- Building thermal model will be uplodaed into the Government HStar portal and a set of documents are being produced by the government portal. These documents are then being used for Development Application submission as well as stamped plans and the BASIX certificate if applicable.