Granny Flats

Region: All States

Assessor Question:

For outbuildings that don't require a planning permit (granny flat type structures), am I allowed to rate these separately using NatHERS software? 

My understanding was that they can not be considered a stand alone structure (as they share an allotment and do not have the required trio of a bathroom, kitchen and laundry making them a class 1 in it's own right) and is an extension to the existing dwelling, despite being a separate structure and so you would need to consider the existing building for the energy rating. I'm looking through the manuals and maybe I've missed something that says we are allowed to rate them separately? 

Maybe I'm over thinking it, this is what the RBS is asking for.

TPA Support Response:

• Granny Flat or Independent Living Unit are descriptors that infer a small dwelling that will be occupied by someone carrying out all the standard occupational activities of a dwelling including cooking and sleeping.
• As such they are small Class 1 buildings and accordingly can have building fabric energy efficiency compliance substantiated with a NatHERS Deemed to Satisfy rating.
• This will often entail using the NatHERS Technical Note Clause 5.3 proportional zone allocation set out for studio/bedsit apartments.
• A satellite portion of a house being bedrooms and/or bathrooms and/or living rooms but without a kitchen are considered to be a portion of the main house and cannot have separate compliance confirmed with a NatHERS rating.
• The alternative approaches in that case are Elemental Deemed to Satisfy, Performance Solution or Expert Opinion.