Two sets of solar rules, one for established suburbs, another for new suburbs

The government was looking to address complaints about its 2013 changes to solar access - essentially, the extent to which shadows cast by a building on one block can impact a neighbour.

While the 2013 changes (variation 306) were designed to stop new houses over-shadowing their neighbours, the government points to unintended problems - with people digging new homes low into blocks and building houses away from their southern boundaries to meet the new rules, creating "lopsided" houses in the streetscape and creating under-used space on the southern boundary.

The new solar rules (variation 346) allow an increase in the height of the building envelope. The government says it "rectifies a situation where an existing home has a level of protection which impedes their neighbour's ability to effectively develop their site" and "balances the outcome so both sides of the fence have reasonable access to sunlight so as not to favour one side too much".

But after more than 100 public submissions, divided between builders and industry groups who liked the proposed changes, and others who didn't, it has decided to implement the changes for new estates only in the first phase - with more work on solar access in existing suburbs. The result is a double set of solar access rules - one for established suburbs and one for new suburbs.

For new suburbs, including Molonglo, Throsby and west Belconnen, the height of the solar fence (an imaginary fence on the boundary) along a neighbour's northern boundary (the southern boundary of the person who is building) will change from 2.4 metres to 3 metres.

New homes will have to have north-facing window areas in the daytime living area that receive at least four square metres of sunlight on the winter solstice.

Planning Minister Mick Gentleman said the change would allow "slightly more shadow on the northern boundary" but in many cases the shadow would be low enough to not shade normal windows.

In Coombs and Wright, different rules will apply in different parts of the suburbs. The existing parts of Coombs and Wright will have the stricter solar rules, but houses in the new parts of the suburb can be built under the more permissive solar rules.

The Master Builders Association said the change was "important and sensible", but the double set of rules set a "worrying precedent".

"The decision to split the variation is the result of a handful of self-appointed individuals from the privileged inner suburbs effectively saying "not in my backyard"," ACT deputy executive director Michael Hopkins. "The Nimbys have preserved their exclusive environs at the cost of the entire community and sensible planning."

Owners of Mr Fluffy blocks would have to comply with more restrictive building rules than existed when their original house was built, he said.

The changes take effect at the end of next week.

Mr Gentleman said the government would keep working on solar access rules for existing suburbs.

"We have more work to do to strengthen solar access across the territory in existing areas. "