Most of the growth we're expecting in Porirua is in greenfields developments, however I think we should also be encouraging intensification of existing built-up ares.
When the council was developing its Growth Strategy last year, I made a submission on the benefits of intensification versus greenfields development.
If cities can accommodate population growth at higher densities, or within existing urban areas, or both, then you need less greenfield land for new housing. Under the government's National Policy Statement on Urban Development Capacity, PCC has to make available enough land for the projected growth. The availability of suitable land is an issue in the Wellington region and is a limit to growth.
Research shows that when density increases beyond a certain level, car use declines in favour of public transport, walking, and cycling. That means fewer car parks needed in commercial areas, and fewer CO2 emissions. Spreading out over greenfields developments increases the number of cars driven and the distance they're driven, with more CO2 emissions.
If you have surplus infrastructure capacity in urbanised areas, adding more people to these areas makes more efficient use of public urban infrastructure such as the three waters, as well as “soft” infrastructure such as schools and social services.
There is less water runoff than there would be from new roads and paths in new subdivisions, which is an important issue for Porirua, where a lot of the water from new developments will go into the harbour or possibly threaten Taupō Swamp.
There is a greater choice in housing — size, style and cost — and increased security for residents, with greater opportunities for social interaction and support.
It's also a lot cheaper. According to research from Curtin University, quoted in a presentation to a Planning Institute conference in 2013 comparing infrastructure costs (services, transport & health) for 1,000 dwellings (in $AUD):
- Infill housing infrastructure costs = $309m
- Expansion housing infrastructure costs = $653m
Development in already urbanised areas would play to our city’s strengths rather than spreading our resources over an ever-wider territory.
I know it's not universally popular — not everyone wants more neighbours living closer to them — but I think the benefits outweigh the disadvantages of both intensification and its alternatives.
PCC is intending to make intensification easier in the new District Plan, which is great. However, PCC needs to actively encourage intensification. The District Plan can remove barriers and restrictions, but it's disappointing the Growth Strategy didn't make intensification the preferred option over greenfields developments (or at least equal to it). It does assume there will be more intensification around public transport hubs, and I think PCC should look at incentives for people wanting to subdivide that would encourage them. Forget about a level playing field — it should skew the field in favour in higher density housing in existing urban areas.
For instance, the District Plan insists on two off-road car parks for every dwelling larger than 75m2, which is based on an assumption all households have two cars and don’t use other means of transport, e.g. train or bus. This means many subdivided sections will have to provide four off-road carparks and might mean intensification is not feasible. Is that sensible around public transport hubs? If intensification is going to be encouraged around these hubs, that requirement should be relaxed to also encourage intensification.
Intensification should also be encouraged in new developments. This should be a condition of new developments because many of the benefits of intensification of existing urban areas, especially the social and environmental ones, can come from more intensive new developments. The first stage of Plimmerton Farm is fairly intensive, and PCC should be looking at this as a model for further developments.