When we started the ZEH project one of the challenges we foresaw was with the consenting of the low impact building techniques and technologies that we wanted to implement. Many aspects of the house will differ from the conventional approach of building.
A report1 by Beacon Pathway and e Cubed Building Workshop in 2006 looking at Auckland City Council policies and procedures identifies the barriers to sustainable building which are common to many Councils. These included:
- Lack of information on sustainable building practices
- Sustainable approaches to building are not included in acceptable solutions to the building code and therefore require approval through the more time consuming and expensive route of "alternative solutions"
Specifically some issues were identified in relation to the Health Act were identified:
....but the guidance it provides around ensuring wholesome water appears to be creating an implementation barrier to rainwater and greywater re-use.
We have identified this barrier in the Auckland Regional Council (ARC) District plan this week. The guidance it gives appears to exclude the greywater technology that we wish to use.
We have had preliminary discussions with both the Auckland City Council and ARC, who have been very supportive of what we want to achieve. It appears that the technology that we are propose to use for grey water irrigation of the garden does not pose any health risk but is unintentionally caught in the planning guidelines.
We recognise the important role that councils play in ensuring health and robust homes and we are looking forward to working with them to reduce the barriers to the use of low impact approaches and technologies. The ideal out come would be that future building projects find it less difficult to obtain consents.
Many of these technologies have benefits to the home owner, but also to the Council and wider community. Greywater reuse and rainwater use are two such examples. One of the benefits of using greywater to irrigate your garden is that it reduces the total volume of water used and also reduces the peak summer time water demand on the municipal supply. If implemented on a large scale this could reduce the requirements of the water supply and waste water removal systems therefore reducing the size of infrastructure needed to serve our homes.
Rainwater harvesting can be similarly beneficial. Impermeable building surfaces inhibit the natural drainage of rainwater into the ground and so increase the volume flow rate of stormwater from a site. Increased stormwater flow can cause erosion to local waterways and damage to the surrounding ecosystems. Surface run-off from buildings and roads, etc often contains potentially harmful chemicals which, as stormwater is often left untreated, end up in the local waterways. Collecting water from impermeable surfaces (typically the building roof is most practical in an urban environment) reduces peak stormwater flows and minimises emissions from a site. The rainwater is filtered and can be used in the home (typically for toilet flushing and laundry) or for outdoor uses resulting in lower volume flow rates from the site and the diversion of a proportion to the wastewater system rather than the stormwater system.