Te Whare Kura Building Insights - Practical Facts

The Tūhoe project team members that managed the Te Kura Whare build project, offer up some of their insights learnt while working on Aotearoa's most sustainable building. The team is especially chuffed of the fact that the building  not connected to the utility network at all, which is handy at the end of the month as their is no power bill!

Water Supply

All potable (drinking water) and non-potable water use within the building will be sourced from rainwater collection off the roof. 2 x 25,000 litre concrete rainwater collection tanks are provided which store an estimated 30 days of water for the building. The potable water supply to the building is cleaned with filters and UV disinfection prior to reticulation within the building. Non potable water is provided to toilets.

There is a modest irrigation system for some landscape areas. This system is fed from the existing bore on site.

Fire Protection

The building has sprinklers fitted through out to protect it, life and the contents the sprinkler system is served by a dedicated above ground fire water tank. Water is sourced again from rainwater collection.

Storm water system

All storm water discharge is managed within the property boundary using engineer designed soakage holes. There is no run off onto adjacent properties. In addition provision is made within the landscape to capture excess storm water from major events and overflows; such as a 1 in 100yr storm.  The finished floor level of the building is elevated above the surrounding finished ground level (by 650mm) to avoid potential flood damage.

Wastewater treatment plant

All black water (waste water) from toilets and other sanitary fixtures is treated on site. There is a ’traditional’ septic processing tank for primary treatment, then effluent is held in a holding tank before being pumped to a passive wetland waste treatment system. This wetland is essentially bunded gravel beds, planted with appropriate flora through which the semi treated water flows and which removes nutrients and bacteria from the water. There will be no sewer connection to the Council utility system. This system has been approved by the Regional Council. 

The system comprises 4 main parts:

• 2 x 22,500 litre Sceptic tanks complete with pump
• First stage treatment – 2 No. sedimentation basins
• Second stage treatment – wetland filter basin.
• Dispersal of treated water via sub-terrain dispersal field

Maintenance and operational requirements will include; a manual changeover of the primary discharge pipe to alternate discharge into one of two sedimentation filter basins. This needs to be done every 10 days to two weeks. In the event of a large event, it is recommended that the primary discharge pipe is manually adjusted to enable discharge into both primary treatment tanks simultaneously. Wetlands require bi annual weeding and plant maintenance like any working landscape

A separate grease trap is provided to the kitchen waste outlet and this will need maintaining approximately once per month dependent on usage patterns.

Electricity

The building is designed to be very energy efficient and will generate its own power using a very large 580m2 roof mounted solar photovoltaic array to generate electricity. The power generated by the panels will feed into the main distribution for the building.

The building is connected to the ‘grid’ (utility network). There is a feed out and a separate feed in meter to allow energy to be billed correctly. This means that when the solar power array on the roof is generating more power than is being consumed within the building, the excess electricity will be fed back into the power utility grid in the street. However, during winter months, when the roof mounted solar array cannot generate enough power for the demand within the building, the building will draw electricity from the street utility network.

It is anticipated that the amount of energy exported to the grid over the course of one year will equal the amount of energy needing to be imported. This is called “Net Zero Energy”.

A battery backup system is to be provided to maintain power to the Archival environmental control equipment during power outages. The key components of the system are;

• Roof mounted solar (photovoltaic) panels
• Solar (PV) distribution and metering
• Back up battery system

Hot water

To generate hot water, the building has a 15m2 flat plate solar collector on the roof which supplies and stores heat in a 1000litre hot water cylinder. Hot water is reticulated to the kitchen, showers and toilets. The solar collector system uses a simple ‘closed loop drain back’ technology which protects the collector and cylinder from overheating, frost damage and power failure. The backup hot water is provided by 4 x 5kw electric elements position at the top of the 1000litre cylinder.

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