Case study: Chatham Islands sustainability
The Department of Conservation (DOC) has made a number of changes to reduce its energy use on the Chatham Islands.
Chatham Islands
Energy efficiency and renewable energy programme
Getting results
Graph of potential cost savings
Other benefits
The new staff units showing the double
glazing and solar hot water systems
Chatham Islands
The Chatham Islands are the most remote of New Zealand, lying almost 750 km from the mainland. Following an energy audit by Right House in 2009, the cost of diesel-generated electricity for DOC use on the islands was estimated to be five times that of electricity on mainland New Zealand. Drastic change was needed.
Energy efficiency and renewable energy programme
In May 2009, DOC installed a 5.8 kW photovoltaic (PV) solar electricity generation system. The system is integrated into the local Chatham Islands Council grid and supplies electricity to the rest of the island.
Denny Prendeville packing old batteries
into old freezers for shipping to the
mainland
Various energy efficiency upgrades were also installed in DOC buildings and staff houses to support the PV system, including insulation, hot water cylinder wraps, thermal curtains, draught proofing, energy-efficient light bulbs, old fridges, freezers and heat pumps were replaced. Old appliances were sent back to the mainland for recycling.
DOC also took the opportunity to incorporate energy-efficiency measures-such as LED lighting, energy-efficient appliances, wetback woodburner heating and solar hot water heating-into the design and build of four new staff flats.
Getting results
View a graph that shows the estimated savings in electricity costs on the Chatham Islands
Before May 2009, the DOC Chatham Island Area Office consumed an estimated 20,320 kWh of electricity per year at $0.98/kWh, a total cost of approximately $19,913 per year. Since then, energy-efficiency measures have resulted in a 71% reduction in the cost of producing power by diesel.
- The solar hot water heaters are estimated to have reduced annual energy use by 9,770 kWh, saving an estimated $9,580.
- The 5.83 kW ground-mounted PV system is estimated to produce around 7,404 kWh of electricity per year.
- The efficiency measures, coupled with the installation of the PV system, are estimated to reduce the annual electricity costs to $5,156 per year, a saving of 74%.
Photovoltaic panels on Chatham Island
Other benefits
Having the PV system connected to the local grid enables DOC to contribute electricity to the rest of the island after hours, on particularly sunny days, or at weekends when DOC staff are not using it. An energy agreement between DOC and the Chatham Island Enterprise Trust (CIET) allows DOC to sell excess power back to CIET at half the current retail price. This takes the form of a rebate on the monthly energy bill.*
There have also been unanticipated benefits from the energy upgrade; happier, healthier staff and their families as a result of lower energy costs to them and less maintenance to buildings required.
Graph of potential cost savings
Graph showing potential cost savings over a 12-month period on electricity
bills at the Chatham Islands Area Office
The graph shows the estimated savings in electricity costs on the Chatham Islands. (Please note this should be treated as a guide only.)
* Electricity generated that directly offsets electricity purchased from the grid will save the full $0.98/kWh, while electricity generated that is not consumed onsite will be fed back into the island network grid for a credit of $0.49/kWh. The savings from the installation of the PV system is estimated at $5,180 per year ($3,103 due to direct electricity generation and $2,076 due to grid credits).
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