Renewable Energy and Environmental Awareness Built into a Home

By Chad Farrell and Hannah Munger of Encore Redevelopment, April 2009

The Great Barrier Island is located northeast of Auckland, New Zealand. This island is particularly unique in this beautiful part of the world because there are no municipal water supply, wastewater disposal or electrical supplies for residents of the island.  Approximately 1,000 people live on the island year round, finding ways to survive without these seemingly necessary utilities. The lack of these communal utilities and services means that each home must be entirely self-sufficient.  These distinctive and simplistic homes are called “bachs,” pronounced “batches,” as they were traditionally designed for bachelors.  The word has been appropriated across Kiwi culture to refer to any kind of vacation home in the country.

The featured article in the March 2009 edition of Dwell magazine focuses on South African architects Lance and Nicola Herbst and their story of reinventing bachs on Great Barrier Island.  These houses are quite eccentric, yet they are also highly efficient and effective.  The floor plan is modest and epitomizes the notion of “less is more.”  There isn’t an elaborate front door; in fact, the main entrance to the house is just a few stairs up to the covered terrace that serves as their dining room.  The rest of the floor plan includes one bathroom, two bedrooms, a kitchen, and a living room—all of compact proportions. 

The roof serves as both the home’s water collection system and electricity system.  The electricity is provided by four 150-watt solar panels. The demand for electricity is minimized by creative approaches including use of targeted task lighting, low energy appliances, preference for low-lit ambiance lighting, which, “diverts attention to the night sky.”(1)  Moreover, the use of candles and Coleman lanterns, which “are rituals associated with camping and traditional bachs, many of which relied totally on candles for light,” are utilized in the house as well. 

The water collection system used in the bachs is quite common in rural parts of New Zealand and is similar to rooftop systems in other remote locations such as Bermuda.  The roof successfully captures and stores the relatively limited 1,240 mm (48 in) of rainfall that this northern area of New Zealand receives on average each year.  The rainwater is drained from the disinfected catchment area on the roof into a channel, run through natural leaf filters and into a 6,000-gallon buried concrete tank located adjacent to the house. A 240-volt pump fueled by the roof’s solar panels transports water from the tank into the house.

Wastewater is collected in the onsite septic tank and treated with natural anaerobic bacteria.  Similar to traditional septic systems found in the US, water effluent is released into a drainage field with channels and perforated hoses buried in the lawn, where the nutrient-rich effluent serves as a fertilizer, keeping the grass and plants healthy and green — just like the house itself. 

Bachs are not only good for the earth, but also for the people who inhabit them. By creating a home that is self-sufficient and environmentally sound, the homeowners become so as well.

Note: For more information on the aforementioned process of rainwater harvesting, visit the following websites: http://www.harvestingrainwater.com and http://www.greywaterguerillas.com

(1) Hansen, Jeremy. “Bach to Basics.” Dwell Mar. 2009: 60-64.