Sustainable Habitat Construction

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Off Grid Kiwi Bach Retrofit - BACH101 - $15,000

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Off Grid Kiwi Bach Retrofit - BACH101 - $15,000

This modern refit of a classic bach emphasises recycling and a low-energy, do-it-yourself lifestyle to recapture the simple beauty of Kiwi holidays.

Location: Unitec, Auckland
Members: 5
 

Vision for More Sustainable Housing

Sustainability has always been inherent in the typology of the classic Kiwi bach. You design and build it yourself, you reuse found and local materials, and you and your family have a real connection to the place. You also become a kaitiaki or guardian for a piece of our precious coastline. However, with the combined challenges of coastal real estate price rises and the removal of Bachs built on crown land from the 1980s, the true kiwi bach is now certainly an endangered species.


Whats in a name? The name for our SHAC project is derived firstly from the Te Hira Whanau, who through their 93 year old mother/ grandmother / great grandmother hold one of the few remaining live bach leases on Rangitoto Island with the bach identified by its lease number 101. As a tertiary based project ‘Bach 101’ is also a play on ensuring students really came to appreciate bach fundamentals as in this being a foundation bach course.

Quotes

"We had a fun time upgrading the bach - working in the morning and swimming in the afternoon."

"And after we left, the family took DIY to heart and added a small solar electric panel to power LED lighting"

Te Hira Bach 101 Fact Box

• The Te Hira BACH101 Team retrofitted a classic kiwi bach on Rangitoto Island
• The Bach is owned by the Te Hira Whanau with a live lease still in place held by 93 year old Minnie Te Hira Te Hira Bach 101 - Rangitoto Island
• The bach was originally built in 1919 and is now only 1 of 11 remaining bachs in the Islington Bay bach community and 1 of 34 remaining bachs on Rangitoto Island
• Number of Bedrooms: 2
• Number of Students:11
• Number of whanau members involved: 14+
• Number of Professionals and Volunteers: 4
• Estimated Cost: 15,000

The Bach retrofits were finished in 2008. Following the 1 week student lead build, family members completed water tank reinstallation, soffit linings and bird proofing and during the summer the family added a photovoltaic solar panel to provide electricity to run efficient LED lights.

Challenges

The key challenge over the one week build was to manage unforeseen repairs required to the south wall and bedroom floor while trying to maintain progress on the three core areas namely the re roof, re cladding south wall and new composting toilet and generator /energy building.

Seating the Bio-loo composting toilet tank as low as possible into the basalt / lava substrate was a challenge early on in the build with crowbars, sledge hammers and the associated blisters the order of the day!

On discovering rot in the upper wall structure, the team also took the step of replacing all of the bach purlins in order to ensure a minimal 200mm eave. While this took up the best part of a day for four of the team, this intervention was made to minimise the chance of further water ingress and to ensure the longevity of the wall structure.

While all this meant a full on dawn to dusk building schedule we were well pleased to complete all elements to a fully closed in weather proof level in the six day period.

Longer term vision for Bach Sustainability

The Te Hira Whanau Bach 101 represents a beacon of resistance to both the ubiquitous gentrification of kiwi bachs (many claiming bach status but are really urban dwellings located by the sea) and the loss of those built on crown land. With Bach 101, the maintenance of low energy and water use practices and the adoption of appropriate technology solutions like Solar powered LED lighting systems and composting toilets has helped to preserve the essence of Kiwi bach life while enhancing cultural and environmental sustainability.

The opportunity therefore exists for SHaC to help promote more simple, appropriate technology coastal living solutions which seek to maintain, enhance and reclaim sustainable connection to place.

Technical Judging Criteria


As a bach and not being lived in all year round, the Te Hira Whanau Bach 101 brings with it a unique set of technical criteria associated with this occasional and primarily summer use. While attempting to preserve and enhance the historic and cultural elements of this bach, the team have sought to in all technical criteria as follows:

Energy and indoor environmental quality: When at the bach, the entire family’s lifestyle is low-energy. The bach now has a new insulated south wall and ceiling and low-energy solar photovoltaic powered LED lighting system that replaced less efficient candles, lamps and generator powered electric lighting. Eliminating the need for candles and lamps not only reduces the use of fossil fuels, but helps to ensure the sustainability of the bach and the safety of its occupants through eliminating naked flame lighting.

Outdoor cooking in the ‘cave’ maintains a 60 year whanau tradition where an open fire, enclosed by basalt walls and corrugated iron roof, is used to both cook food and keep whanau members warm in the winter months and on cooler evenings. Insulation to the entire roof and south wall has made a major difference to indoor comfort levels. The temperate climate in the Hauraki gulf means that even in winter it is unlikely a heater will now need to be used.

Energy – transportation. As perhaps the closest Bach community to Auckland’s CBD, Rangitoto Island is very ‘green’ holiday location with bach owners able to catch public transport to the Auckland Ferry terminal (Train or Bus) and then take a 20 minute trip on a Fullers Ferry or Reubens water taxi to the Islington Bay wharf on the eastern side of Rangitoto Island. Then with a 5 minute walk to the Bach, the whanau have used public transport, water transportation (more efficient than land based transport) and avoided 2-4 hours trips to either Northland or Coromandel as the most popular local holiday destinations for Aucklanders.

The Bach was originally built in 1919 from native timbers (mainly kauri) and has wall paper on scrim on kauri sarked walls. The floor has sections of 1930’s lino on original kauri tongue and groove floor boards.

Water: Up until the SHaC build the whanau relied on rainwater collected from the bach roof stored in two water tanks of 2000l and 500l respectively. This water is used for all cooking ands washing with drinking water brought in inside 10l plastic containers. A second hand 2500l water tank has been purchased at the cost of $400.00. This tank will be installed on a basalt outcrop up beside the new toilet and generator structure taking water from this roof and acting as a header tank, the base of which sits 3m above the current bach floor level. In this way the water storage has been doubled and with a significant increase in water pressure from the header tank. For cultural reasons (being drawn from a roof used for toilet facilities) it is likely the water from this tank will be used for showering / washing as opposed to cooking.

Due to the unreliable rainfall in the summer months, water use per person will continue to be severely limited with tank levels monitored regularly. Over the summer months the whanau will assess water issues acknowledging both the increased amount of water storage available as well as the increased water pressure. From this experience water use protocols will be set and water saving measures implemented. Despite this the comparatively small amount of water storage ensures a real water conservation ethic amongst the whanau. This water consciousness also assists with minimising the amount of grey water created.

Materials: The materials used for the above 3 projects have been listed previously however a summary of their origin, durability and renewable / reuseable /recyclable resource nature is listed below:

Timber: Recycled native purlin timber reused for toilet roof purlins. Other sound native timber stored under bach for future projects. Rotten timber burnt in open fire for cooking. New H1.2 pinus radiata framing and purlin timber purchased at discounted
and sourced from renewable NZ forests. Boric treatment will ensure the timber lasts for at least 50 years in the capacities used.

H5 piles for the composting toilet shed are chosen for their durability and again are sourced from renewable pinus radiate NZ forests.

Insulation: Autex greenstuf insulation was chosen as it is locally made (Rosebank Rd, Avondale), low irritant being polyester, is reuseable if ever removed from the bach and was offered to us at a highly discounted rate.

Bioloo: The bioloo tank is designed and molded in New Zealand (Rotorua based) The composting toilet system complies with or are better than New Zealand standards AS/NZS 1546.2.2001 and are made in conjunction with AS/NZS 1547. This means they also meet clauses B1 ( Structure), B2( Durability) , G1 ( Personal hygiene) , G 14 ( Industrial liquid waste) of the New Zealand building code. The commercial size of the Bioloo is designed to acknowledge the realities of summer bach life with up to 40 people using the toilet per day. The commercial Bio-loo composting toilet tank is made from Polyethylene and represents a very durable long term solution to dealing with human waste.

Corrugated Colorsteel: Colorsteel Max is manufactured at Glenbrook south Auckland and made from NZ iron sands. Colorsteel max is designed for coastal climates and is powdercoated to extend its life. The project requires that the bach roof maintain its original look hence the need to match the original corrugated iron profile. The roofing material is the most durable corrugated iron product available and is re-useable and recyclable.

Window and door joinery: Windows and doors for the south wall and toilet / energy shed have been procured from a bunker on nearby Motutapu island. The bunkers were created for artillery shell storage prior to WW2 and have been used since the 1970s for the storage of joinery and furniture items salvaged from the demolition of Rangitoto bachs. The reuse of these items for the Te Hira bach is hence very appropriate with students able to walk 200m to the bunkers to select the items before returning to restore/ repair, paint and install the items.

Team Goals: To Source local, durable materials

The Bach was constructed and retrofitted using many found, recycled and sustainable building materials. 12mm Marine Ply wood was selected for the south wall reclad and new composting toilet enclosure and R3.2 Autex Polyester Batts for wall and roof insulation. The new composting toilet and alternative energy shed was built with H1.2 boric treated radiata pine framing and recycled rimu rafters (removed from the bach 101 eastern lean to roof). The roofing iron for the new toilet / energy shed was also recycled from the eastern lean to roof. The commercial Bio-loo composting toilet tank is made from Polyethylene and represents a very durable long term solution to dealing with human waste.

Waste: Students were required to quantify the waste from all of the materials brought to the island and removed from the bach. Reuse of materials reduces waste. This approach included recycled timber joinery windows (from previously demolished Rangitoto bachs) and recycled corrugated iron for the roof of the toilet and generator shed. All rotten timbers were cut up for dry firewood (to be used for cooking in the cave). All sound timbers of over 600mm were stacked under the bach for later reuse / bach repairs.

The following is a summary of waste issues arising from the Building exercise undertaken to date:

Timber: H5 timber pile off cuts reused as ramp stringers, short piles H1.2 off cuts reused for nogs, anything over 600mm stored under bach for future use, short lengths to be burned in open fire for heating / cooking. All native timber removed from bach recycled or burnt if rotten. Insulation and peat moss packaging: Plastic wrapping disposed of in plastic rubbish bags and returned to mainland. Cardboard boxes: For nails, Bioloo components etc..burned in fire. Empty silicon tubes disposed of in plastic rubbish bags and returned to mainland. Timber pellet reused as landing step for toilet. Dunnage stored under bach for later reuse.

Affordable and Suitable for Purpose:
Built in large part by the family, the bach is inherently well-suited and adaptable. The front and rear lean to sections of the bach were built by the Te Hira whanau and are clad in 1950’s fibrolite with a mixture of recycled timber and aluminium joinery elements.

Supporting a Sustainable Community: Bach life on Rangitoto island is critically endangered. The project is essentially concerned with the social and cultural sustainability of the Te Hira Whanau on the Island. The whanau are one of the last groups to have a living Lessee - Minnie Te Hira who is now 93 years old. The restoration and installation of new systems will hopefully allow for many more generations of the Te Hira whanau to maintain connection to the bach, the remnant Islington Bay community and Rangitoto Island.

Transportation to the Island is by Fullers Ferry or by Rebens Water Taxi’s. 90% of trips to the island are on scheduled runs so very few additional trips are made to the island than those going there anyway. In this way fossil fuel use for transportation to and from the island is minimised.

As a humble dwelling occupied in the summer months virtually full time with occasional weekend stays in the spring, autumn and winter, the bach renovation represents an inexpensive set of interventions to increase comfort and safety levels (ceiling and south
wall insulation plus eliminating naked flame lighting) while providing a high quality environmentally sustainable composting toilet capable of handling high summer loadings.

HERS Rating: Paul Stock was commissioned to give the completed Bach a HERS rating. The HERs rating given was 2 which is consistent with a 1970s habitable dwelling. The fact that the Bach was built in 1919, is not lived in year round and encourages connecting with the outdoor environment (as opposed to a modern cocoon) means that the HERS rating is not as relevant for this project. Heating energy load is 227 x 60 = 13,620MJ annum. As noted by Paul Stock “A limitation of the Accurate program is that it assumes that the house is occupied year round - yet bachs and holiday houses aren't so the results need to be considered with this in mind.”

OVERVIEW OF PROGRESS AND CHALLENGES TO DATE:

With a very concentrated student research, design and construction phase (7 weeks from 20 July to 7 September) we were well pleased with what was achieved following the 6 day build / renovation project. This was especially given challenges of transporting most materials to the island by boat. While we had anticipated a second / follow up construction visit, the positives of not returning was that the whanau took over the remaining core elements themselves, in particular the installation of the storage shed wall,
rainwater plumbing, soffit linings and solar photovoltaic lighting system. Given that true bachs rely on continual owner improvements, this was an important and highly appropriate outcome.

As part of the research and design phase students researched a range of interventions for the bach and presented thesed to the whanau for feedback. While all of the resaearch streams were seen as valuable, several were not pursued either because they were seen as out of keeping with the basic bach experience, were too expensive or presented other potential problems as follows:

Wood stove: Students researched a period reconditioned Wood stove with wetback and while this was seen as a good way to return to an earlier era when there was a functional wood stove operating, the whanau were concerned about the potential for a bach fire, now preferring the outdoor cave cooking with its inherent basalt rock surround as a very safe open fire option.

Photovoltaic power system: Students researched a full photovoltaic power system to be housed in the new composting toilet / generator shed. While this was appealing to some whanau members, on further reflection there was a strong desire to maintain a real basic bach experience similar to that which they had as children - the older generation didn’t want to give the teenagers any opportunity to bring their mobile phones and computer games to the island!

Shower platform: A shower fed by the new water tank (heated by wetback and solar panel) was proposed to be located on a platform with privacy screen to the north wall however, issues of maintaining privacy and a concern for water use ruled this out
with the whanau opting to maintain solar showers as a simple means of controlling water use.

French doors to north wall: A key proposal was to add some french doors to the north wall of the bach to open up the living / dining area. Due to restrictions on alterations to the bach from DOC this intervention was reluictantly abandoned by the whanau.

TEAM FINDINGS

The key findings of our project team:

Among the many learnings derived from this project, perhaps the over riding finding was that here, environmental sustainability issues were inextricably connected to the less commonly understood issues of cultural sustainability – the sustainabiltiy of the unique Rangitoto bach typology and a whanau connection to the bach and its wider environs. As the only Maori whanau to have a bach on Rangitoto Island what we have tried to faithfully preserve is a unique Maori response to bach living on the island.

Notion of cultural sustainability. This involves connection to place, building of whanau traditions, ability for future generations of the Te Hira Whanau to have an authentic Maori / bach experience. The uniquely Maori dimensions to their bach tenure revolve around outdoor cooking (Kauta), dealing with larger whanau gatherings over summer (up to 40 at some times) and the reliance on kaimoana as a means of feeding the whanau as well as maintaining connection to the marine environment. The Te Hira whaanu take their role as kaitiaki very seriously extending this role to caring for the island, caring for visitors and daytripper in need and as a strong advocacy voice for RIBCA.

Sustainability of the cave / kauta as a Maori cooking and social institution – the only permitted open fire allowed on Rangitoto island – allows for important social / whanau dynamics to be maintained – a place where the ‘problems of the world’ can be solved
on a nightly basis.

Notion of the sustainability of the Rangitoto bach typology – the Rangitoto bach typology is threatenned through Doc desire to rid the island of private bachs, the Rangitoto Island Historic Conservation Trust (RIHCT) which while undertaking valuable restoration work on many of the bachs, is unitentionally locking the bachs in time and removing the organic owner / bach relationship which is embedded in the process of ongoing modifications ie. A bach is never finished – it is an eternal work in progress!

The value of working with the client as opposed to working for the client. Up to 7 whanau members were working with the 10 student team at any given time. Whanau members also catered 3 plus meals a day for the entire team - this enabled 10 hours a day plus to be spent on the building site.

The value of a concentrated build exercise where team dynamics and project momentum can be built to a high level.

Advice for others:
1. Take care to establish strong working relationships with the kaitiaki / whanau / family group
2. Take care to consider what aspects of a bach are essential to preserving its essence
3. Consider wider notions of cultural sustainability, thinking beyond the actual bach
4. In retrofitting, allow for future modifications so the bach may continue to evolve organically over time
5. Ensure the client / family are as closely involved in the build process as possible
6. Allow for design decisions to be made in ’real time’

TEAM MEMBER COMMENTS


"A bach hopes to be a permanent structure. It’s occupants only temporary whom come and go constantly evolving over time, then so does their place. The historical concept of contributing some addition to a space with unconsciously realising the connection they've established with their unknown future. The bach encompasses a different quality of life
that can be experienced. It signifies solitude freedom and peacefulness."

Students quotes:
"Taking the project through from initial designing stages, getting quotes, ordering the materials and taking part in the physical build gave this project an exclusive element of reality that we don't usually get to learn at university."

“Taking part in this project from start to finish taught me how important the initial meetings and planning stages were during the design stage to ensure that we achieved our goals during the building stage.”

“Meeting with real clients and working alongside real builders on site is the real life experience that we need at university.”

“Living in a historic bach whilst working on Bach101 made me appreciate why the survival of the Rangitoto baches are essential.”

Client quotes:
Ngaire Te Hira (snr)
“My personal view on the project I think the team done a great job and we have good results to show a positive outcome and a big congratulations to the input of the team and those Whanau members who helped out.”

Miriam Scanlan
“Highlights for me personally have been the respect and commitment you have shown to our Whanau especially under the sometimes difficult circumstances. We could not have completed the work ourselves and I am thankful for the opportunity that was given to us to partner with Design Tribe and Unitec on the SHAC Challenge.”

More Information

* TE HIRA BACH 101 FINAL REPORT (.pdf)

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