As described in our Concept Proposal, during our research we identified a number of different options for houses which could be used to provide affordable housing in Golden Bay. After considering these options we decided for our Phase 1 'Proof-of-Concept' to construct four 60 square metre two-bedroom houses. We are also building a three-bedroom house from the local architect Ecotect and Gibson Timber in Wakefield.
2 Bedroom House Designs
These houses have the thermal envelope constructed using 'Structural Insulated Panels' (SIPs) for the roof, walls and floors. SIPs consist of an outer shell, insulation, and an inner cell. The Formance factory in Christchurch will manufacture the panels and ship them to Golden Bay. We will look at the comparative benefits of having all the wall sections assembled in the factory and shipped up, as well as having individual panels supplied and the walls assembled on site. There are four main benefits from using SIPs panels for the project:
- Excellent heat retention (the SIPS wall panes have R2.8 for the walls and R5.7 for the roof)
- Compared to other building techniques they greatly reduce airflow through the shell. This not only eliminates moisture entering into framing cavities, causing mold and rot, but such air flow also accounts for a huge portion of a home’s energy use and can cause indoor-air-quality problems.
- Improved moisture control. In Golden Bay for a good portion of the year the inside of the home is warmer than the outside; this generates a gentle positive pressure from the inside of the building to the outside. If the inside is not airtight any moisture in the air is carried through the wall assembly towards the outside. When it arrives at the outside of the building and meets the cold surfaces it can condense and cause durability issues.
- Rapid to build. Since the thermal envelope is essentially erected on site--no framing, insulation, etc. to install--they are built very quickly. The chase for all of the wiring is in the panels so it is very quick for the electrician to complete the wiring. With our team building multiple houses of similar designs, we can potentially complete the houses in a matter of a few weeks from the start.
The goal of our 'proof-of-concept' is to test various options, and then sit down with the build team and our suppliers to see how we can most efficiently scale up the efforts for the full roll out of the project.
In terms of the housing options, Goodison have a series of different designs that range from the standard two-bedroom (60 square metre) model, 80 and 88 square metre three-bedroom, to 108 square metre four-bedroom models. We are adapting them to meet our needs, for example with ramps for persons with disability. We have had inputs from the local community (including our local occupational therapist) to ensure that they go beyond the basic accessibility needs for the elderly and persons with disability. This is a major advantage to having Goodison Architecture as part of the team: we can adapt our designs as we need to to meet our community's needs. Below are two examples of preliminary layouts for our two-bedroom and 80 square metre three-bedroom houses. With both we will have the option of 'flipping' the layout based on site needs to maximize the solar benefits.
Here is a video which shows the construction of our first house:
House Designs - Ecotect
Our first three-bedroom house is an Ecotect traditional timber framed design but with a local twist: much of the timber is sourced in Tasman district and milled by Gibson Timber in Wakefield. This is focused on a more 'natural' design and so has features such as timber walls and flooring.
Since some of our houses will be targeted at pensioners and persons with disabilities, we have considered their needs in the project, as well as engaging with people in the community working with those target groups. The Lifemark principles for accessiblity have also been followed where practicable and they have undertaken a review for maximising accessibility.
The Lifemark process is of great value as there are many opportunites to improve the accessibility of a home--and 85% of the improvements were at no or very minor cost. Many of these will be included in our regular houses. An example of one of our accessibility features is the bathroom for our 60 square metre accessible home. Among the features:
- A basin which is wheelchair accessible
- Toilet 450 mm high for ease of access, with large buttons
- Wet shower area 1200 x 1200
The Lifemark features will be incorporated to all of our builds to the extent practicable.
With our goal of building houses quickly and cost effectively we have transitioned from the standard timber piles we used in the first house, to 'Screw Piles' for the second. These allow the foundation to be installed in half a day for about the same cost as timber piles. They also have about 570 kg less embodied CO2 (eCO2) than the concrete solution, so using them for a 60 square metre house is equivalent to saving some 5,500 km of travel for a car. Here they are being installed for House #3.
Here's a video of the installation of a pile at our second house.
One major benefit of our approach is that we minimize construction waste. The average house build produces some 4,500 kg of waste; our first build produced 780 kg. We will continue working towards our goal of waste minimisation as the project progresses.
Another important consideration in selecting the houses to build was maximizing the opportunities to benefit our local community. For example, we expect that ITM will supply materials. Our preference for other suppliers is to purchase New Zealand made if there is not a major cost increase for doing so--for example our windows are manufactured in Nelson; our blinds from Christchurch. With this approach, we have estimated that for every 2-3 houses we build there will potentially be one-person year of employment, much of it in Golden Bay. This is important as our local firms support our local community by facilitating their staff to be our volunteer fire fighters, ambulance officers, etc. Every time we have a local function we reach out to them for sponsorship. Our 'Supporters' page recognizes the help of our various partners with realizing our vision of affordable housing in Golden Bay.
Our houses are being built at a variety of locations around Golden Bay. The map below shows the current status of our Phase 1 houses. The box to the right gives more details as well as photos.
|The Blue icons are completed houses.|
|The Gold icons are houses either being built or in the resource/building consent stage.|
|The Purple icons are sites where the landowners have approached the GBMAHP about the possibility of hosting homes. No assessments have been done as to the viability of participating in the project and it is uncertain how many of these will proceed.|