The Haven 2
Key Facts
• Best example of an affordable tropical sustainable home in 2014
• Passive design works with renewable energy to make it carbon neutral
Project Data
Location: Redlynch, Cairns
Year Completed: 2012
Project Cost: $265,000 with no ongoing power bills
OVERVIEW
The brief for this home was to create an affordable sustainable home for the project home market. Members of the Tropical Green Building Network in conjunction with a builder/project manager and building designer worked with local suppliers to showcase sustainable materials and create a home to educate the public on sustainable design and building. This home is a viable affordable building alternative with a total cost of $265,000 with no ongoing power bills.
The home has won local, state and national building and design awards including HIA GreenSmart National Display Home of the Year 2013 and National Built Environment Design Institute (BEDI) Most Sustainable New Home 2012.
The home features sustainable materials, many of which have been sourced locally, and materials made from recycled products. It also incorporates energy efficiency features and water saving devices. It is also a lifetime home, which means it is accessible for occupants with a mobility disability and flexible in use over time if circumstances change.
PLANNING AND MANAGEMENT
The project was designed locally by a designer educated in architecture and sustainability and with tropical design expertise. The builder aligned with these principles and was HIA GreenSmart accredited.
Contractors and suppliers were familiar with the local climate and were made aware of the project brief. As innovative sustainable techniques and materials were proposed, the contractors had to learn these applications.
Suppliers were involved throughout the process to provide product training and expertise. For example James Hardie and Altair Breezeway louvre representatives came out to brief the build team during the construction process.
Waste minimisation and recycling procedures were implemented during construction. Eaves and wall heights and widths were designed to standard sheet sizes where possible minimising waste. All metals were recycled. The composting system was set up at the construction stage for the builders to use during the build.
Construction was programmed to commence at the beginning of the dry season to minimise wet weather impacts and delays.
SITE
The site lies on the Northern side of Redlynch Valley Estate, a unique development which was predominantly dormant cane fields, adjacent to mountains and conservation rainforest at its perimeter to the East, and Freshwater Creek to the West. There are over 900 homes nestled in the valley.
The block is flat and there were no trees on the site. To the rear of the site is a surface water runoff easement which takes the runoff from the mountain to the creek. All building pads are higher than the Q100 levels and the parkland in the estate is designed to act as a sacrificial flood plain if the creek bursts its banks.
The home is a 2 minute walk from the main foot and cycle paths which go around the development, and 5 minutes from the swimming hole and mountain trails. There are 5 schools within 10 minutes drive, and 4 of these have school buses which frequent the Estate. A good sized shopping centre with a doctors’ surgery, food shopping, hairdressers, bank, etc. is within 8 minutes driving distance, as is the nearest hotel/pub.
Minimal earthworks were needed. The site was analysed for greywater use but since it is within 50 metres of a creek system this was not allowed.
DESIGN
The home was designed with passive features to suit the climate, improve user comfort, reduce the need for mechanical ventilation and lower ongoing user costs. The home achieved a 9.5 star energy rating by the use of passive design features such as orientation, insulation, ventilation and material and colour selections.
The orientation of this site was not ideal (long walls face East and West), but in many subdivisions it is not possible to achieve perfect orientation 100% of the time. To mitigate the effects of poor site orientation the home was orientated to capture prevailing breezes, with a narrow building width to maximise cross ventilation and generous eaves for shading. Passive design features were used to create a superbly efficient and comfortable home including use of open plan design and minimising internal walls and hallways which block breeze paths. Also, living areas were predominantly located to the east away from the afternoon western sun and with access to north-easterly and south-easterly breezes.
Natural ventilation was harnessed by a narrow building width for cross ventilation. Louvres and doors were placed in breeze paths with a minimum of two openings in each room to assist in cross ventilation. Louvres and large sliding doors were selected to allow for maximum open-ability and ventilation. The 2.7 metre high ceilings were selected to enhance ventilation and air movement. The 2.3 metre high internal doors promote airflow.
The ventilated roof system including eave vents and a solar roof vent reduces the temperature of the roof. The roof incorporates a shading system including 850mm wide eaves (including gutter) which also provides protection from rainfall.
There is a pergola to the east side to protect the two bedrooms even further from morning and mid-day sun, making use of shading from adjacent structures on the western side.
The construction system has insulated lightweight frames which do not absorb and radiate the heat into the home (unlike concrete block). Although the garage is constructed of concrete block this is the location of the clothes line so radiated heat assists this process. The garage is isolated from the house with an insulated roof and walls so that any heat generated in this space does not transfer into the home.
The home is built on a concrete slab and the design ensures it does not receive direct sunlight to warm it. The thermal mass of concrete slab stores the cooler temperature released by the soil beneath it and the lower temperature can be released in to the home during the day to help keep it cool.
The home is also designed to withstand cyclones as it is located in a C1 wind rating category area.
MATERIALS
Durable, robust and mould resistant materials are selected where possible from local suppliers or Brisbane as this was the closest manufacturing location. This included timber from renewable Forest Stewardship Council accredited sources such as 13mm Ecoboard for internal walls as this is a recycled content plasterboard.
Insulation is installed to all of the walls and roof including sisalation and bulk insulation. Insulation products are articulately specified to suit their location and task including condensation control. The insulation also reduces sound transmission between rooms. Products such as Earthwool batts are chosen as they have no VOC’s and are low irritant and made from recycled glass.
The no VOC paint that is chosen is also made from recycled engine oil. Light reflective colours are selected externally for the roof and walls and light colours are used internally to create a feeling of space and assist with the reflection of sunlight.
The steel roof and tank is selected for durability and steel can be recycled. The concrete slab is used for thermal mass and also ease of access into the building.
All cabinetry is E0 (no VOC) including all carcasses and all building elements are termite resistant.
ENERGY
Passive design maximises natural ventilation and in the hot humid wet season the 1400mm ceiling fans in all rooms (including patio) maintains comfortable temperatures.
Although used rarely, the air conditioners selected were energy efficient models. The house is zoned into air-conditioned areas and the rooms that benefit from air-conditioning have walls and ceilings that are insulated so that air conditioning can be used efficiently.
To further reduce energy demand, LED lighting is installed throughout and energy efficient appliances including an induction cooktop are used.
To service 100% of the electricity demand of this grid connect system, there is a 3kW solar power system with a 5kW inverter for later expansion. The grid connect system has the energy retailer paying 44 cents a kilo watt hour. A 340 Litre solar hot water split system also means free hot water.
WATER
A 5000 litre rainwater tank with appropriate tie downs for the cyclone rating is plumbed into the toilets, laundry and one outside tap.
Aquaclic devices that reduce water flow to taps are also installed in the basins, kitchen and main shower to reduce water consumption.
The Cullector™ shower in the en-suite bathroom recirculates cold water normally wasted while the shower reaches temperature.
A Caroma toilet with a basin over the cistern reuses water for hand washing for flushing.
A selection of native vegetation that also sit in mulched garden beds reduces the need for watering the garden and permeable surfaces encourages onsite water retention
The owners recent water bill was $20 for the quarter.
OWNERS/USERS STATEMENT
This home is a pleasure to live in. It is cool and comfortable year round. The home makes the most of the natural environment with the indoor/outdoor connection. The narrow built form has views from all rooms across the garden and mountains. There is a massive garden space so we can really enjoy living in a suburban area. And the best thing? Having no power bills!
PROJECT TEAM
Base building architect/ designer: Sophie Barrett (Green at Heart)
Interior designer: Client/builder
Structural engineer: CMG Consulting Engineers
Energy efficiency rating consultant: Andrew Barrett (Green at Heart)
Other consultants: HIA Greensmart (Rachel Whymark)
Builder: Kenick Constructions
