Frank Dallmeyer - frank@tropicalenergysolutions.com.au - 07 4772 7394
A) The 21st Century City Cottage Project, or
B) The story of the tropical TRIPLE ZERO HOME in Townsville
Background & Introduction
A broad range of issues affect the suitability and sustainability of our homes in the tropics. These include:
- high construction costs
- high operating costs; especially for energy, rates and insurances
- limited land availability
- oversized house designs
- lack of tropical design capabilities
- need to adapt to and mitigate climate change
Addressing all these issues at once appears to be very ambitious but once we looked at the relationship between
these issues we thought we should "give it a go"
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In 2012 we made the decision to demonstrate our ideas and concepts by building a new residential property on the
fringe of the Townsville CBD. We owned a 300m2 block of land that was zoned for commercial and/or residential
activities and our original plan to establish our offices on this site proved to be too difficult, mainly due to the
building codes and local council requirements.
We knew that none of the house plans offered by local builders would suit the small block and our ideas of
comfortable living in the tropics. The first step was therefore to find a builder who was interested in a cooperation to
develop a design that was innovative but also affordable at the same time. To build something that is energy
efficient, comfortable and sustainable is not difficult if you have unlimited funds, but we wanted to demonstrate
that it could be done at the same cost that is charged for a typical new subdivision property and we wanted to avoid
overcapitalizing on this property.
Being involved with the local business community for some time helped us to establish a relationship with Finlay
Homes for this project. It turned out to be a 15 month journey from the early design studies to the completion of the
building, but it was a journey worth doing.
We are now enjoying a property that is very user friendly, low on operational expenses and easy to maintain. But it is
also pleasing to the eye, fits into the neighbourhood and it has an operational carbon footprint of zero.
Let's see how this was achieved:
1. Design & Layout
2. Materials
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3. Appliances & Equipment
4. Procedures
5. Results & Key Project Parameters
Design & Layout
Having an empty, flat block is great, but if it is only 10m wide and 30m long your design options are quite limited.
Our block also shared a driveway (easement) with the neighbouring block that had to be maintained.
We started with the design from the inside by defining the areas and amenities needed by either a couple or a
couple with one child. A good sized bathroom with a separate toilet and a reasonable large kitchen were placed in
the centre of the building and close to each other to minimise plumbing expenses. The living areas and the
bedrooms are at opposite ends of the building, separated by the amenities. This minimises the need for "traffic
areas", offers easy access and noise separation.
The kitchen is separate to the living areas and has access to an outdoor service area or "wet kitchen". It isolates the
internal heat loads from cooking and refrigeration, the noise from appliances (do you like the sound of a grain mill or
dishwasher?) and the smells from cooking. It also allowed us to design the kitchen as a workspace rather than as a
shiny part of the living area.
Both bedrooms were sized for a double king sized bed and built-in wardrobes.....but not much else. This makes it
more energy efficient to air-condition these areas during hot summer nights. Both bedrooms are equipped with
generous louvers on two sides for effective cross ventilation but the second bedroom has been equipped with more
window surfaces to allow natural light harvesting for its alternative use as a home office.
A hallway acts like a "spine" for the building and flows into the living area of almost 50m2. It also serves as a corridor
for airflow and light. Because it occupies the section with the highest ceiling louvers could be installed above the
front door. They are protected by a roof overhang and could be left open in all weather conditions and without
creating a security issue. Equally louvers are installed at the other end of the building above four sets of french
doors. Together they offer many options to control the airflow and ventilation across the building.
Cathedral ceilings up to 4.2m high were selected because they create volume and a spacious feeling. They also
facilitate the effective use of ceiling fans and indirect lighting systems.
Finding space for storage areas is a challenge in smaller buildings. We identified the opportunity to build two atic
style storage rooms above the laundry, toilet, wardrobe and kitchen cabinet areas.
The rear of the building faces East and is the ideal location for a shaded deck and courtyard. The cathedral ceilings
and ventilation pathways on both sides of the building allow breezes to enter this area. To the front a carport with
another cathedral ceiling was added. The space underneath the ceiling is ideal for the storage of kayaks and surf
boards and a screen to the front will add privacy to the front yard area.
The building was designed from the inside out and with a focus on functionality. We believe it demonstrates the old
engineering sayings that "form follows function" and that a functional design most likely results in a good looking
design, too.
Materials
The material selection is most likely the area with the greatest impact on cost. And this applies to both, the
construction cost and the operational cost. Unfortunately the cheapest construction materials are often those that
have the poorest performance in regards to the efficiency of a building.
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We selected a small volume waffle pod concrete slab for its earth bonding capacity. Its thermal mass is protected
from direct sunlight and helps to create a cool feeling from the floor. In contrast we eliminated all brick, concrete or
other high thermal mass materials from the walls. The light weight timber walls won't store day time heat loads and
their smaller width adds valuable internal space. Reflective sarking and rot resistant composite cladding materials
support the sustainable design by providing durability and longevity.
In tropical conditions roofs and windows are the greatest concern for external heat gains. A composite sandwich
roofing panel with the thickest available insulation was chosen for its many advantages over traditional roof cladding
materials. Its rigidity allows long spans and true cathedral ceilings. It also minimises the risk of damage from cyclonic
wind loads. Unlike most bulk insulation materials the sandwich panels can't absorb humidity, thereby avoiding the
loss of its insulation capacity over its entire lifetime. A brilliant noise insulation capacity is another benefit. Last-butnot least the thicker gauge external sheeting gives a solid foundation for the installation of rooftop PV solar modules.
The timber frame, the composite cladding and bamboo flooring boards are all made from low grade timber and
fibres that have a small embedded energy content and are considered a carbon emission sink or store.
Louver windows with tinted "low-e" glass reflect most of the sun's heat radiation. Unlike sliding windows they can
open to nearly 100% of their coverage to provide valuable natural ventilation. Some windows/louvers are positioned
high to aid privacy and security while others are starting at the floor for additional air circulation.
Traffic areas in the hallway, kitchen and bathroom are tiled with pebbles. This creates hard wearing surfaces and a
cool (x2) feeling. The outdoor living area is using an "Ecodeck" floor in light grey colour. It contain approx. 50%
recycled plastic bottles and 50% bamboo fibres, making it resistant to rot, termites and fire. No paints or oils are
required for its lifetime. The light colour was chosen to allow natural light reflection into the indoor living area and to
avoid heat absorption into the material.
A similar approach was used in the selection of the concrete walkways, drive ways and service areas. A 90/10 "salt &
pepper" aggregate includes 90% white pebbles and only 10% dark pebbles for reduced heat absorption and
additional light reflection.
Appliances & Equipment
Minimising the need or power consumption of air conditioning equipment makes good financial sense in the tropics.
The comfort of the occupants shall not be compromised and eliminating appliances was not an option. Consequently
the house is equipped with a complete set of kitchen tools and facilities, large TV and entertainment system, a few
computers and the usual household appliances.
By using energy efficient appliances, e.g. induction cooktop or LED TV set we added upfront cost but gained lower
operational expenses. The same approach was taken for all light fittings (mainly LED, some with timer or dimmer)
and the ceiling fans. Six "Aeratron" fans were installed because of their aerodynamic design and super efficient
motors. At maximum speed they consume only 1/3 of the power consumption in a traditional ceiling fan. Moving air
without buffeting and with minimal noise is another valuable feature.
Because all power consumed in a building creates internal heat loads it makes good sense to invest in efficient
appliances. Savings are then possible by installing smaller air conditioning units. Our house is equipped with three
2.5kW cooling capacity split systems. They are the latest models from Daikin with an incredible 7 Star rating, many
innovative features and an environmentally friendly new refrigerant (R32). If all three units are running at maximum
power their combined consumption is only 1,300W, less than your average toaster or hair dryer.
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The optimised power consumption made it easy to design a cost effective PV solar power system. We decided to
demonstrate the capabilities of our Triple Zero Power System® in our own home. It uses no other power source than
the sun and a medium size battery storage system to provide a generous power supply 24/7 and all year round.
Zero electricity bills, zero gas bills and zero emissions take away any worries of future price rises or grid black-outs.
The roof is equipped with a generous size PV solar array (26 panels) and the batteries are completely sealed and
maintenance free. They are oversized, too, meaning they are treated gently for a lifetime in excess of 10 years.
The system is controlled by the latest stand-alone inverter technology in a redundant design. Using two system
inverters and two battery banks mean that a component failure can only reduce the system capacity but it won't
result in complete power loss.
To add further capabilities we installed a C-BUS home automation system for the entire power distribution in the
house. It allows us to manage and shift electrical consumption to make best use of the free solar power during
daylight hours.
Procedures
Knowing that we have excess power available during the afternoon hours allowed us to save some money by
installing a standard 80L electric hot water system. It is charged every day during the afternoon only and acts as
another energy storage device.
On sunny days with fully charged batteries the solar system will instruct the C-BUS controller to switch on the air
conditioning system during late afternoon hours. The available solar power will be used to cool down the building.
By the time the batteries have to carry the load the air conditioning system is in "cruising mode" and only has to
maintain the target temperature.
Additional control circuits are used to pump water into a header tank during daylight hours. After sunset the trickle
irrigation system is then activated and operated by gravity rather than an electric pump.
The carport has been equipped with a large capacity power outlet that allows electric vehicle charging up to 16A. At
present we work on a classic car conversion to use this feature.....
In really demanding conditions we can use the load shedding function of the control system. Our fridge/freezer
could maintain its temperature overnight without power supply, so once the batteries are reaching a point where
savings are needed, the fridge/freezer is disconnected until the morning sun provides addition power supply.
Results & Key System Parameter
After just four weeks of operation we have only limited data and experiences, but at this time of the year the solar
power yields are at their lowest in Townsville and approximately two hours less daylight are available at the times
when it matters most - during breakfast and dinner times. Our system has "never missed a beat" so far and the solar
supply and the storage capacity have proven to be very generous.
The summer time will reveal the buildings performance in other areas, in particular its heat reflection and ventilation
capacity. Landscaping is still in progress and will make the home even more liveable.
The layout and sizing of all rooms is working really well for a couple and the small house is big on entertaining space
when needed.
Opting for a smaller building footprint but higher quality materials gives the house a modern and innovative
appearance. Everyone should judge its looks for themselves..........our own verdict is simple: we love it!
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Block Size:
300m2
Building Size:
140m2
Internal Size:
100m2
Garden Size:
160m2
PV Solar Capacity:
6.5kWp
Battery Capacity:
33kWh (nominal), 10kWh (effective)
Weight of Batteries:
1,200kg
Day Time Power Output:
4.4 to 12.5kW
Night Time Power Output:
4.4 to 7.5kW
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