INTRODUCTION

This page briefly describes a Passive Solar house situated on Bribie Island , a small island just off the coast 50 kM north of Brisbane, Qld, Australia (Latitude 27 degrees 2 minutes South).

Bribie Island has a sub-tropical environment with a moderate to warm temperature range.  The weather parameters for winter are generally dry, cool nights and warm sunny days,  (9 to 25 deg C) and, when windy, cool southerly prevailing breezes.  For summer, warm north-easterly breezes and a hot, humid, wet season in January/March (25 to 31 deg C).  Yearly rainfall is approximately 1600mm.

This house design, construction and finishing detail description has a mix of present and future tense, as we are continuing work and modifications towards final completion.  Many of the statements made within this document are based on the original design, equipment purchased and installed, current projects and hints of future development. 

BUILDING DESIGN PRINCIPLES

The house is built in two wings with a large cross-connecting entrance foyer.  The major part of the building, the "main wing", on the southern side of the block is basically a single bedroom house designed to maximise winter sun penetration for warmth, and for summer, to provide shade and encourage airflow for cooling.  This separation of the two wings enables us to minimise house cleaning and maintenance.

The "guest wing" (on the northern side of the block) also has passive solar design features but is not as heavily oriented to winter sunshine penetration as the Main Wing  The guest wing comprises two bedrooms, bathroom and laundry.  The guest wing is likely to be mostly unoccupied (except for laundry use) and therefore requires no regular housework or cleaning.

The shed/garage buildings on the western side (away from the canal) provide sufficient room for three cars and a caravan, plus a large workshop area and the renewables energy system plantroom.

The eastern end of the house overlooks a wide canal that cools the summer breezes and provides a great thermal heat sink in winter.

The major passive solar design principles, building strategies and construction practices we adopted are:

• Correct orientation for both maximum solar gain in winter and minimum direct solar penetration in summer.  In addition, the floor plan layout and both internal and external walls are positioned to take advantage of morning and afternoon winter sun angles and penetration, yet exclude morning and late afternoon summer sun penetration.
• Massive thermal inertia in the concrete slab floors and 300mm thick rammed earth walls.
• Selectively placed,  dark colored, floor tiles on thick, concrete slab, in areas irradiated by winter sunlight (to maximise internal thermal energy absorption and storage). 
• Internal blinds can be pulled out of ceiling cavities to cover all glass areas on cool winter nights.  External, computer controlled, motorised blinds with 95% UV blockout on the eastern side windows exclude early morning summer sunlight penetration.
• The northern wall of the Main Wing is floor to 3.0M high ceiling glass for the full length (a total of about 75 sq.m) which, coordinated with the roof overhangs, permits sun rays to shine on the part tiled floor during winter.  This glass wall has approximately 80% of its area capable of being opened for summer breeze control, comprising regularly spaced floor to ceiling louvres to aid in controlled ventilation plus large sliding doors.  The glazing design permits an extensive open environment in the summer period.
• The southern, rammed earth wall has regularly spaced, very tall, narrow (0.3M), timber louvred windows (each approximately 0.75 square metre) to assist in cross-flow ventilation in summer. 
• The clerestory windows along the full length of the roof top of the Main Wing have double glazed, fixed windows and regularly spaced louvres for promoting summer ventilation.  These windows permit winter sun penetration onto the upper section of the southern rammed earth wall for much of the 25 metre length of the main wing of the house.  This enables solar energy to be absorbed (internally in the house) for over 8 hours of a mid-winter's day.
• The clerestory windows, the roof design and roof color selections are an integral part of the thermal air flow design.  The aerodynamic features of the roof line and angles encourage gentle breezes through the house in the summer months.  Additional low-energy (large) slow revving, roof mounted, fan assists ventilation on very hot, windless days
• All roof spaces and (non-rammed earth) walls are heavily insulated with materials selected for reduced thermal conduction, reduced radiation heat transfer and noise absorption.  The roof space is insulated with R1.5, 50mm bulk insulation/reflective foil blanket immediately under the custom-orb roofing, plus R2.5 bulk insulation batts placed on all ceilings.  All hollow (non-rammed earth) walls are filled with R2.5 sound absorbent insulation batts.
• Roof space voids have solar powered extraction fan devices to ensure the roof space remains cool in summer and, when switched off for winter, permits a warm ceiling space in winter to assist in reducing living space heat transfer.
• The floor most used when standing/walking (the kitchen), and also the "relaxing", (sitting) room,  are specially designed Australian Blue Gum timber floors placed on bearers suspended at each end (in a concrete void) to provide a degree of "springiness" to make them comfortable to walk on.  The concrete void beneath these floor boards are filled with sound absorbent insulation batts to make them quiet to walk on. 
• All major 240 volt electrical wiring is positioned as far as possible from frequented living areas and sleeping areas.  No power wiring outlets are positioned near the bedhead to totally eliminate varying, high level, electromagnetic fields adjacent to the bed.  Bedhead lighting is data controlled, remotely  switched, remotely transformed, low voltage system to maintain low electrical energy fields near the bed when the lights are used.
• All bathroom, toilet and kitchen exhaust ventilation is discharged above the roof and not into ceiling space areas.  

WATER MANAGEMENT

The house has sufficient tank water (50,000 litres) to effectively negate the need to import town water supply.  The 1.5 kW pressure pump system is constant flow and powered from the solar system.  Unlimited (solar powered 1.8 kW pump ) bore water is available for gardens, lawns and garden water features.  Town water is connected to the site and is available if required.   A Beasley 330 litre stainless steel, high pressure, thermal solar hot water system with extremely efficient "all copper" panels with selective coating and low-iron glass covers provides hot water.  The HWS is mounted very close to the kitchen and main bathroom (major usage point for frequent hot water supply needs).  The HWS solar panels are tilted at 25 degrees, a compromised  but recommended angle for the house latitude location.  All copper reticulation piping has been oversized in the cold water distribution system and the critical hot water system sections to reduce flow rates to minimize noise and water hammer.

ENERGY SYSTEMS 

The house is designed to be electrically totally self-sufficient with a renewables powered electrical energy system with large storage batteries and is fitted with very efficient household appliances.    However, it is connected to the local Authority (Energex) supply for emergency backup, access to off-peak supply (if required for battery charging, solar hot water system boosting and tumble drying) and an interactive inverter programmed to export all power generated in excess of requirements.  The current "buy-back" rate for electrical energy (we have chosen from the options available) for unlimited exported energy here in Qld is 8 cents/kWH - about 60% of the standard (13.5 cents/kWH) rate users pay for electricity.  Off-peak purchase rate is about 5.4 cents/kWH.

The household electrical requirements are provided by a sophisticated, microprocessor controlled battery/grid tied (Australian made) Power Solutions Australia (PSA) 240 Volt, 5 kW inverter (which has up to 12kW short term peak capability for those heavy workshop loads).  This inverter is a solar/battery/grid interactive sine wave inverter with seamless, fully programmable, energy transfer in both import and export modes and battery charging.  The PSA Inverter also has automatic generator connection control and management.  However, a generator is not needed in our installation due to the emergency availability of the permanent interactive connection with Energex as well as the relatively substantial photovoltaic system and battery storage. 

Innovative electrical reticulation system circuit and control design takes advantage of Energex off-peak rates (rarely, but when required!) for various energy management and energy use functions.  This permits great flexibility on energy control, use, charging, export and cost management.   We expect to pursue modifications to our system to take better advantage of Off-Peak conditions if multiple, time-related tariff  charges and rebates are imposed. 

A reasonably large, 48 volt solar battery system (comprised of eight Century-Yuasa Solar, series connected, 875 ampere hour 6 volt solar batteries weighing 135 kG each, totalling approximately 42,000 watt hours of available energy) enables energy storage from renewables as well as providing storage if emergency charging (programmable for either on-peak and/or off-peak supply from Energex supply) is required.

Battery storage capacity is designed for an estimated two days without renewables input to a 80% depth of discharge level.  Selecting this low depth of discharge parameter ensures a long battery life (expected to be 10 to 15 years).  Due to the fact that we have (currently) elected to stay connected to Energex power, we consider the battery reserve capacity is adequate and as we expect to rarely use battery power, the system is likely to enable an exceptionally long battery life.

Our solar system design estimates are heavily based on the bright, sunny, dry winters experienced at Bribie Island (ie, winter is usually the most taxing time for solar based energy systems as a result of fewer hours of sunlight, but our bright, generally rain-free, sunny winters helps to alleviate this) and the fact that we have a permanent, controlled connection to Energex.  We also have the ability to access Energex supply for battery charging (either with on-peak or off-peak rates) if required.  This convenient Energex backup arrangement can be manually controlled or fully automated based on energy withdrawal from the battery system.  Of course, being a seamless, integrated battery operated system means the whole household is on a very effective, uninterruptible power supply (UPS).  Already we have witnessed our neighbours suffering from (the ever more frequent) electrical blackouts, and it has been a most satisfying feeling watching their dilemma while we live normally with our uninterrupted, high quality power system. 

The solar photovoltaic array comprises 48 panels, totalling 3.072 kW, of the latest, high technology, Unisolar triple-junction, 64 watt amorphous panels.  This panel system is capable of supplying up to a theoretical maximum of about 18 kWH per day however we rarely experience more than 17kWH per day in practice.  Average production is about 13.1 kWH per day.

The Unisolar triple-junction amorphous panels, in contradistinction to the older technology poly-crystalline and mono-crystalline panels,  exhibit excellent shade tolerance, are hail resistant, and have a substantially increased efficiency when hot (particularly important in a warm climate such as experienced on Bribie).  The 48 photovoltaic panels, mounted in 12 light, aluminium array frames, each comprising 4 panels, are hinged to allow quarterly adjustment to improve seasonal solar energy absorption efficiency.  Each six panels are series wired for a nominal output of 72 Volts, and the 8 groups of panels are parallel fed into an Outback MX-60  Maximum Power Point Tracker Regulator with a programmed output at 48 volts.  The Unisolar panels have a 20 year guarantee (which essentially means an unlimited life) thus equipping the house for a lifetime of free, silent energy production.  The fixing arrangement permits easy access for cleaning and servicing.  Because the panels are located a relatively long distance from the energy plantroom (approximately 40 metre cable run), large, 70 square mm cables have been used to reduce voltage drop.  The cables have been tightly strapped together to reduce inductive reactance and substantial metal oxide varistors (MOV's) along with careful earthing systems have been installed to reduce voltage spikes and surges from unwanted induced electromagnetic energy disturbances.

The solar photovoltaic array system is supplemented with a 400 watt, AIR403 ( AirMarine) wind turbine.  This turbine is a self-contained energy production system that is connected directly to the storage batteries through its inbuilt electronic charging regulator.  Turbine output (measured across a low resistance series shunt) is monitored and data logged using one of the PSA Inverter analogue inputs.  Although the wind turbine is only a very small component in the energy supply chain, it does provide a fascinating focal point that one never tires watching when the blades are turning.  It not only initiates interesting conversation with neighbours and visitors, but is a clearly visible renewables and greenhouse energy statement.  Frankly, it is not used often as it is very noisy in high wind situations - the penalty of an installation in suburbia.

Considerable effort has been put into surge and lightning protection of the complete household wiring and energy system.  The suppression design is based on the fact that the area is prone to electrical storms, plus the wind turbine, perched up on a metal pole at about 8M, is higher than surrounding buildings and is a potential lightning focal point (I tell the neighbours I am providing the neighbourhood lightning protection system at no cost to them!).  Distributed earth stakes individually connected by large, low impedance cabling is arranged to minimize potential differences between the grounded parts of the energy system.  Ground distribution over a large area assists the low impedance design.  We have put considerable effort into designing low impedance cabling systems (theoretically different to low resistance cable) to ensure effective earthing.  Low impedance earthing systems are  essential for good lightning protection as lightning discharge high current components consist of large, fast risetime, very high frequency, pulses of energy.

A large number of Metal Oxide Varistors (MOV) on the Direct Current (DC) circuit components and combination MOV/gas discharge surge suppressors on mains Alternating Current (AC) circuits assist in individual circuit over-voltage protection.  A large number of MOV/gas discharge suppression units are distributed throughout the entire AC electrical system reticulation.  A very high quality Transient Discriminating Technology diverter system is used at the Energex input to the property to ensure lightning strikes anywhere in the neighbourhood will not affect the household electrical system.  As a point of interest, gas discharge suppressors should not normally be used on DC circuits (above about 50 volts) as they may not be easily extinguished if activated by a surge pulse.   

The solar photovoltaic panel system has received the maximum permitted rebate (for a system with Energex supply availability) under the Government rebate grant existing at the time of installation.  This grant was jointly funded under the joint Office of Sustainable Energy (OSE) and Australian Greenhouse Office Photovoltaic Rebate Program (PVRP) to the value of $7,500.   In addition, the system has attracted 34 MWH of Renewable Energy Credit (REC) Certificates (for a 5 year period), providing another $630 rebate. The total rebate we have received is approximately 16.5% of the total renewables system expenditure.  Unfortunately, the current rebate has recently been downgraded (to about half its original level) by our very short-sighted Government who appear to be policy driven by coal, nuclear and oil industry pressure.

The renewables energy installation design permits selling back all excess electrical energy to Energex.   Although design capital cost will never achieve a full payback from energy sold, we expect export sales will always provide a small return for the life of the system, ie, the value of electrical energy sold through export should always be greater than any purchased (imported) electrical energy.  We are happy to accept a low return on investment now as we believe future Local Authority energy supply costs will not only rise dramatically over the next ten years or so, but contend Authority supply will become ever more unreliable.   In the mean time, we are comfortable with the thought our solar system design will provide us with abundant, silent, high quality power with flexibility and reliability, and it has the added advantage of improving, over time, on the return on our investment.

Spending a lot of money on renewables energy systems would be foolish without a corresponding effort to utilize modern, low energy, ultra-efficient appliances and lighting.  Our desire is to have a relatively "normal" electrical household so we are ensuring the house is fully equipped with the most energy efficient fluorescent lighting, LED lighting and household appliances available. Our research shows many new European appliances are now very energy efficient as well as being a delight to use.  It has been interesting shopping for these products, as in general, sales personnel are appallingly unaware of what efficiency and low energy advantages are really about (they seem to relate to cost of running issues only).  As an example of current efficient systems, the Liebherr "pigeon pair" fridge & freezer units, which we have installed, consume less than half the energy of the next nearest, most energy efficient, units that were available at the time of installation.  We have also purchased an ASKO dishwasher and an ASKO front loading washing machine, both units are extremely efficient in both electrical energy use and water conservation.  An interesting website for determining energy ratings of current appliances can be found at Energy ratings .

The house electrical wiring control system is designed around the Clipsal C-Bus computerized "smart" Energy Management and Lighting Control system and the associated Clipsal Homeminder system.  These intelligent systems have fully programmable lighting, security, control, monitoring and renewable energy data recording capability.

The C-Bus system provides appropriate dimming, energy management, temperature, light level and other sensor control and controlled system management and lighting based on programming, activity and learning.  It has a potential added advantage in reduced hard-copper wiring requirements (although looking at the wiring installation in our house, one would be uncertain whether there has been a saving!)   It is nice to be able to sit at the household PC and program any switch to control whichever light desired by a simple programming selection.  Integrated with the C-Bus system are remote control (hand-held infra red controls), telephone control and computer control via web-based systems, fully programmable audio, video, RF, data and communications systems and wiring .

The Clipsal Homeminder system, which is integrated into the C-Bus system, provides comprehensive security, fire, irrigation, home appliance and fittings monitoring, temperature, moisture level, data recording capability and control with digital, voice activated and associated telephone systems control and infra-red remote devices.

All lighting is low energy (almost all highly efficient flourescent fittings and the latest LED fittings for display and task lighting).  These are individually and intelligently controlled to conserve energy.  The low energy design and lighting ambience has been carefully designed with emphasis on reduced glare, task lighting and mood control.  All LED lights are dimmer controlled to minimize energy consumption and to provide correct display ambience.  The C-Bus and Homeminder systems detect temperature and light level from appropriate sensors, and drop into security or presence detection mode depending on owner/house occupancy.  In presence mode, the combination infra red and ultrasonic presence/movement detectors do such things as automatically dim up lights when you walk into a hallway, and dim down then switch off lights as you pass out of the hallway.  External blinds automatically lower when early morning sunshine irradiates the eastern windows of the house, then automatically raise after the sunshine no longer shines on these windows.  Toilet lights (automatically operate during dark hours) and odour vacuum exhaust fans (which exhaust directly through the toilet bowl area) automatically activate when these rooms are entered.  These exhaust fans provide time-delayed switch off after exiting room.

THE HELPERS...

We are grateful for the lively discussion, excellent support, assistance and solar design input provided by Christopher Darker ( Unisun ) who is a very forward thinking and innovative solar engineer based in WA.  Christopher supplied the majority of equipment at a most competitive price.  We have also had excellent input and advice from Heinz at ( http://www.ausolar.com ) on recent updates and modifications as well as the latest equipment at a very competitive price.  Ausolar is a Queensland based Company with a long and reliable reputation on solar installations.  

We also wish to thank our Architect, Justin Twohill, for not only many hours of stimulating design discussion, but his ideas on environmental factors, low embodied energy, simplicity, space saving and natural materials that can be so easily built into modern housing structures, fitted many of our perceptions and aspirations of future lifestyle.

We are pleased to recommend our builder, John Oliver ( http://www.rammedearthconstructions.com.au ) for those interested in rammed earth construction.  John has provided advice, assistance and guidance on something that is a little different (actually, what we see in our design is a "simple" house, but it is probably a builder's nightmare....).   John has been very patient with us as we have grappled with putting our ideas into earth, timber, steel, glass and nature to achieve relaxing comfort, serenity and simplicity.  We believe and feel he has an innate knowledge of what we are trying to achieve and this gave us comfort during the building phase.

Advice, guidance and installation work on the Inverter control systems, electrical wiring, data wiring, video wiring, hardware, switchboards. surge protection and earthing systems has been provided by Colin Harper, a fastidious electrician with a penchant for outstanding workmanship.

We have had excellent assistance in the design and installation of the Clipsal C-Bus, Homeminder and other related programming systems by Alastair Gillett of Gilletts Electrical.  This local Company,  fully accredited and trained by Clipsal, specializes in Clipsal C-Bus systems design, programming and installation. 

Without the assistance of these enthusiastic and very professional specialists we would be struggling to tie the whole project together.

BIBLIOGRAPHY

Much reading and access to the Internet has been underway for some years to build our knowledge base and to assist in our design and installation specifications.  Books and magazines we found helpful (in no particular order) are:

• ReNew Magazine ( ReNew ), an excellent, Australian, quarterly magazine touching on technologies for a sustainable future.
• Solar Technology Designers Catalogue, published by The Universality of the Sun ( Unisun ).  This catalogue, authored by Christopher Darker, has great design data, hints, how-to articles and a lot of realistic, commonsense advice.
• Warm House - Cool House by Nick Hollo.  Inspirational designs for low-energy housing.  An interesting collection of ideas and projects throughout Australia. ISBN 0 947277 22 6
• Renewable Energy.  Energy Efficient Building Design Resource Book, Certificate IV text book in Renewable Energy Technologies. Brisbane Institute of TAFE. ISBN 1 876880 03 1

GENERAL TECHNICAL DATA

Other important details of the house design are:

• 32 mpa concrete slab (negligible cracking thus impervious to termite penetration)
• Termite resistant structural design has 75mm clear exposed concrete around complete perimeter, termi-mesh where required on floor penetrations and keyed joints.
• Selected termite resistant/treated timber for ALL timber structural and roofing truss components.
• Extra strong, cyclone proof design and tie-down detail.
• Low maintenance design, natural finishes and reduced painting requirements.
• External (under eaves & covered walkways) sheeting designed to reduce external "nooks and crannies" to limit insect/spider habitat and ease cleaning chores.
• House design has distinct "resting", "working", "relaxing", "entertainment" and visitor accommodation areas with appropriate color and finishes to promote the differences between these areas.
• Three bedroom, two bathrooms, two "rest" rooms, both fitted with bidet's and efficient odour vacuum toilet bowl ventilation systems.
• Large study with integrated digital, video, LAN wiring and permanent data connection to C-Bus, Homeminder, Inverter, C-Touch systems and weather station hardware.
• Very large walk-in pantry/wine cellar with all surrounding walls constructed with rammed earth to provide a constant, cool  temperature through massive thermal inertia.
• Very large laundry/sewing room with large storage areas.
• Both sound and thermal insulation combined with natural materials to provide a quiet, thermally stable environment.
• Large, centrally located (in Pantry) electrical sub-board with sectioned off C-Bus system and comprehensive data/communications patch panels.  All household data, video, control and power wiring to each outlet/lighting point is returned to the main sub-board patch panels for central control, easy management, modification and fault-finding.  All 240 volt power and lighting circuits are on multiple Residual Current Device (RCD's -safety switches).
• Most ventilation glazing is of "louvre" type, thus permitting extraordinary breeze control and inclement weather control (ie, louvres can remain open in summer for breeze control yet prevent rain ingress).
• Installation of a large (1100 mm diameter), roof mounted, slow-revving fan that on those few hot days each year, can be computer and temperature controlled to start up and  create a pleasant draft throughout living areas.  The fan is mounted in the ceiling and exhausts air above the roof line.  This very low wattage fan can completely change the air in the house each 40 seconds.
• Wide eaves for weather protection (the northern side eaves width designed for passive solar calculated requirements).
• Ability to "see the sky" from all living areas - a relaxing and philosophical point of interest (based on our ancestors mode of living?).
• A very open and bright, light atmosphere.

When we first discussed the house characteristics (that we desired) with our Architect,  he asked us for a list of our design criteria to work with.  In lieu of the normal specification list of wants, our response was to provide the following design criteria specification (with tongue-in-cheek and some free license for dreaming).  Our response not only struck a sympathetic chord with our Architect, but it set a philosophical and conceptual direction that both of us enjoyed working with.

We produce the "design criteria" below for your perusal:

We trust you enjoy the content of this web page.  Web page links showing a chronological image essay of the project and technical data pages are listed at the head of this page.

Please feel free to contact us if you wish to comment on the project.   We would appreciate your interest.  Click on the mail box below if you wish to send us an e-mail message:

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