Reducing our energy use
Our photovoltaic array is a 1.12 kilowatt system and was installed in late 2006 by John Cooke from Independent Power Systems and Nathan Stone, who now runs Solar Shop in Perth.
Our system produces 6-7 kilowatt hours on a sunny summer day, and this is enough to cover about two thirds of the electricity needs of all three “houses” that make up The Painted Fish.In winter our system produces 5 kilowatt hours on a sunny day and less if it is cloudy. Our first power bill after installation went from $150 to $15.The excess produced by our 1.5 kilowatt system at 21 means we are net producers over all.
The system has three main elements:
1. The panels which collect the sunlight and convert it into 12 volt AC electricity. We used poly crystalline rather than thin film panels as we had a restricted area of roof facing north. The inverter changes the 12 volt power into 240 volt AC.
3. The power meter measures how much power is being sent into or drawn off the grid. Extra power is bought by Synergy at 90% of its cost to consumers (less 10% GST) and the price varies throughout the day depending on the time—peak, off peak and shoulder. We now have a bidirectional digital meter but we loved the old dial one we originally had—you could watch the dial move backwards during the day!! (see the photo of our friends and the postman checking it out!)
Our system cost approximately $15,000 to install, and we received a rebate of $4,000. The rebate has since been doubled for this size system, and the cost of systems has gone down. With the price of residential power expected to rise significantly in the next few years and the proposed buy back scheme, photovoltaics begin to make good financial sense.
Installing a system also makes you extremely aware of the electricity requirements of various household appliances.
Ask Shani about what happens when she plugs in her hair dryer!
Solar Hot Water
We have had issues with the installation of this system and its effectiveness, and we are not really in a position to recommend it. But we would love to hear from people who have had experience (good and bad) with evacuated tube systems.
The “Solarium” Heating System
The solarium was created by adjusting the cottage verandah, since it was the only north facing aspect available. Tim had the steel beams made up, roofed the verandah in second hand 10 mm laminated glass, added clear café blinds ($1,300), and modified the louvers (purchased from Neil Bennett and Company).
The louvers can be adjusted depending on the time of the year, opening to 35 degrees in the middle of winter to let in the maximum sun and shut completely in summer creating a shady verandah.
In winter the solarium works much like your car dashboard; as sunlight enters through the glass it changes from short wave to long wave radiation which traps the heat. The solarium gets quite warm even on a cloudy day. By opening the upper and lower louver windows into the house a circular air flow is created, with hot air rising into the house and cool air sinking and being forced into the solarium. By shutting the louvers up as the sun goes down the heat is trapped in the insulated house.
And the results?— we don’t have before and after data but most guests find they do not really have to turn on the gas heater.
The idea for this system was taken from the Mawson House.
The “Waterfall” Cooling System
Trust a stonemason to think of this!
On hot days, the water from the small southern boundary courtyard pond is pumped over the limestone wall. Being extremely porous, the limestone soaks up the water and any south west breezes are picked up through the many holes, evaporating the water and blowing the cool air through the house via the louver windows. Basically this works like an old style Coolgardie safe.
The holes in the stone were created by using plumbing pipe as the stone was laid and then removing it once the mortar was dry. Ideally the pipes should have been set at 45 degrees between south and west. The stone work was completed by Tim and Nick Beach, and the copper water feature was created by Tim.
Why is the roof white?
Because white surfaces reflect heat while dark surfaces absorb it the roofs at The Painted Fish and some of the cottage walls have been painted with a special white reflective paint called Insultec.This stops the heat penetrating in summer and keeps the inside of the buildings cooler.
As a demonstration we have painted one of the bike sheds with Insultec and left the other one unpainted. If it is a sunny day try putting your hand on each of the sheds and feel the difference in temperature—and people still build houses with black roofs!
At the high point on the ceiling of each building at The Painted Fish is an “Ecovent”. These vents contain a diaphragm disk full of liquid with a low melting temperature. When the temperature increases, the liquid turns to gas and the diaphragm expands. Levers use this movement to open a butterfly valve venting the hot air outside, helping to cool the buildings. When it is cold, the vents close automatically keeping any warm air inside. At 18 degrees Celsius the vents are fully closed and at 30 degrees Celsius they are fully open. We recommend testing the vents with a hair dryer before you put them in—its great fun to watch them open and close!
MBR Sheetmetals used to import ecovents but apparently not any more – if anyone knows where you can get them from please let us know
Someone recently asked Shani and Tim what was the one thing they should do at a newly purchased property to make it more energy efficient. As Shani started muttering about putting in north facing windows, moving the living areas, adding verandahs . . . . . Tim quietly said “insulate”.
All the roofs at the Painted Fish are triple insulated, using a variety of different materials. On the carriage all the walls are insulated with air cell which operates in three ways.
1) Radiation—the double silver sides reflect back heat reducing radiation.
2) Conduction—the closed air pockets reduce conduction.
3) Convection—the aircell and framing create closed air spaces which reduce convection currents.
The studio and cottage walls are also insulated with air cell leaving a minimum 20 mm gap between the cladding and the air cell.
One summer an English couple stayed with us all through January. They commented when they left that they could comfortably work inside all day even on the hottest days. But let’s face it – when it gets above 40 degrees its probably best to sleep in the shade and head to the beach in the evening!
Good Solar Design - Includes Shade!
During winter when the sun angle is low (35 degrees at the winter solstice) the light and heat pass through the solar pergolas heating up the slab and internal masonry walls. The ponds reflect more light and heat up into the studio. At night the heat stored in the slab and walls seeps out into the studio and helps keep it warm. We are also contemplating installing full curtains to help keep the heat in at night.
During summer when the sun angle is high (82 degrees at the summer solstice) the solar pergola stops direct light from hitting the slab, which helps the studio stay cooler. The ponds act to moderate temperature and the evaporation helps cool the area.
The solar pergolas have relatively low thermal mass and good airflow to ensure that they cool down easily.Our solar pergolas cost about $900 to get made up by Needhams (MBR Sheetmetal will also make them) and Tim installed them, with a bit of help from Shani (she had the important job of telling him when they were straight—she doesn’t like heights!)
As well as solar pergolas we have used grape vines for shade. Any plants are great for shade as their transpiration gives an additional cooling effect. We had great success with beans as shade plants last summer.
Our main shade tree, the Japanese Pepper, is unfortunately not deciduous but it does give great cooling shade in summer and some protection from winter storms.We use light coloured Coolaroo shade cloth outside the carriage, studio and cottage in summer and it is much more effective than regular shade cloth.
Window Treatments in the Studio
You will notice the studio has louvered windows on the southern side of the building. These can be opened to 45 degrees to funnel cooling south westerly breezes through the studio in summer, and closed up tight in winter.
The west top windows in the studio bedroom have been tinted. The big old Japanese Pepper stops most of the afternoon sun but late in the day some sun hits the western windows and the tinting reduces this impact.
We are aware that to improve the heating in the studio we should really put pelmets and curtains on the big expanse of northern glass, but we can’t quite bring ourselves to block the view.
The coolest place in the whole studio on a hot still night is the balcony above the bath house. It is the perfect place to roll out a swag.
Window Treatments in the Cottage
As an experiment we cut out some pieces of air cell and just press fitted them into the windows.We found it make quite big difference so – as often happens with temporary measures – we are still using them.
The grape vine outside the front of the cottage also provides amazing shade for the summer months – and Shani made some winning grape jelly last year!
We built the studio and renovated the carriage before realising how power hungry 12 volt down lights are. This really hit home when we had the photovoltaic system installed. We have replaced incandescent globes with a mixture of compact fluoros and LED’s which we are trialling.
Although incandescent globes are due to be phased out, we feel a bit uncertain about the future direction of lighting. Compact flouros are now readily available in lots of shapes and sizes but recycling the used globes is costly and problematic due to their mercury content.
High intensity LEDs are becoming more readily available and affordable and have a very long life expectancy and very low energy consumption. We are currently also looking at some halogen based globes which are easy to recycle and use about half energy of conventional incandescent globes.
We have a wonderful Sparkie called Greg from Electrical Fault Correction and he is fantastic at keeping us up to date with lighting.