Cluster services together, especially hot water so that the pipes don't have far to go to deliver the water. This cuts down on heat loss, original installation costs, and repair & maintenance costs.
Face main windows north (in the southern hemisphere) to make maximum use of the sun for lighting and heating. (In the norther hemisphere they should, of course face south.)
Use wherever possible, heat-retaining building materials, and include large heat sinks in your design to store maximum heat over long periods. This is known as increasing your house's thermal inertia. An indoor swimming pool makes excellent energy sense. Water has an extremely high heat storage capacity. Some use has been made of bottles filled with water being built into walls. This can look quite pretty, with the light shining through the water-filled bottles, and also stores a large amount of heat that is released gradually through the night and succeeding days. In hot climates bottle walls and other thermal sinks would be kept out of the sun and exposed to night air so that during the day they can keep the house cool.
Use passive heating and cooling techniques, with convection and sensible placement of vents, in combination with solar heating/radiative cooling panels.
 Passive solar heating using a dark surface behind glass to absorb sunlight and heat air which rises convectively into the room. Flow is controlled by vents at top and bottom which can be opened and closed automatically so that you would have a warm home to return to even if you spent some time away. |
 A conservatory can heat air too, though not as efficiently, but has the advantage of being able to supply vegetables and scented plants and flowers in unfavorable climates. It will also help to keep the air from drying out too much. Plants give the air a pleasant alive quality. Stand in a rainforest and savour the air and you'll see what I mean. |
Heat can be stored for later use. The most efficient heat storage tank would be an indoor swimming pool, but simple, cheap heat storage tanks can be made out of anything that has a high thermal mass. Venting air through a tank of river stones is one solution I have heard of (though, I wonder if its efficiency might be reduced over time by cobwebs and dust).
 In climates where daytime is hot and night time very cold, heat from the day can be kept in a heat storage tank and then used to warm the house during the night. |
 Storage bins can also be used to store cold night time temperature to cool the house on a hot day. |
Solar electicity, after the initial expenditure, is power for nothing. Solar electric panels have some drawbacks though: they need to be cleaned from time to time to maintain their efficiency, they are prone to hailstorms and vandalism, and you need to either use DC (direct current) equipment or use an inverter to convert the DC to AC (alternating current). Inverters are inefficient, so you are best off to use DC wherever you can. Many companies make appliances for boats and caravans that use DC. However inverter efficiency has improved dramatically over recent years, so the need to use DC is not as great as it used to be.
You will need batteries to store power so that it can be used on dull days and at night time. Batteries can be quite expensive and do not last forever, even if rechargeable. You have to be extremely careful in the charge/discharge cycle of NiCad batteries otherwise their lives are terribly shortened. Ordinary lead-acid batteries, as used in cars, are the cheapest for initial outlay, and I think most battery manufacturers recycle the lead in old batteries so they don't pose the environmental problem they once did. Unfortunately lead-acid batteries are damaged by discharging them to less than about 75%, which means most of its charge must remain unused. Lithium ion batteries are still very expensive, but have become the most energy dense kind of battery, and can be recharged many more times than NiCad or lead acid batteries. While energy density is important for mobile applications (portable electronics and electric vehicles), it is much less so for home electricity storage. Lithium ion batteries do have a major flaw: the of risk bursting into a very hot flame if discharged too quickly, such as for example, if internal dendrites short-circuit the battery. Sodium ion batteries are similar to Lithium ion batteries, though are less costly, and are not a potential fire risk, but they do have a lower energy density. There are some new developments in rechargeable iron batteries. They have the potential to have many advantages, including very low cost. There are hundreds of possible battery chemistries. It will be interesting to see which ones end up being the best for stationary storage.
The most efficient electric lights used to be fluorescent lights, and they require AC, but LED lights have become the best, and they use DC power. In order to use them on AC they need a small converter, usually built into the base. When an AC-powered LED light fails, it is usually that converter that fails, not the light itself. LED lights operated on DC power would seem to be most reliable -- certainly cheapest.
Heat pumps have the extraordinary quality that they actually deliver more energy than is used to power them, but have the drawback that because they use moving parts and compressible gasses they will always require maintenance. It is possible to minimise time between breakdowns by using over-engineered equipment, however they are expensive. Every home already has a heat pump: they are commonly used to move heat from inside a refrigerator to outside it. I read some time back of a guy who heated his floors with heat pumped from the iced-over river near his home. One neat trick is to power a heat pump using heat. When I was a kid, a lot of fridges were powered by small kerosene flames, probably heating a stirling engine. I was intrigued by the concept of using heat to produce cold.
Even if you have tank water you will need to pump water. The most incredible way of pumping water that I have ever heard of uses a wonderful old device called a hydraulic ram (see http://www.lifewater.ca/ram_pump.htm). It pumps water using only the pressure of the water itself falling a small distance, and has one moving part. It is quiet, very low maintenance and requires no fuel. It doesn't pump large quantities fast, but works tirelessly as long as there is water to pump.
Care taken in initial design can lower building and insulation costs by using a good volume to surface area ratio. By lowering the surface area of the building as much as possible you expose as little as possible to the outside thereby lessening your insulation requirements. Also this has the effect of using less building materials. Think of it this way: each wall that gets shared with another room is one less wall that needs to be built.
Domes use less materials than straight-walled structures but are difficult to seal, and most furniture is made for straight walls. Cube-like double storey houses are efficient thermally and for material use, but are not good to grow old in, as stairs become a major problem in old age.
Calculate eave size on north walls (south walls if you are in the northern hemisphere) according to global latitude to exclude sun in summer and warm the room in the winter.
eave_width / wall_height = Tan (latitude° - 23.433°)
The 23.433° is the angle between the sun and the Equator when it is over the Tropic of Capricorn in the southern hemisphere's summer (or tropic of Cancer in the northern hemisphere).
At Melbourne (which is about 37° south) to exclude the summer sun, north facing eaves should be:
| eave_width / wall_height | = Tan (37.833° - 23.433°) |
| eave_width | = Tan (14.4°) * wall_height |
| eave_width | = 0.257 * wall_height |
To work out how far that will let the winter sun into the room, work out the same equation, but using the position of the winter sun instead of the summer sun, then subtract the eave size from it. The winter sun is another 46.866° lower than the summer sun because it is over the Tropic of Cancer for the southern winter (over the Tropic of Capricorn for the northern winter).
| winter_light + eave_width / wall_height | = Tan (61.266°) |
| winter_light + eave_width | = Tan (61.266°) * wall_height |
| winter_light + eave_width | = 1.824 * wall_height |
| winter_light | = 1.824 * wall_height - eave_width |
Summer shade can be enhanced using deciduous plants like grape vines on a verandah. Deciduous plants drop their leaves in the winter months allowing heat through to the house when it is needed most.
Fire-resistant plants, such as ivy, coleus, and the inch plant (Tradescantia zebrina) can afford some protection against fire.
Building with wood is inviting disaster -- it is like the witch in Hansel and Gretel who built her house of gingerbread. Wood is made up of sugar and alcohols (cellulose is a long chain sugar and lignin is a polymer of aromatic alcohols). It stores large amounts of energy and you must keep it safe from animals and plants that would like to consume it, and fire which is basically the energy releasing itself. Wood is not a thermally efficient material for building anyway -- much higher thermal inertia is gained by rock, concrete, metal, earth, and water. However one form of wood is very useful: cork. It not only makes beautiful floor tiles but is an excellent insulator not only of heat but also sound. Wood is undeniably beautiful though, so decorative use of it does make good sense. Bear in mind though, that it is like building with explosive -- if ignited it can be a death-trap.
Underground building has a number of fantastic advantages.
Underground building is not what it sounds like. The house is positioned similar to a normal house, usually on a hillside, but uses back-filling, usually covering the roof with excavated earth too. Careful use is made of insulation to make the house feel like it is at 6 or 10 feet below the surface of the ground. At that depth the temperature of the ground hardly changes year-round, and once you warm it, the house will stay at that temperature for days on end.
Water consumption can be a major problem in Australia, the driest continent. Our water utilities have now been sold off to private companies so we can't expect the prices to stay low. One of the most wasteful items in the house is the flushing toilet. Both the water and the human waste are discarded! Not only that, but we pay for the privelege of using it to cause ecological catastrophes. There is a Swedish design of composting toilet which requires no water, is completely safe, and lets you use the odorless, powdery, dry compost later in the garden. It is basically 2 large bins that get swapped each 6 months. In practice you don't move the bins but simply use the other toilet.
Layout of the house is quite important. Kitchens, for instance, should have only one doorway. It is important that the kitchen doesn't get through traffic. It is bad enough dealing with adults getting in the way while food preparation is underway, but it is positively dangerous if children are involved. You don't want small children or pets walking through the kitchen on their way to somewhere else when you are handling a large pot of boiling water on the stove. Speaking of the kitchen, benchtops need to be near the washing-up basin and the stove. Bench-top illumination is very important, as is handy access to power points. The pantry and fridge must be away from the sun, not on an external wall. It is nice to make the view from the kitchen one of the most pleasant in the house as so much time is spent there. If you own a dishwasher (they are extremely wasteful of water and energy) then make sure it is under one of the benches or the sink so that you don't have to carry dishes far.
The bedroom should be on the eastern side of the house to get the early morning sun. The lounge should be at the other end of the house to the bedroom(s) so that entertainment doesn't interfere with sleep. For similar reasons an office should be located away from sleeping quarters, though it may be sensible to have a bed handy to the office so that long working hours don't disturb your partner.
Open fireplaces, though romantic and comforting, are quite wasteful as most of their heat goes up the chimney. There have been many efforts to improve their efficiency, but the most efficient way of burning wood is inside an enclosed box like the so-called Franklin stoves. Even so, they are polluting and wasteful, and the chimney needs to be cleaned regularly, as slow-burning stoves build up soot and creosote on the inner walls of the chimney pipe. That build-up is flammable and can itself catch fire. This danger can be minimised by running the fire very hot from time to time to burn off the buildup before it reaches dangerous levels.
Incredibly, most homes use water taps that require regular replacement of washers in order to fix leaks, in spite of the fact that laboratory equipment has used taps without washers for centuries. Gas is much more difficult to seal in than water, yet gas fittings in the home require no washers. Taps that need washers are more than just an annoyance; they cost time and money, and waste water. A dripping tap that drips once a second pours more than 60 litres of water down the drain in a week, adding almost 800 litres to your quarterly water bill. If you are fortunate enough to use tank water this becomes an intolerable waste.