The Energy Autonomous House

Within the context of atmospheric pollution and climatic change, we must all accept some level of responsibilty; for contributing to the problems and, more positively, to become a part of the solution.


The Energy Autonomous House

By Robyn Francis

This article was originally published in the Permaculture International JournalThis article examines our domestic energy needs, and how they can be provided in efficient and non-polluting ways. We can begin to ‘clear the air’ in our own home environment.

Energy autonomy, or self-reliance is an option being more seriously considered now than ever before, and for good reasons.

It may be simply out of necessity for people moving into remote rural areas where ‘grid’ connection is either unavailable , or accessible only at massive cost. Even a few power poles can cost the earth and for roughly the same price a well planned autonomous energy system can prove cheaper in the the long term – there are no electricity bills rolling in every three months.

There can be other reasons for establishing an alternative source of electricity. These are based on the rights of ethical choice, choosing NOT to be dependent on a main supply that is generated by nuclear reactors or atmosphere polluting fossil fuels. In this situation we find many examples of complete independence, and numerous examples of incremental change; a gradual weaning off the grid through step by step installation of appropriate generating alternatives together with strategies to reduce overall energy consumption.

Whatever the situation or reasons for choosing energy self-reliance, the actual source and supply of power is only one part of a total planning process. Before we get carried away with all the possibilities presented by energy generating technologies, we first need to consider our energy conservation options. It is at the user end that appropriate technology begins, not at the generator.

Energy Needs and Conservation
As with any other element or factor in a Permaculture design, be it a chicken, vegie patch or pond, we must carefully analyse our own needs, the inputs and outputs or productivity of the element, how they will be supplied, and what benefits they offer to other aspects of the immediate environment. The design of a domestic energy system is no exception.

So what are our energy needs? We find that most domestic energy is used for space heating and cooling, hot water supply, food heating and cooling (cookstove and fridge), lighting, clothes washing, and various other household appliances. In 100% electricity dependent households in temperate or cool climates over 60% of energy is often used just for space heating and hot water supply, and in warmer climates electric hot water supplies are the greatest energy consumers, both of which can be provided readily by means other than electrical generation.

The three primary means of conserving domestic energy needs are:

1. Behavioural:
This includes things like: making the most of daylight hours; using space wisely in the home for different activities e.g. choosing the warm sunny side for winter daytime activities; dressing appropriately, wearing warmer clothing on winter days; snuggling up in a blanket with a hot water bottle for sitting around on cool evenings; cultivating the habit of switching off lights when they’re not in use; soaking pulses and dried foods to reduce cooking time.

2. House Design:
A house needs to be designed for it’s climate and sited to maximise the use of sunlight and protection from cold and strong winds. Many excellent publications are available with details on passive and active solar design techniques for houses in different climates. This needs to be combined with sensible landscaping, using deciduous trees on the sunny side and evergreen windbreak plantings on the cold, windy side. A perfect solar designed house will be rendered totally ineffective if the winter sun is blocked out by large evergreen trees. Efficiency in both heating and cooling can be enhanced by the addition of properly placed structures such as pergolas, glasshouses and shade houses.
The internal design of the house is critical, keeping active rooms (kitchen, dining, living, studio/office) to the sunny side, and placing the pantry (larder) and bedrooms on the cool side. Smaller rooms are easier to heat than large ones, and well pelmetted curtains and double glazing will reduce heat loss. Be sure to place heat emitting devices like cookstoves and heaters where they can give warmth to adjoining rooms – a chimney built onto an external wall is a shameful waste of heating energy.
Choice of materials will play an important role in controlling an indoor climate; their heat storage and radiation capacity as well as their insulating qualities.
Good house design can eliminate a lot of external energy use, not just in terms of electricity but also other fuel inputs including oil, gas and wood.

3. Technological:
This refers to our choice of appliances, their fuel or energy source and efficiency. Many appliances can be selected that don’t require electricity such as solar hot water services, wood conserving cookstoves and heaters, hand and pedal operated wash machines, solar clothes drier (clothes line), koolgardi safe (see box insert), gas appliances (fridge, cookstove), solar oven, haybox cooker, solar activated ceiling fans, to name but a few.

Do not discount the energy efficiency of non-electrical appliances – especially wood-fueled cookstoves and heaters. The combustion of wood is also polluting our atmosphere. It is a lot of hard work keeping up a constant supply of firewood, and expensive to pay someone else to supply it for you.

Electrical Generation
After all the above have been crossed off the list, there isn’t too much left to generate electricity for; lighting, radio, T.V., and a few other electrical tools and appliances that may be counted as necessary. Now that electrical needs have been defined, the next step is to select the appropriate form of generation.
While petrol and diesel generators are sometimes seen as the quick, easy solution, as power-output-per-hour goes they can be more expensive in the long term, and the problems of fossil fuel use, pollution, noise and external dependence are not solved.

The prime sources for stand-alone energy systems are solar, wind, hydro, and biogas (methane). Solar and small-scale hydro power are considered to have the edge over wind power in that they can recharge storage batteries more regularly, while wind has its frequency draw backs. The final decision will depend upon the parameters of the available resources; the quantity and frequency of available sunlight, wind, and flowing water. Biogas, in this respect, can be a more reliable energy source.

It certainly helps to de-mystify the marvel of how electricity works and understand its various forms. Put simply, DC (Direct Current) is used in most small scale home energy systems, usually in low voltages (12 volt and 24 volt). A battery bank stores the electricity which has been generated by sun, wind or water, so that it is available as required, and not just when the sun is shining, the wind blowing or the water flowing. 12 volt DC is sufficient for lighting, radio and TV, and an invertor can be used to change DC to AC (Alternating Current) for regular appliances. High voltage AC is the standard supply on the main grid.
You need to estimate fairly accurately how much energy you will need to determine the size of your system (e.g. how many batteries, solar panels, which hydro system etc.). This means selecting which lights and appliances will be used, working out how many amps or watts they each consume for how many hours a day. ( See what I mean by de-mystifying?)

“Energy from Nature” published by the Rainbow Power Company is definitely recommended reading, not just in terms of understanding energy systems, but for essential practical information on assessing energy requirements, making the right choices in selecting both appliances and generating systems, and ‘how to do it yourself’.

Available DC (12 volt) Appliances and Tools:
Lights, radios, stereo systems, TV, water pumps, soldering irons, drills, angle grinders, jigsaw, belt sander and several other hobby tools. Some models of washing machines can have a 12 volt motor installed – for further details see “Energy from Nature”

Case Study 1
This autonomous hydro system was developed on the tablelands in Northern NSW, Australia. A reliable, high volume, natural spring provides a constant water source from the neighbouring slope. The water is gravity fed through a 2 inch poly pipe to a header tank near the house, providing the daily domestic and garden water supply. A 12 volt motor generator (from a VW Beetle) was installed to generate electricity, activated by turning on the tap to fill the water tank. The tank is filled each evening when electricity for lighting is required, but sometimes the evening’s electrical requirements exceed the capacity of the tank, so it overflows. The system continues with the water overflow feeding into the duck pond. Due to the porous nature of the soil the duck pond has a slow leak and needs regular topping up. The ducks love the pond, and enrich its water with their droppings. When the duck pond fills, its nutrient enriched water overflows into the orchard, simultaneously watering and fertilising the trees. Altogether, a well planned system to suit the site, its needs and resources, in a way which fully exploits the potential of water, using it in many ways and reducing human labour. A lot of things happen when the tap is turned on!

Case Study 2
In West Berlin, a group of students formed a housing co-operative when the government threatened to evict them from the building they were squatting in. After long negotiations they gained legal access and ownership of the building and have developed it as an example of energy and resource efficiency. They severed their connection with the grid on moral grounds, not wanting to use energy supplied from a nuclear source. The climate in Berlin requires some form of space heating 8-9 months of the year, and hot water is a year-round necessity, so a central heating/hot water service was installed, fuelled by natural gas. The water heating process provides steam for electricity generation. Warm greywater (waste water from bathrooms, laundries and kitchens) is fed to tanks near the gas heater to pre-warm the incoming cold water, thereby reducing the amount of gas required for heating the water. Eventually they hope to replace natural gas with biogas (methane) produced on site from greywater and sewage. They are producing more electricity than they need, so surplus is sold back to the grid for a pittance. Since it is illegal to sell electricity privately, they are having serious thoughts about extending their co-operative membership to an adjoining building, who’s residents are keen to tap into the conscience clear, cheap power source.

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