The principle idea is to be low energy and self sufficient as possible. The motivation behind this is a theory of peaking resources and peaking energy supplies. This will inevitably result in increased resource and energy costs and the focus of this project is to mitigate against these increases. Specifically regarding energy, there are many groups focusing on addressing this and raising awareness around this issue. Amongst them include ASPO, the Energy Bulletin and The Oil Drum all web based publications. Chris Martenson has a Youtube hosted 'Crash Course' Series and Chapters 17a, 17b and 17c deal with peak oil and related subjects. Overall this series offers an interesting spin to the industrial age and the issues it faces. Other sites address sustainability issues including the permaculture movement. Many publications and books also are challenging the way in which we live, calling for a dramatic change to the de facto standard and a return to a simpler existence. A specific reference to what changes we need to considered is offered by Power of Community. They have an interesting book and DVD on offer that illustrates quite graphically the challenges we face and how we can adapt to them.
Energy Efficiency
Principally there are two issues around energy. The first is embodied energy - the energy needed to create something and the second is the ongoing energy demand - the energy to maintain it. For instance a Prius motor car probably uses the same amount of embodied energy to make as does any similar car so it is not particular efficient in that regard. But it consumes far less energy (fuel) to operate than does a similar sized non-hybrid car. This energy audit can apply to almost everything. Embodied energy is one of the motivators for the recycling movement - rather reuse something than manufacture it from new. It's about energy and unnecessary energy consumption. And energy consumption in general has a significant environmental cost.
Reducing energy consumption can be simply achieved by a few simple design changes. Obviously, from a purist point of view, building a new house is not 'green' as the embodied energy in an existing house has already been 'spent' and is consequently much less than building a new house. The 'greenest' solution is to upgrade an existing building, but I am willing to sacrifice the embodied energy costs in an attempt to reduce future energy demands. A bit like buying a Prius.
Other attempts to reduce energy include:
- building in an accessible location, accessible to town and work. This will reduce transport costs.
- Positioning and orientating the house to achieve a cool house in summer and a warm house in winter using only sustainable heating or cooling.
- Being 'off grid' regarding food. If most of one's food can be locally grown i.e. in one's own garden, this represents a massive energy reduction especially as modern farming methods rely heavily on fossil fuels for pesticide, fertiliser and mechanisation.
- Using solar or renewable energy sources to heat wherever possible.
- Using solar to generate electricity - we do not have a suitable hydro option which would have been much cheaper and more reliable.
We're southern hemisphere based so the house needs to be north facing.
To reduce the early morning and late afternoon heat from the low sun angles, the house needs to be narrow on the eastern and western facades. By choosing a reasonable roof overhang (eave), the high summer sun can be excluded from the house during the bulk of the day in summer and deciduous trees can be planted on the eastern and western sides. The trees will help screen the house from the low sun angles.
In winter, the sun travels fairly low in the sky and will heat the house throughout the day, especially when the deciduous trees have lost their leaves. The roof eaves will not inhibit the winter sun from entering the house. Therefore the extent of the eaves are of critical importance.
This simple design element reduces the need for cooling in summer and heating in winter.
Other Design Aspects
By building thick walls increases the thermal mass of the walls. Rammed earth is perfectly suited to this and the outside wall thickness of the house will be 450mm. These walls will take a significant amount of time to heat up and cool down. The theory is that any heat that was absorbed during the day will be slowly released during the night. This promotes a fairly constant temperature within the house throughout the day.
We will be using a planted roof. This will be resting on a concrete slab and the combined thickness of the slab, soil and vegetation will act as a huge blanket over the house. This too will promote an even temperature within the house.
Underfloor heating/cooling will be provided by way of a pipe buried in the floor. To heat the house, hot water will be pumped through the pipe and cold water when cooling is required. The hot water will come from solar hot water unit supplemented by a wood burning stove and the cold water will come from a 600m pipe buried in the ground outside the house. The ground temperature remains fairly constant and a buried pipe makes use of the significant thermal mass of the earth to cool the water in the pipe.
Heat loss through windows is currently being investigated and I am researching the possibility of installing double glazing. This is an overkill where I live, but the benefits are great soundproofing, great thermal insulation and even offer a slightly improved level of security. In combination with Mediterranean shutters, the heat loss through windows and doors will be greatly reduced and the security greatly enhanced.
Finally, the stand has been cut into the slope so the rear of the house will appear almost 'buried' and the front will have a most stunning uninterrupted view with huge windows. This should reduce the effect of the prevailing wind and will also hopefully contribute to an even temperature throughout the year.
Offgrid Items
Water
Potable water will come from a borehole and harvested rainwater. To reduce water consumption, grey water will be treated and reused in the cisterns. Surplus grey water will drain into the food forest/vegetable garden. A well illustrated concept of greywater recycling is included in the design of Earthships by Michael Reynolds.
Food
There is quite a movement in our house to get off red meat, much to my horror. From a sustainability point of view this is a fairly essential step. A red meat eating commuter on a bicycle is less environmentally friendly than a vegetarian in a four wheel drive!
The intention on this front is to develop a food forest. Apparently the food yields are comparable between a food forest and a modern commercial monocultured crop. The benefit of a food forest is that it has several layers of food whereas a monocultured crop does not. A specific benefit of food forests is that they take little effort to maintain - 'forests look after themselves'. Predators abound and diversity of species is a fairly key requirement. There are a couple of interesting links worth watching in this regard. The first is A Natural World: A Farm for the Future by Rebecca Hoskings and the other is Establish Eden (Food Forest) With Love by Geoff Lawton. The plan is to plant between 500 and 1000 indigenous and exotic plants. Most will provide food in one form or another. What has been interesting is trying to research indigenous food sources. A useful source of information has come from 'The Lost Crops of Africa' book series published by The National Academies Press. They have a volume that focuses on each of the following: Grains, Vegetables and Fruits. All of the volumes can be downloaded in a pdf format for free or purchased at great expense. Not being an expert on much, I have managed to convince Neil Fishwick who runs a local indigenous nursery to advise me in this regard. Currently I am getting holes dug and have to organise 30 tons of 'kraal' manure - the stuff that is not full of ungerminated seeds.
These are my main points of focus in trying to reduce my energy footprint. As I rediscover the old ways of how we do things today - and are things that I can implement, I will update this post accordingly. I am sure it will include chickens, fish and any number of other interesting things. But in the meantime it's holes and manure.
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