NOTE: Make sure you read the first three posts (in order!) before tackling the rest, or it could be confusing: Post 1 is Designing the future, Post 2 is Setting up the problem, and Post 3 is Estimating basic requirements.


Monday, November 13, 2006

If you build it…

You are a genius. You just designed a 3000 square foot house completely powered by a 100-foot tall windmill and a massive rainwater cistern driving a paddlewheel. The three-story house boasts an intensive green roof, two wood-burning stoves, strawbale insulation, 2x12 framing timbers, and a greenhouse for your banana crop. Cool. Now build it.

If time and money are at your easy disposal, building your design may pose no problems. Of course, non-standard construction such as wide-board framing or green roofs will challenge most contractors, taking longer and costing more than conventional techniques. Plan on building it yourself instead? Anticipate things taking MUCH longer, especially if you have little experience or help. Building after Peak Oil effects have hit? Game over.

These concerns illustrate the reasoning behind including producibility requirements in Systems Engineering. It doesn’t matter how avant garde or functional a design is if it can’t be built with the available resources.

Consider your finances as you’re designing. Can you really afford a 30% efficiency 5 kW solar array with a tracking motor? Can you afford to use solar arrays at all? If not, what are the alternatives you can use to still meet your requirements?

In the context of our discussions, time is perhaps the most critical factor. According to some Peak Oil experts, oil production (and available energy) may already be declining. Can you risk taking five years to build your sustainable dream house? Can you risk even one? Maybe you should rethink your plans to ensure that you have a smaller-scale option available before you start on designing for more comfort.

There is also the matter of physically building your house. One or two non-experts can probably manage well enough to build an 800 square foot one-story house in short order, providing they have adequate tools and ingenuity. But suppose you plan on having a basement in rocky soil – your back will be in severe pain if you don’t have either a backhoe or 50 friends. Can you hand-mix enough concrete for it? Dubious. How about constructing your cistern? Think about what heavy equipment will be available or affordable over the course of your building schedule.

Producibility is just one more idea to keep in the back of your mind as you are designing, along with maintainability and reliability. Spending the time considering such things now could save you from heartache and failure in the future.


At 3:42 AM, Anonymous energyblog said...

I was reminded of a design tool used in former houses when I read this post.

It used to be that houses had a porch and awning. The porch would help with wind control somehow and the awning with cooling and heating. how?

well, as it turns out we live on a planet. And at certain times of the year, the sun is high in the sky, at other times low. So the awning is placed just so that the high sun of the summer hits the awning, and the low sun of the winter below it, allowing light into the house. Thus helping with cooling and heating.

Like much as I learn more, solutions are there, just our appreciation for what works needs a dusting off.


At 5:58 AM, Anonymous Jeff said...

Walter, the heating/cooling effect you're referring to is called passive solar. For heating purposes, the use of eves really only apply on the south side of a house (most earthen homes built in northern climates will have only one exposed side, usually facing south for this purpose).

You can supplement the cooling effect in summer by planting deciduous trees (that have foliage lose in the winter) south of house. This can provide shade for the entire house, not just the windows, which can have a dramatic cooling effect.

Obviously if you want solar panels on your roof planting trees that shade the house would be a bad idea. Also, planting trees isn't required for earthen homes that have soil roofs as the ground temperature remains fairly constant year round below the freeze line.

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