Trade studies for Peak Oil houses (Part 1)

Once you have developed your high-level requirements you can start looking at various design choices that meet those requirements. Although the requirements provide a set framework for your design, there are endless possible solutions. Your mission is to compare your different design ideas and determine which one best meets your requirements. During this process you may discover that some things are more important to you than others, or that some requirements are missing, unnecessary, or incomplete. The earlier in the process you figure these things out, the better.
To understand this process, it’s best to see an example. Below, I have three basic home designs sketched out (2 I drew myself, 1 from the National Park Service – see last post.) These designs are intended to meet the requirements for the Homestead Problem (minus food production) as found on the side bar. Pay no attention to scale or my ineptness as an artist – these are not intended as engineering drawings.
I’m going to break this topic into two posts for readability. In the next post we’ll identify advantages/disadvantages of each concept and their compatibility with the requirements.



“Loft House” Picture courtesy of the U.S. National Park Service
The Troglodyte Home (inspired by Glenn & Kathy of the Design/Build Forum) is essentially a modern cave. The Semi-Trog home encompasses a mostly underground structure with a more traditional ground level common area and most of the structure underground. The Loft House highlights many sustainable systems in an above-ground structure with underground water storage.

National Park Service Sustainable Design

The U.S. National Park Service has a fantastic guidebook for use in designing sustainable buildings. If you have a chance, I highly recommend you browse through the entire document (it’s not too long), but I selected a very choice snippet from Chapter 6 below.

The NPS sustainable design philosophy highly emphasizes education – visitors should learn about the building’s symbiosis with nature, gain an appreciation of the surrounding environment, and discover new ways to improve their own living. I think this is a philosophy we should all use when designing our homes and communities.

So many of us are struggling with educating our friends and families on the consequences of Peak Oil, climate change, and other dangers. By designing our homes to showcase nature, healthier living, and environmental stewardship we may lead them to that crucial point of realizing what is truly required.

From the U.S. National Park Service:

CHECKLIST FOR SUSTAINABLE BUILDING DESIGN

General

The design must

• be subordinate to the ecosystem and cultural context
• respect the natural and cultural resources of the site and absolutely minimize the impacts of any development
• reinforce/exemplify appropriate environmental responsiveness
• educate visitors/users about the resource and appropriate built responses to that environment.
• interpret how development works within natural systems to effect resource protection and human comfort and foster less consumptive lifestyles
• use the resource as the primary experience of the site and as the primary design determinant
• enhance appreciation of natural environment and encourage/establish rules of conduct
• create a "rite of passage"
• develop an entrance into special natural or cultural environment that emulates the respectful practice of removing shoes before entering Japanese home . . . leaving cars and consumptive values behind
• use the simplest technology appropriate to the functional need, and incorporate passive energy-conserving strategies responsive to the local climate
• use renewable indigenous building materials to the greatest extent possible
• avoid use of energy intensive, environmentally damaging, waste producing, and/or hazardous materials
• use cradle-to-grave analysis in decision making for materials and construction techniques
• strive for "smaller is better" . . . optimizing use and flexibility of spaces so overall building size and the resources necessary for construction and operation are minimized
• consider "constructability" . . . striving for minimal environmental disruption, resource consumption, and material waste, and identifying opportunities for reuse/recycling of construction debris
• provide equal access to the full spectrum of people with physical and sensory impairments while minimizing impacts on natural and cultural resources

Also, the design should

• consider phasing the development to allow for monitoring of resource impacts and adjustments in subsequent phases
  
• allow for future expansion and/or adaptive uses with a minimum of demolition and waste
  
  • materials and components should be chosen that can be easily reused or recycled
    
• make it easy for the occupants/operators to recycle waste

Context diagrams

Systems Engineering is full of tools to aid you in mapping out your design requirements. One such useful visual aid is a context diagram. The concept is simple: for your system, represent all inputs and outputs as arrows leading into and out of the system. The challenge comes in accurately identifying the scope of your design and how it interacts with the surrounding environment.

Context diagrams are key for identifying the most vulnerable parts of any system – the interfaces. If the joining of two systems is poorly understood or designed, both can fail.

Depending on your particular situation, your inputs/outputs will likely be different from these examples shown below. For instance, if you use a ram pump for outside water, your community is urban, or you’re still connected to the electrical grid, your interfaces will be different.

Notice that many of the community interfaces are the same as for the house, even though the house in this example falls within the community. Also note that waste items such as grey water, black water, and solid waste do not exit the community – they are recycled within it.

Peak Salt?

Salt is essential to our existence. Bloody wars have been fought over it, civilizations have risen and fallen because of its availability, and our own civilization depends on it every bit as much as oil.

Salt is obtained from two sources: Using seawater from our current oceans and mining halite deposits from ancient oceans. According to the Salt Institute, world salt production was 208 million tons in 2004, a figure that increases every year. In the context of our industrial civilization, there is an unlimited amount of salt – even far from the oceans, underground salt is staggeringly plentiful.

But consider salt availability after Peak Oil. If you live near the ocean, you can obtain salt using any of the dozens of ancient techniques – until rising sea levels erase suitable areas for salt flats. In the past, those living away from the coasts had certain options: they could obtain salt from animals that had consumed salt from subsurface deposits; they could obtain the salt directly from those deposits; or they could trade with those who harvested it from the far-away oceans – options that are in serious jeopardy post-Peak Oil.

Just as with oil, as our demand for salt grew we extracted the easy deposits first before moving on to the deeper (and harder to obtain) sources. Without heavy machinery, there are few accessible significant salt deposits inland.

If you intend to get your salt through animal protein, consider this: most livestock require salt supplements in addition to their feed. That salt must come from somewhere. Plus, aside from just keeping our bodies functioning, salt serves many other critical functions: preserving food, tanning leather, dissolving ice, and conditioning water. Life without abundant salt is significantly less comfortable than what we enjoy today.

Trade with the coasts is likely to develop as the sustainable solution to meet the salt needs of those living elsewhere, but it will take time for this natural system to develop (and with global warming affecting sea levels, production will be irregular at best – some believe the Roman Empire fell because of a slight rise in sea levels). It may also be worthwhile to figure out some simple salt reclamation methods. In the meantime, make sure your community design includes provisions for significant salt storage if you plan to live away from readily obtainable sources.

Water that flows uphill

In developing requirements for the Homestead Example, we determined that 280 liters/day of potable water was required to sustain a family of four. What design solutions can meet that requirement? Some options include using rainwater catchment basins, drilling wells, collecting lakewater, recycling wastewater, or combinations thereof.

Collecting water is one thing, but if we want water pressure for indoor plumbing, our design becomes much more complex. Normal tap pressure is around 40–45 psi, and unless your rainwater collection tower is 100 feet tall, you won’t come close to that without a pump. Of course, using an electric pump brings serious risks when considering a sustainable (post-Peak Oil) system.

If you have a nearby river, stream, or dammed pond, you may be able to take advantage of some straightforward physics to supply pressurized water to your house without mechanical pumps. The Country Plans Design/Build Forum recently had a good thread on this type of system, known as a ram pump.

In a ram pump, the energy of water flowing through a large orifice (pipe) is transferred to water flowing through a small one. Depending on the dynamics of the source and target flows, a ram pump can provide tap pressures more than adequate for a typical household.

An earthen dam with a drainage tube can be utilized for a ram pump; however, beware the risks of placing a home below a dam of any kind. Run the numbers and see if the flow is strong enough for you to place your home out of the way.

A ram pump can be used to pump water into a holding tank for later dispersal (which needs to be tall if you want good pressure!), which could integrate well with a water catchment system.

Cleanliness is a major concern with any water system, much more so than it was in the pre-industrial world. Fertilizers and other pollutants are found in most surface water and in shallow aquifers. If possible, have your source water tested by a professional and install water quality monitors on your system. If your only suitable water is not fit for drinking, consider using a ram pump for a pressurized irrigation system.

Filters and separators are sometimes necessary for processing healthy water, but make sure you choose solutions that make sense post-Peak Oil.

Also consider Sling Pumps and Pasture Pumps.

An example ram pump design. (Courtesy of Green Trust)

Building Communities: Who do we need?

So far this blog has focused primarily on developing single-family homesteads – while this is one design solution to a sustainable future, we need to ensure that we don’t lose sight of engineered community solutions to Peak Oil.

Rather than infrastructure, perhaps we should first examine who should comprise a community. I don’t propose this approach as a means to exclude people, but rather give community planners guidance to identify skills deficiencies. If a certain skill/trade/knowledge is found to be inadequate or missing, either someone from the community should acquire it or a new person should be invited.

I compiled a generalized list of occupations and skills that might be considered essential depending on the nature of the community. Please keep in mind that each community member should possess several of these skills, and preferably more than one person should be qualified in each area. Also consider the size and complexity of your post-Peak Oil community: Will you remain in a large city? Are you starting from scratch with a couple hundred people? Just a couple families? Is your community scattered or clustered?

In the near future (next few months) I will be transitioning this blog to a site that will include, among other things, a tool for community-minded people to meet up and develop plans based on individual skills, resources, and geographic locations. Keep checking back here as I improve on the PeakOilDesign concept.

Critical skills and knowledge for a post-Peak Oil Community:

Farming/Gardening (all types)
Nursing/General Practice Medicine
Specialized Medicine
Psychology/Psychiatry
Engineering (all types)
Teaching (Early childhood, K-12, advanced)
Security/Police/Military
Dentistry/Oral Hygiene
Cooking
Food preservation
Carpentry
Hunting/Fishing
Architecture
Clothmaking/Tailoring
Blacksmithing/Metalworking
Veterinary Medicine
Geology
Plumbing
Electrical Wiring
Meteorology
Religion/Philosophy
Seamanship/Sailing
Glass-making
Candle-making
Cheese-making
Paper-making
Firefighting
Animal training (dogs, horses, etc.)
Chemistry/Physics

Feel free to comment on or add to this list.

Framing a solution

Framing is one of the most crucial and complicated parts of constructing a house. In turn, one of the most complicated parts of framing is designing the roof. As a continuation of the earlier discussion on green roofs, I’ll give an introduction to some framing basics.

(A quick disclaimer: You shouldn’t start designing until you are satisfied that all requirements are in place. There’s no harm in learning about design solutions, however, and this discussion is intended to give you a further part of the ‘big picture’ of the design process.)

In discussing green roofs, I mentioned that roof loading can be in the range of 2300 – 7000 Pa (50 – 150 lbs/ft^2) compared to 5 – 20 lbs/ft^2 for a conventional roof. This is a significant weight addition that requires non-standard designs for the roof and frame structure.

Since this is such a complicated and important topic, it’s going to take us several posts to lay it out. First, you should check out the extensive tutorials and free technical resources at the American Wood Council. Go through the tutorials and play with the calculators in order to understand the basics – remember, not all of the conventional wisdom applies if you are building a high-load green roof. Also, Miedrn at Snippets&Bits has a good post on do-it-yourself framing books.

As you are digesting the information on these sites and books, here are some Peak Oil-based considerations to keep in mind:

1) Wider joists and studs allow for more insulation and wider spacing. Evaluate using 2x6’s, 2x8’s or larger instead of your standard 2x4’s. The energy savings and strength improvements could allow you to relax the design in other areas.

2) Make a note of the local woods available in your area. If lumber prices skyrocket during building, or you have to make future repairs (a certainty), are your local trees strong enough to meet your design requirements?

3) Shifting climates – What do climate change experts say will be the future weather trends in your area? Will snowfall rates (and your snow loading requirements) increase? Decline? Getting an answer can help prevent under- or over-designing.

4) Exceptionally heavy roofs may require the use of beams or a series of tightly-spaced joists to allow a large enough span with allowable deflection.

5) Consider hybrid systems – Think about a solar collector on one part of the roof and green roofing on the rest. Or shingles/green. Or a mix of green roofing types.

6) Make sure that you have a deep understanding of building structures, particularly your own. More than anything, framing a house is probably one area where you will want to employ a certified professional. If your walls aren’t plumb or your floors or ceilings aren’t level, you will have more trouble with the interior walls windows, plumbing, and so forth. However, if you can’t find a contractor (e.g. post-Peak Oil) or can’t afford one, you had best know all about building and repairing your structure – a poorly constructed frame could fail with devastating consequences.

Site Update: Example Problem

If you check out the sidebar, you'll notice new links to an Objectives and Requirements Document for the Homestead Project we've been developing. I'll post an updated version of the document as soon as I incorporate the results of some of the discussions we've had so far.

Give yourself a home warranty

Your house won’t be much use to you if the solar panel tracking motor is always failing, or your rainwater catch basin frequently springs leaks, or if deer invade your garden. For a system/community of any kind to be useful, it must be reliable, and reliability must be considered early in the design.

There are many strategies for measuring and achieving reliability. For systems like plumbing and electricity, reliability may be quantified using the mean time between failures (MTBF). Modern appliance manufacturers, for example, typically base their warranty policies on the calculated MTBF – a 5-year warranty on a refrigerator probably means they calculated the MTBF as a standard deviation or more greater than 5 years. The only way to obtain this information at the component level is through testing or operational experience. You can try to estimate MTBF for assembled components using statistics.

The reliability of a system is a direct consequence of its component parts:
Rsys = R1 * R2 * R3… So for a system with 10 sub-components to be 99% reliable, each component must be 99.9% reliable!

Some strategies for reliable design:

1) Redundancy, redundancy, redundancy – Using back-up components in series or in parallel can reduce the chance of system failure. If your anti-deer fence were to blow down, do you have a backup strategy?

2) Contamination/Corrosion – Think about ways to protect machinery from the elements or prevent algal/bacterial growth in your water system.

3) Modularity – Just as for maintainability, using modular components is important.

4) Inspection – Certify each component as you machine or install it. Verify all tolerances.

5) Fail-safes – Allows the system to continue functioning under less than ideal conditions. Examples would be a spillway for an earthen dam or a relief valve on a water heater.

Blast-off!

Atlantis has finally left the pad! I'm looking forward to a return to life without 12-hour midnight shifts...

A sewer-less future...

This is the first of many posts I’ll have on grey water recycling. Grey water is essentially all wastewater that doesn’t need a toilet (that’s known as black water). Most buildings discharge grey water into the sewer or septic system, but there are concerns with both methods. First, post-peak, how reliable will your city sewer/water treatment system be? Second, running less waste through a septic system means less demand on that critical system. And in both cases why waste such a large quantity of water that, when properly handled, can be used for irrigation?

The fundamentals of grey water recycling are not difficult to understand, but nevertheless there are so many examples where people implement it all wrong. For a stellar resource on the topic, try Oasis Design. As this post is only an introduction to grey water systems, I’ll focus on some key concepts to keep in mind when designing. We’ll work on sizing such systems later.

1) Grey water is not clean water – Seems obvious, but it's somewhat more complicated than you might think. Grey water can be applied directly some trees, but should not be used to directly water lawns or gardens. This can be accomplished using subsurface irrigation.

2) Grey is not poisonous water – While grey water should be handled properly, it is unlikely to make you sick. Plants you water with grey water are safe to eat (provided you don’t water the edible parts directly). And remember, the only chemicals in grey water are the ones you put down the drain.

3) Avoid pumps and filters – This is especially important for post-Peak Oil considerations. Pumps will break down, filters will clog. Use nature’s services: gravity and soil filtration.

4) Avoid storing grey water – Grey water is the byproduct of your laundry, showers, baths, and cooking; as such, it contains dirt and bacteria. If left in a holding tank for more than 1 or 2 days, these bacteria will frolic and putrefy. Your system should rapidly discharge into the soil.

5) Don’t over-design – Grey water recycling can be as simple as emptying your bathtub by bucket or a single discharge line into the soil. Your level of design should correspond to your maintenance availability, irrigation needs, and actual water usage.

In short, grey water recycling can have tremendous impact on your overall water budget. It can allow you to relax the requirements on your water collection system and help with growing your plants when it's designed carefully and implemented properly. More to come on this in the future…

Launch delay

The launch of Atlantis is on hold due a problem with the coolant pump on one of the fuel cells. As a side note, an elegant sustainable design feature on the shuttle is found in the fuel cell/life support systems (the current anomaly notwithstanding) – the water byproduct from the hydrogen/oxygen reaction is used by the astronauts on-orbit. It saves on launch mass and serves as a good reminder of how sustainability is key for space exploration. So do your part for the space program – design and test efficient systems :)

Calling the Maintenance Man

There are a number of practical considerations you should keep in mind early in the design process, which fall under the “-ilities” category – things such as maintainability, reliability, availability, and producibility. These characteristics of your system/community describe the practicality of building, using, fixing, and upgrading your project. I’ll talk about each one in turn, but for this post I’ll focus on maintainability.

Easy-to-maintain systems are especially critical for a post-Peak Oil community. If a pipe bursts, is there a plumber who can fix it? If your electric refrigerator fails, who can fix it? What parts will you use to fix it? How long will it take to fix? When specialists, available replacements, and time are scarce, the capability for quick and easy fixes is critical.

There are a few guidelines that will help you design maintainability into your system at all levels:

1) Replacement parts – Plan for acquiring and storing replacement parts for each of your systems, OR provide a method for fabricating replacement parts using materials on hand. You can be efficient about this – figure out which parts of your system will have a higher failure rate (e.g. valves or light bulbs) than others (e.g. pipe or wires) and plan accordingly. Ideally, you should have a plan for fabricating all replacement parts over the long-term, or accept that some parts of your system will eventually fail – oil scarcity = parts scarcity.

2) Modularity – Keep your interfaces simple so that replacement of a single component can happen quickly. For example, suppose you need to replant a portion of your green roof – if you designed your roof as a collection of modular containers, you can swap one out for a fresh one rather than spending all day replanting on a sloped surface.

3) Test points/Break points – Allow for trouble-shooting, especially in complex systems. Think of the circuit breakers in your house: they work to isolate a portion of your home electrical system and help you narrow down the source of problems.

4) Consistency – Try to use the same parts wherever possible. Rather than having one kind of faucet in the kitchen and another kind in the bathroom, consider using the same model. This will make your replacement parts a little easier to manage and limit the amount of information you have to remember about different types of components.

Go Atlantis!

Sorry once again for the dearth of posts. With all the problems and delays with the launch of STS-115, I’ve been running on empty. I’m still figuring out how to balance blogging with work, family, preparing for Peak Oil, and other endeavors, but I should be able to put more focus back on PeakOilDesign once we get our bird in the air.