Imagine twenty-five years into the future: we’ll have used up the rest of the accessible oil and cannot depend on fossil fuels for transport or production. Full electrification of our current energy use is not possible with current technology, so it wouldn’t be prudent to assume that has happened. If you want to build a house or other structure, you’d have to figure out how to build with what is near at hand.
In the country and suburbs, natural materials are easier to come by. Trees can be milled into timbers and boards. Earth can be dug and rammed into forms to make walls or stacked in bags. Clay can be smoothed over walls and polished for a lustrous finish. In the cities, recycled materials may be a clear choice. Bricks, lumber, insulation, windows, and wire can be salvaged from defunct buildings.
The goal of this challenge is to push builders to consider what it will be like putting up a structure in a future when fossil fuels are no longer available. While today it may be better to use natural materials imported from outside the city to build a sustainable, long-lasting house, in the future, this may not be an easy option and this challenge will drive builders to reconsider reclaimed, recycled, or novel materials close to where they are, be that rural, suburban, or urban. The goal is to develop strategies and solutions to meet the higher engineering standards of strength, durability, and efficiency of today with traditional, natural, or novel materials available nearby.
The Low Technology Institute is announcing a building design challenge that simulates this future: the Ten-Mile Building Challenge (TMB).
A Ten-Mile Building is constructed of materials that come from an average of ten miles or less from the building site.
That’s it. This simple metric cuts out unsustainable building practices and materials and is equally applicable in any region. Here, we will lay out the basic challenge concept, the certification processes (a free, self-certification or paid outside audit), additional utility certification, examples, and design processes.
Why Not a Green Certification?
Starting in the 1990s, building owners could seek certification for the sustainability of their construction methods and operation. The best known of these programs is LEED (Leadership in Energy and Environmental Design) but a veritable alphabet soup of accreditation is out there: BREEM, CASBEE, NGBS, Living Buildings, Energy Star, and many more. They are all essentially a way to measure the environmental impact and/or sustainability of a building project and/or its operation. They each have a point system and the “better” a design, the higher the points and level of accreditation. For example, out of a total possible score of 100, a LEED Platinum building received over 80 points, Gold over 60, Silver over 50, and basic Certified structure is only over 40.
The problem with scales like this (although their goal is laudable) is that they are not understandable to an average person. I’ve been polling people informally over the last month as to what does it mean to have LEED certification. Most come back with a fuzzy statement of environmentally friendly construction methods. Unfortunately this vagary permeates much of what is considered to be “green” today. Furthermore, people who are building with alternative, sustainable methods and materials ignore such certifications as mainstream greenwashing. And most importantly, in a future without fossil fuels, we will have to drastically change how we construct buildings. The ten-mile building challenge’s artificial restriction simulates some of the challenge designers and builders will be facing in a quarter century, plus it is both understandable to a regular person and accessible to DIY and alternative builders
Why Distance and Why Does It Measure Sustainability?
It is tempting to examine every aspect of a material and construction method to point out the best and worst when it comes to sustainable building. Today’s certifications do this, but it is prohibitively complex. Distance, on the other hand, is easy to measure. And chances are, the more sustainable something is to make, the more likely you are to find a local supplier. Complex chemicals must be created and combined, and this is done in a centralized location. But sawing lumber, for example, can be done anywhere. Clay is found across the globe. Straw bales are abundant.
The Materials Council made this graphic, showing how much material you can get for one ton of carbon dioxide emissions. This shorthand illustrates the same thing as a distance measurement, at least roughly.
But beyond the direct emissions, limiting distance forces builders to work with local materials that fit the landscape and environment. Part of the cachet of Italian marble countertops is in distant origin — it is conspicuous consumption. This challenge is the opposite: what beautiful structure can you make with what is near to hand?
Some of the most unsustainable materials must come from far away: concrete, steel, aluminum, synthetic chemical compounds, etc. Also, the more complicated a building product, such as plywood, drywall, and plastics, the more likely they are to be made at one (distant) location and have a wide distribution. None of these are feasible to produce without fossil fuels under current technology. On the other hand renewable (wood, straw) or reusable (stone, brick) have been produced before — and will be after — our dependence on fossil fuels and can often be had close at hand.
Distance is also a proxy of fossil fuel use — the institute is focused explicitly on reducing and eventually eliminating household dependence on this source of energy. We know that in a quarter century, we will no longer be using fossil fuels to subsidize our high-energy lives. Whether the transition is voluntary abdication or involuntary collapse, we need quality structures that can be built of local materials.
We live in a house that was built in 1855. The bricks were dug from a clay pit a block away. The wood was cut in a saw mill on the creek that runs through town. The doors and windows were made a block away in the Hoxie Sash and Door Factory, which used a horse gin to drive the machinery. The fact that durable and beautiful houses could be built locally less than two centuries ago should tell us that this is completely feasible — or more than that, since we have greater engineering and materials knowledge, meaning that we could rise to this challenge to create even better structures.
How Does It Work?
The point is to be straightforward, and the actual calculation is just that. We could average the distance travelled in a few ways, but the main consideration in shipping is weight. To get the average, the weight of each building material is multiplied by the miles travelled. Then the total mile-pounds from all the materials is divided by total weight, giving us a mileage. A simple spreadsheet is provided to do this calculation automatically.
For example, a Wisconsin doghouse with 50 lb of locally milled wood (4 mi) put together with 1 lb of nails from Ohio (300 mi) equals 500 mi-lb, divided by the total weight (51 lb) to give us 9.8 miles for the average total distanced travelled per pound. Metric folks can do the same thing with a 15-km limit (because kilograms divided by kilograms will cancel out; unit of mass does not matter as long as it is the same throughout the process).
That’s it.
What About Building Utilities?
In addition to the structure, we must have a way to create dependable utilities and livable spaces, and we do that through an optional challenge of local energy use. It is unlikely that raw materials for anything electric will be mined and manufactured within a short distance, for example. Hyper-efficient appliances may have to be imported, but over the course of their use-life, they will save enough emissions to be worth the manufacture and shipping. Or, closer, more reliable options may be less efficient but use more local abundant energy. We will weigh the startup and lifetime energy costs of different solutions to heat, cool, and light interior spaces as well as provide water and deal with “waste.” This will be done through a percentage score, as in:
What percentage of the structure’s utilities (measured by embodied emissions) are provided for within the ten-mile radius?
The higher the percentage, the better the utilities. Self-certification requires the builder’s report and calculations, while formal certification requires a paper trail for audit.
We can look at a simplified example comparing a woodstove and heat pump for space heating. The woodstove comes from China (travel: 144 kg CO2e) and is made of about 195 lb of iron (ca. 100 kg CO2e). Burning four cords of wood per year would put out 464 kg CO2e producing 80 million BTU. Total off-site energy use is 244 kg CO2e, and burning local wood generates 9280 kg CO2e over twenty years — meaning 93 percent of heating energy is generated in the ten-mile zone. The heat pump system has an estimated embodied CO2e of 1563 kg (production and travel). But then the heat pump would need 4 MWh/year of electricity in a cold climate, equating to solar panels requiring 760 kg CO2e to produce. This brings the total emissions to 2323 kg CO2e of off-site energy for system production vs. 80 MWh generated energy over two decades, equivalent to 56,695 CO2e — meaning 96 percent of heating energy is generated in the ten-mile zone. Although the heat pump is more likely to require complicated maintenance, both are good options compared to constantly importing natural gas, heating oil, propane, or even off-site-generated electricity, which all score 0 percent. The stove, however, is likely to last much longer than this 20-year use life. A mass heater built of local and reclaimed materials, though, may score even higher than a woodstove or heat pump!
What about Livability and Appearance?
One point that may be the most challenging is creature comforts. Because we are used to such cushy interior spaces and systems that minimize any inconvenience, from feeling momentary heat or cold to high-energy appliances, we are conditioned against the strictest efficiencies and eco-friendly practices and designs. Thus it is important that people are comfortable in these new spaces, as they will not be adopted unless they are seen as attractive and livable. Because this is subjective, it will be graded on the letter scale and open to interpretation and discussion. Basic standards for each grade will be given and must be met to achieve certain grades. A plus or minus may be applied for particularly aesthetically pleasing (or displeasing) structures. A self-certification is graded by the builder, while a panel will vote on a score for a formal certification.
Certifying a Ten-Mile Building Challenger
The challenge should be to construct a ten-mile building, not the certification process. Here we’ll outline the simple steps to get certified, but the most important thing is to keep notes as you go, which will make your task to fill out the form easier.
Self-Certification or Audited Certification?
We’re a nonprofit and our goal is to recognize sustainable alternative building methods, not make money. Cost of certification will not be a barrier to attempting the ten-mile challenge. Those who are interested in pushing themselves to build under this rubric can complete a free self-certification. It is on their word to enter correct and accurate information on the form. They are free to call their structure a ten-mile building. Only in contexts with legal ramifications do they need to specify self-certification, for example, in advertising a building for sale (e.g., “this structure was built in a sustainable way and is a self-certified Ten-Mile Building”).
For those who seek more formal recognition, the Low Technology Institute staff will audit the challenge certification. With this process, a builder can list the structure as a certified Ten-Mile Building for advertising or whatever legal purpose. If desired, the structure can be listed on the Ten-Mile Building registry maintained on the institute’s website. The builder is responsible for submitting written or other documentation (e.g., photos of clay being dug on site to fill earthbags) to corroborate each listed item. The fee for formal certification is 0.1 percent of the building’s total cost.
Certification Form
The form is a fillable PDF available here:
The form has four sections: a cover sheet, structural distance audit, utility audit, and aesthetics and design rubric. Only the forms for the certifications you are seeking need be completed (e.g., if you just want the ten-mile building challenge certification, only the first two pages are needed). Here we will walk through the instructions section by section.
Cover Sheet
Applicant Information
Provide the contact person (or firm’s) information, including correspondence address, telephone, and email. This should be the name of the person or entity seeking certification and completing the forms, as they will be contacted with any questions. Do not use the address of the building, unless that is also the correspondence address. Physical location comes in the next section.
About the Building
Complete this section about the particulars of the building and certifications sought. An optional building title may include the business, family, or entity to occupy the completed structure (e.g., “Nowinsky Family House,” “John Muir Center,” or “Appalachian Design Firm”). Address should be the physical location of the structure, preferably a postal address or other easily identifiable locator. Coordinates should be centered on the physical middle of the building and can be found using Google Maps, if unknown. Measure the exterior perimeter to calculate the structure footprint in square feet or meters. Additionally, calculate the number of enclosed square feet or meters of usable space (does not have to be finished). Include the number of floors including basements and usable attics. A general total or estimated cost requested (can be rounded).
Tick a box for each certification sought. It is assumed that all buildings will complete the ten-mile portion, and no box need be checked for this — only the additional utility or aesthetics and design portions.
Self-certification, as described in the previous section, is free and on the honor of the person completing the certification. This form should still be submitted to the Low Technology Institute for its records. Formal certification requires an audit of the submitted files, as well as all supporting documentation. To support the staff time to complete the audit, a fee of 0.1% of the building cost is required. For just a ten-mile building challenge certification, only the cost of the primary building materials listed need be tabulated to calculate the fee. If utilities are also to be certified, then the cost of those systems should also be included in the calculation. Aesthetics and design certification is a flat fee of $100, to compensate the panel who will assess the rubric and attached images.
Finally, summarize the building by describing the principal building materials, utilities, and a short narrative explanation of the conception and use of the building. This description should summarize the primary points you’d like others to know about this building, and may be listed along the with the title and a photo in promotional materials.
Note that the information you provide for description, building name, city and state location, and photos may be used for promoting the Ten-Mile Building Challenge. We will contact you if we would like to use any materials you submit beyond these basics on our website or social media. Please check the box to indicate your understanding and consent.
Finally, sign and date the form, by typing applicant’s name and adding a digital signature (preferred) or printing, signing, and scanning the completed cover sheet.
Structural Distance Audit
This form lists and calculates the distance travelled of the primary building materials. Those materials are defined as anything that would appear in typical architectural drawings. Structural members, wall and floor materials, roofing, windows, insulation, and even wall treatments should be included. Utilities, including HVAC, plumbing, electrical, and others will be addressed in the utility audit (if sought) and are not included in the ten-mile structural audit. Minor decorative elements are not included unless they constitute or stand in for another structural element. A rule of thumb is that if it is permanently attached, it should be included. For example, a mosaic of glass embedded in mortar over a wall should be included, but a framed painting hanging on a wall should not.
List each item as a group of like elements on a line of the form. A group of like elements all come from the same location and are of the same material. Pine timbers sawn at a mill are one group, separate from oak boards sawn at the same place, for example.
The weight of items can be calculated and must not be necessarily measured for each. Circle the unit used (lb or kg). Standard weight of board feet can be multiplied out to calculate the weight of all timbers in a group, for example. The average weight of ten earthbags can be measured during construction and multiplied by the total number of earthbags.
The origin of an item is the distance from the building location of where it is collected, processed, or purchased, whichever is greatest. For example, timbers cut four miles from the construction site but milled six miles away should be listed as coming from the mill. Nails bought at a hardware store ten miles away, but produced two hundred miles away are listed as coming from the producer. Additionally, the distance for reclaimed or salvaged materials is only to the place from where they were gathered by the applicant, not where they were manufactured. For example, Milwaukee bricks taken from my neighbors’ chimney only count for the distance to their house. Note that no more than 10 percent of a structure’s weight can come from newly manufactured materials produced at a factory that happens to be within 10 miles. For example, an all-concrete structure next to a concrete factory is not in keeping with the spirit of this challenge. Cast off or waste material, however, that is legitimately discarded by the factory can be used as if it is reclaimed or recycled (i.e., it doesn’t count against the 10 percent).
The distance is the miles or kilometers (circle one) from that origin. Multiply the distance by the weight and enter it in the “Total mi-lb” column. Sum the total weight and mi-lb at the bottom of the sheet. If more than twenty-six primary building materials are used, print additional copies of this sheet. Make sure to note at the top right, page number and total pages. When all pages are complete, add all page total mi-lb and weights on the first page, dividing the first by the second. This is the total mileage average per lb (or kg).
Additionally, formal certification requires scans of receipts or photographs associated with each material should be appended to the form. Each receipt or photograph should be labeled to identify the item. For example, the label “2-s” on an item on a receipt would refer to the item listed on page 2, row s.
Utility Audit
Heating, cooling, water, sewage, and electricity utilities can each be audited. Not all must be audited, but only those that are examined can be listed as part of the ten-mile building challenge. “Our ten-mile building includes an audited heating and electric system.” We recognize that in some jurisdictions, it is against code to deal with one’s own water and sewage, which makes certification at a meaningful level difficult.
The utilities are scored on a percentage scale, representing what percent of emissions equivalents are generated from local sources of power. A score of 100 percent means that all the embodied emissions of the system and fuel or power comes from within ten miles of the building.
Heating
About 42 percent of domestic energy in the US goes to space heating. In this challenge, builders should consider how to warm their structures using as much local resources as possible. This can be a high-tech heat pump or hydronic system with solar power, which we will use as an example here (to illustrate a more complex system), or a tried-and-true masonry stove of salvaged brick fired by local firewood.
Heating System: First describe the system in a sentence, noting the heat-producing appliance, how it is distributed, and how it is fueled. For example, “A solar-powered electric boiler with hydronic radiators,” or “Efficient Danish woodstove heating by convection and radiation, fired by local deadwood.”
Thermal Enhancements: Note any thermal enhancements you’ve made to the structure, such as insulation, solar gain in design, and/or surface:volume ratio. The higher the surface:volume ratio, the more heat loss a building will experience. A sphere has the least surface per volume, and it is no coincidence that animals in cold regions are more spherical. Houses in northern and southern climates may make different use of this design feature.
System Embodied eCO₂: Calculate the embodied emissions of the system production, expressed in carbon dioxide equivalents (eCO₂). This may be available from the manufacturer, but it may also require research and some reasonable approximation. To that, the emissions of any purchased enhancements and transportation emissions should be added. For formal certification, additional pages of citations and information should be attached to “show the math” as to how this figure was reached. The more complex a system, the higher the embodied emissions, generally. For our hybrid system, we’re estimating 2323 lb eCO₂ (1563 lb for the heating system and 760 lb for the panels).
Heating Fuel: Indicate the type of fuel used. If a system is hybrid, indicate both types and the percentage of each in parentheses: a solar-hot-water-panel-assisted electric boiler system would indicate “solar (25%) | electric (75%).” These percentages, if present, will follow through the reset of the calculations.
Annual BTUs: Indicate the annual heating BTUs and if this is an estimated or actual figure.
Annual Fuel Use: Similarly, add the annual fuel use and if it is estimated or actual. If a hybrid system is used, indicate this figure for each: “solar: 1 MWh, electric: 3 MWh.” In this case, a solar hot water heater would give the figure of offset electric power it saved.
eCO₂ per Fuel Unit: For each fuel type, give the eCO₂ per unit. For wood, multiply number of million BTUs/cord from this chart, and multiply that by 200 lb eCO₂/million BTU (e.g., white oak: 29.1 mmBTU/cord × 200 lb eCO₂/mmBTU = 5820 lb/cord). For other fuels, consult this EPA chart (and see formula at end of paragraph to calculate eCO₂). Emissions for grid electricity powering a system should be calculated as the average current emissions of your location’s grid, which can be determined using the following box. Solar, wind, hydro, and other sources with zero emissions during generation (not counting embodied costs) can be listed as the eCO₂ saved in your location per k- or MWh. That figure uses this same equation as grid power to calculate emissions per unit. Give this for each fuel type, if applicable: “solar: 1656 lb/MWh | electric: 1656 lb/MWh”; in this case, they are both the same.
How to Determine Your Local Emissions per k- or MWh
Enter your zip code at the EPA’s eGrid Power Profiler. Find the carbon dioxide equivalent using the following formula: lb eCO₂/MWh = CO₂ + (CH₄ × 25) + (S₂O × 298). Convert to eCO₂/kWh by dividing sum by 1000.
% of Fuel from ≤10 mi: Indicate what percent of fuel or power comes from within ten miles of the structure. Wood-fired systems, for example may get only a percentage of their fuel from close by. Most other systems are either 0 or 100 percent. For our example hybrid system, this is: “solar: 100% | electric: 0%.”
Annual Local eCO₂: This is calculated by multiplying the units of annual fuel use by the eCO₂ per unit and by the percent of fuel (expressed as a decimal from 0.00 to 1.00) from ≤10 mi. If hybrid fuels are present, complete this calculation for each. Finally, multiply the result by 20 years as the baseline system lifetime used in this calculation. This is the “Lifetime Local eCO₂.” In our hybrid example, then, we have lifetime: “solar: 33,120 lb | electric: 0 lb” (solar: 1 MWh × 1656 lb/MWh × 1.00 × 20 yr/lifetime | electric: 3 MWh × 1656 lb/MWh × 0.00 × 20 yr/lifetime).
Annual Distant eCO₂: This is the inverse of the previous calculation. The annual units of fuel, multiplied by emissions per unit, multiplied by the decimal percentage from the previous calculation subtracted from 1. For example, if 80 percent of fuels are local, the previous calculation would use 0.80 and this one would use 0.20. The product is multiplied by 20 years. In our hybrid example, then, we have lifetime: “solar: 0 lb | electric: 99,360 lb” (solar: 1 MWh × 1656 lb/MWh × (1.00 – 1.00) × 20 yr/lifetime | electric: 3 MWh × 1656 lb/MWh × (1.00 – 0.00) × 20 yr/lifetime).
Add the above system embodied emissions to the lifetime local and distant emissions for the total lifetime emissions. Divide the lifetime local emissions by the lifetime total emissions to get the decimal percent of local eCO₂. Multiply this by 100 to get the final percent local eCO₂. For our example, the equation would be: 33,120 lb divided by 134,803 lb lifetime total emissions (2323 lb [embodied emissions] + 33,120 lb [local] + 99,360 lb [distant]), giving 0.25, or 25 percent. Meaning a quarter of the energy for heating came locally.
Cooling
About 6 percent of domestic energy in the US goes to space cooling. In this challenge, builders should consider how to cool their structures using as much local resources as possible. This can be a high-tech heat pump with solar power or simple earth tubes with grid-powered fans pulling in cool air; we’ll use the latter as an example throughout.
Cooling System: First describe the system in a sentence, noting the cooling appliance, how it is distributed, and how it is fueled. For example, “A grid-powered earth-tube system,” “a solar-powered fan-driven evaporative cooler and windcatcher,” or “a heat-pump system fueled by hybrid solar and grid electricity.”
Thermal Enhancements: Note any thermal enhancements you’ve made to the structure, such as insulation, shading design, and/or surface:volume ratio. The higher the surface:volume ratio, the more heat loss a building will experience. Animals in tropical climates are lanky to help radiate heat from their bodies. Houses in southern climates may make strategic use this design feature.
System Embodied eCO₂: Calculate the embodied emissions of the system production, expressed in carbon dioxide equivalents (eCO₂). This may be available from the manufacturer, but it may also require research and some reasonable approximation. To that, the emissions of any purchased enhancements and transportation emissions should be added. For formal certification, additional pages of citations and information should be attached to “show the math” as to how this figure was reached. A rough estimate for a 600-ft, 12-in earth tube system buried to 6 ft with 800 CFM fan is about 3400 lb.
Cooling Fuel: Indicate the type of fuel used. If a system is hybrid, indicate both types and the percentage of each in parentheses: a solar-powered and electric heat pump system would indicate “solar (25%) | electric (75%).” These percentages, if present, will follow through the reset of the calculations. For our example, 100 percent of the system is powered by grid electricity.
Annual BTUs: Indicate the annual cooling BTUs and if this is an estimated or actual figure. In our case, a 2000-ft² house cooled with 40,000 BTU/hr earth tube system. We’ll use the EPA estimate of 750 hr/year, giving 30 mmBTUs (million BTUs; be sure to keep later BTU figures in the same scale).
Annual Fuel Use: Similarly, add the annual fuel use and if it is estimated or actual. If a hybrid system is used, indicate this figure for each: “solar: 1 MWh, electric: 3 MWh.” In this case, all the power comes from panels, running a simple electric fan to pull in the cool air, at 300 W/hr for the EPA estimated 750 hr/year, giving us 225 kWh.
eCO₂ per Fuel Unit: Emissions for grid electricity powering a system should be calculated as the average current emissions of your location’s grid, which can be determined using the formula in the call-out box in Heating, above. Solar, wind, hydro, and other sources with zero emissions during generation (not counting embodied costs) can be listed as the eCO₂ saved in your location per k- or MWh. That figure uses this same equation as grid power to calculate emissions per unit. If your system uses fossil fuels, consult this EPA chart (and use formula above to calculate eCO₂). Give this for each fuel type, if applicable: “solar: 1656 lb/MWh | electric: 1656 lb/MWh.” In our example, we’d list just the single grid electric figure.
eCO₂ per BTU: For passive or low-energy systems, note the emissions equivalent saved compared to typical systems at a rate of 15 mmBTU/MWh (CEER of 15 BTU/Wh). This is the typical efficiency of a modern air conditioner and is what a passive or low-energy system is saving. Divide the eCO₂/MWh for your area (just calculated) by 15 to get the emissions per million BTUs saved. For our example location, then, we’re saving 110.4 lb/mmBTU (1656 lb/MWh ÷ 15 mmBTU/MWh).
% of Fuel from ≤10 mi: Indicate what percent of fuel or power comes from within ten miles of the structure. For our example, 100 percent comes from grid power, but hybrid systems should list the components individually: “solar 100% | electric 0%.”
Annual Local eCO₂: This is calculated by multiplying the units of annual fuel use by the eCO₂ per unit and by the percent of fuel (expressed as a decimal from 0.00 to 1.00) from ≤10 mi and then adding BTUs generated multiplied by emissions per BTU. If hybrid fuels are present, complete this calculation for each. Finally, multiply the result by 20 years as the baseline system lifetime used in this calculation. This is the “Lifetime Local eCO₂.” In our example, we’d get 66,240 lb eCO₂ lifetime ([ [225 kWh × 1.656 lb/kWh × 0.00] + [30 mmBTU × 110.4 lb/mmBTU] ] × 20)
Annual Distant eCO₂: This is the inverse of the previous calculation. The annual units of fuel, multiplied by emissions per unit, multiplied by the decimal percentage from the previous calculation subtracted from 1. For example, if 80 percent of fuels are local, the previous calculation would use 0.80 and this one would use 0.20. The product is multiplied by 20 years. In our earth-tube example, distant energy is used for the fan, resulting in 7452 lb eCO₂ lifetime (225 kWh × 1.656 lb/kWh × [1.00 – 0.00] × 20).
Add the above system embodied emissions to the lifetime local and distant emissions for the total lifetime emissions. Divide the lifetime local emissions by the lifetime total emissions to get the decimal percent of local eCO₂. Multiply this by 100 to get the final percent local eCO₂. For our example, the equation would be: 66,240 lb divided by 79,092 lb lifetime total emissions (5400 lb [embodied emissions] + 66,240 lb [local] + 7452 lb [distant]), giving 0.84, or 84 percent. Meaning a most of the energy for cooling came locally.
Water
We debated about whether or not the amount of water used by different house systems should be included in this audit, but decided that measuring these different uses would be impractical. We anticipate that those interested in this challenge will not be using scarce water in a desert for maintaining a green lawn.
See the above instructions for heating and cooling to fill out this section. What follows is water-specific changes and an example.
Water System(s): We’ll use the example of: “Conventional well-pump with pressure tank and 200 gal. rain barrels.”
Water Source(s): “Well, rain.”
System Embodied eCO₂: “Well casing, pump, and pressure tank: 350 lb; Rain barrels: 120 lb; Total 470 lb.”
System Power: “Electric, gravity”
Annual Energy Use: “Well pump: 350 kWh; rain barrels: 124 kWh.” In this case, the amount of energy saved by the rain barrels is listed (i.e., gallons collected vs. energy needed to pump those gallons; either by actual measurement or estimation).
eCO ₂ per Energy Unit: “1.656 lb/kWh”
% of Fuel from ≤10 mi: “26%” from rain barrels is 124 kWh divided by total (350 + 124 kWh).
Annual Local eCO ₂ : “204 lb” from 474 × 1.656 × 0.26, giving lifetime of “4080 lb.”
Annual Distant eCO ₂ : “581 lb” from 474 × 1.656 × 0.74, giving lifetime of “11,620 lb.”
Lifetime Total eCO ₂ : “16,160 lb” from adding last two values plus embodied emissions of system.
Local eCO ₂ Percent: “25%” by dividing lifetime local emissions (4080 lb) by total lifetime (16,170 lb) and multiplying by 100. In this case, the percentage could be improved by using more rain water or installing solar panels to run the pump. Or a water-pumping windmill could be used.
Sewage
See the above instructions for heating and cooling to fill out this section. What follows is sewage-specific changes and an example.
Sewage System(s): We’ll use the example of: “Conventional septic system with greywater and some human waste collection diverting 50 percent of outflow.”
Water Source(s): “Well water (see above).” The emissions of the water supply are not required unless the water system has not been audited above.
System Embodied eCO₂: “Septic System 1245 lb; Greywater: 120 lb; Human waste: 35 lb; Total: 1400 lb.”
System Power: “Electric”
Annual Energy Use: “Septic Pump: 734 kWh; Greywater and Human Waste: 325 kWh.” In this case, the amount of energy saved by the greywater and human waste systems from the septic use (either by actual measurement or estimation) is listed.
eCO ₂ per Energy Unit: “1.656 lb/kWh”
% of Fuel from ≤10 mi: “31%” from greywater and human waste 325 kWh divided by total (734 + 325 kWh).
Annual Local eCO ₂ : “544 lb” from 1059 × 1.656 × 0.31, giving lifetime of “10,880 lb.”
Annual Distant eCO ₂ : “1210 lb” from 1409 × 1.656 × 0.77, giving lifetime of “24,200 lb.”
Lifetime Total eCO ₂ : “36,480 lb” from adding last two values plus embodied emissions of system.
Local eCO ₂ Percent: “30%” by dividing lifetime local emissions (10,880 lb) by total lifetime (24,200 lb) and multiplying by 100. This could be improved by diverting more from the septic system or installing solar panels to power the system. Or the intrepid could invent a wind-powered septic system.
Electricity
By this point, the majority of the form is clear from previous sections. The only difference is that a large generating system could produce more than 100 percent local power. See the above instructions for heating and cooling to fill out this section. What follows is electric-system-specific changes and an example.
Electric System(s): We’ll use the example of: “6.2 kWp PV solar system with grid tie.”
Power Source(s): “Solar PV and grid.” May also include wind, microhydro, or other sources.
System Embodied eCO₂: “PV System 16,128 lb.” We used the average figure of 2,560 kg CO2e per kWp, but individual systems will vary.
Energy Audited: If the system also powers other utilities audited above, those emissions have already been expressed in a percentage and can be removed from this equation, if desired. For example, the 4 MWh of power for the heating system from the above example (PV: 1 MWh; grid 3MWh) could be subtracted from annual use. “Grand Total” refers to all electrical use for the building. “Energy Deducted . . . ” removes the indicated systems’ energy use and this measure now indicates other electrical use (e.g., typical household appliances, etc.). For this example, we are using the grand total, but note that removing the heating, water, and sewage emissions from the above examples (ca. PV: 1 MWh; grid: 4 MWh), would increase our score in this measure to 70 percent local emissions for household electric use.
Annual Energy Use: “PV system: 5.38 MWh; grid: 6.06; total: 11.44 MWh.”
eCO ₂ per Energy Unit: “1656 lb/MWh”
% of Fuel from ≤10 mi: “47%” from PV system’s 5.38 MWh divided by total (11.4 MWh).
Annual Local eCO ₂ : “8904 lb” from 11.44 MWh × 1656 lb/MWh × 0.47, giving lifetime of “178,080 lb.”
Annual Distant eCO ₂ : “10,041 lb” from 11.44 MWh × 1656 lb/MWh × 0.53, giving lifetime of “200,820 lb.”
Lifetime Total eCO ₂ : “395,028 lb” from adding last two values plus embodied emissions of system.
Local eCO ₂ Percent: “45%” by dividing lifetime local emissions (178,080 lb) by total lifetime (395,028 lb) and multiplying by 100. This could be improved by reducing overall energy use, installing more panels, and/or alternative power generation.
Aesthetics and Design
Although each person weighs form and function differently, we have sought to make a quantitative rubric to award qualified letter grades to reflect quality design and beautiful structures. This should be considered garnish on the plate, complementing the substantial main dish of a ten-mile building with a side of utility audit.
The rubric is based on the applicant-defined purpose(s) of the building: the better a structure meets those needs, the higher the grade. The letter grades range from D to A, as described next. To this assessment, particularly beautiful structures will be awarded with a plus, while most will receive no grade. Only those that are poorly finished would receive a minus.
Letter Grade
Type of Structure: In a phrase, describe the type and size of structure. If a residence, note if it is single or multi-family (e.g., “multi-family primary residence,” “single-family vacation cottage”). Offices should include type of business and an idea of size (e.g., “hundred-person insurance office building,” “small bicycle repair shop,” “office for a single dentist”). Similarly, public and utility buildings should indicate type of space and size (e.g., “60,000-ft² grocery store,” “30,000-ft² botanical garden visitor center,” 200-ft² community garden storage shed”).
Primary Purpose: The purpose is key for assessing a letter grade, as the rubric is based on how well a structure meets that purpose. Sometimes, a purpose is simple: “store farm equipment.” Many structures, though, serve a few purposes. These can be given in rank order. The institute intends to build a multi-use structure with the following purposes: 1) provide space for classes and workshops, 2) house the institute office(s), and 3) house the institute workshop and tool library.
Assessment Questions:
Does the building meet its purpose(s)?
1) Just meets purpose, 2) Meets purpose, 3) Easily meets purpose, 4) Exceeds purpose.
This is subjective and both in the opinion of the builder and outside panel (if formal certification is sought). If much work is needed to show that the building meets the purpose, a low score should be considered. If the purpose is effortlessly evident, a higher score is possible.
What is the quality of materials?
1) Materials are sufficient to meet basic standards or code, 2) A few materials are of better quality, 3) Structural and key materials are of high quality and longevity, 4) All or most materials are of high quality and longevity.
For most materials in a project, we have choices among products. Some are better than others and by choosing the best materials we can reasonably obtain, they should last longer and give better service, meaning they need less maintenance and replacement. Even if they are more costly in terms of money or labor up front, they may provide long-term savings when they do not need to be replaced.
What is the quality and integration of utilities?
1) Utilities are sufficient but not linked, 2) Utilities are of good quality and may or may not be linked, 3) Utilities are of better quality and some are linked together to provide some efficiency, 4) Utilities are high quality and linked together to provide more efficiency.
Utilities that are of high quality and work together are long-lasting, efficient, and robust. Like materials, a higher quality appliance should provide less trouble in maintenance and a longer replacement period (meaning less embodied energy needs to be spent overall). By linking systems, energy that would otherwise be wasted can be scavenged for other uses. For example, instead of running both a water heater and air conditioning systems separately, a heat pump can capture heat out of the indoor space and shunt it into the domestic hot water system. At the institute, we have solar hot water panels that provide BTUs to both the domestic hot water system and hydronic heating system. The heating system can be run with PV solar panels, which also power point-of-use water heaters to bump up any low-temp water. This creates redundancies that allows one component to break down and the others to fill the gap while repairs take place.
Design can be described as:
1) borrowed from other structures or concepts without improvement or adaptation for this use, 2) borrowed from other structures or designs and often adapted for this structure, 3) well-adapted from carefully chosen designs and concepts, 4) truly innovative in addition to adapting other designs for this structure.
We need not invent new designs for every structure. We should borrow from the well-designed examples available to us, but not blindly. Structure design, though, should be adapted to its use and location. The more thought is given to choosing an appropriate design, the better a structure will perform. In ideal cases, new concepts will be created that perform well and will be the basis for future structures.
Total Score and Letter Grade: To compute the overall grade, add each of the individual answers above together. That number corresponds to the final letter grade as indicated by the score ranges.
A Grade (15–16 points): Exceeds and Exemplifies Purpose and Design
B Grade (11–14 points): Comfortably Meets Purpose and Design
C Grade (7–10 points: Adequately Meets Purpose and Design
D Grade (4–6 points): Scarcely Meets Purpose and Design
Grade Justification: Applicants should provide sufficient information to support the assigned letter grade. Discuss both the ways in which the structure meets the selected answer for each component above. For a formal certification a panel will examine these answers and may adjust them up or down. Additional pages of photographs, drawings, and information can be attached if needed.
Aesthetics Plus or Minus
Finally we can asses the aesthetics of the project. This is clearly subjective. For a self-certification, the building owner or resident(s) can score a plus on their grade for exceptionally beautiful work. A minus indicates improvements are needed, hasty construction, and minimal finishing. No grade indicates quality work with no obvious faults but no particular attention to appearance beyond finishing. Beauty is in the eye of the beholder for self-certification.
For formal certification, a panel of three judges will score photographs and the narrative justification. Photographs should be clear, shot without a wide-angle lens (unless absolutely necessary and such shots should be labeled). No filters or other “realtor gimmicks” should be used.
In both cases, the form should have a score suggested by the submitter and a justification narrative, with photos or other documentation attached.
The completed form should be submitted electronically to info@lowtechinstitute.org. Questions, concerns, corrections, etc., can also be submitted to that address. Self-certified buildings will be listed on the website, with the structure name, city, and state, and perhaps a photo. Formally certified buildings will also be listed. Formally certified buildings will also, with the permission of the applicant, be featured on the blog and given their own listing page, with more information, photos, etc.