- earth bag: ~14" wide × 6" high x 24" long, ~0.037 cubic yards of soil - so 2 linear feet (24") of wall that is 14" wide and 8' tall would take 16 earth bags ~ .3cubic yard soil / foot 8' earth wall - 10 acres, 25ft deep ~400k cubic yard | **Construction Technique** | **Description** | **Labor Cost (hrs/linear ft)** | **Material Cost ($/linear ft)** | **Pros** | **Cons** | | ---------------------------------- | ----------------------------------------------------------------------------- | ------------------------------ | ------------------------------- | -------------------------------------------------------- | ------------------------------------------------------ | | **Wood Frame (Stud Wall)** | Traditional framing with wooden studs and sheathing. | 2-3 hrs | $4-$6 | Fast construction, flexible, widely available materials | Susceptible to moisture damage, less energy efficient | | **Steel Frame** | Metal studs and framing, often used in commercial builds. | 3-4 hrs | $5-$8 | Durable, fire-resistant, moisture-resistant | More expensive materials, harder to work with manually | | **Concrete Block (CMU)** | Stacked concrete blocks with mortar. | 4-5 hrs | $8-$12 | Fire-resistant, strong, low maintenance | Heavy, labor-intensive, slower construction | | **ICF (Insulated Concrete Forms)** | Concrete core surrounded by rigid insulation. | 6-8 hrs | $10-$15 | Excellent insulation, energy-efficient, durable | High material cost, complex installation | | **Straw Bale** | Walls made from compacted bales of straw wrapped in plaster. | 4-5 hrs | $3-$5 | Sustainable, great insulation, natural materials | Labor-intensive, not as durable as other options | | **Earthbag** | Walls made from bags filled with earth or sand, often used for natural homes. | 5-6 hrs | $2-$4 | Low cost, sustainable, good thermal mass | Requires skilled labor, moisture concerns | | **Rammed Earth** | Walls built from compacted earth, often mixed with stabilizers. | 8-10 hrs | $6-$8 | Strong, aesthetically pleasing, environmentally friendly | Expensive setup, slow process | | **Wooden Panel (Pre-fab)** | Pre-manufactured panels assembled onsite. | 1-2 hrs | $7-$9 | Quick installation, high precision | Limited customization, transportation costs | | **Cob** | Natural building technique using a mix of clay, sand, and straw. | 10-12 hrs | $1-$3 | Sustainable, great insulation, aesthetic flexibility | Very labor-intensive, requires specialized knowledge | ## Key Metrics $15 + 2 hr / linear foot of wall - Cost per linear foot: $12.36 - Labor hours per linear foot: 1.84 - Material per linear foot: 0.71 cubic yards - Production rate: ~6.25 linear feet per person per day ## Direct Materials | Item | Quantity | Unit Cost | Total Cost | |-------------------|----------|------------|------------| | Polypropylene Bags| 1,600 | $0.35 | $560 | | Barbed Wire | 1,200ft | $0.08/ft | $96 | | Tampers | 2 | $40 | $80 | | Hand Tools | Set | $200 | $200 | | Total Materials | | | $936 | ## Equipment Operation (for 71 cubic yards soil) | Operation | Fuel (gal) | Cost/gal | Total Cost | |-------------------|------------|----------|------------| | Excavation | 24 | $4 | $96 | | Transport | 18 | $4 | $72 | | Screening | 8 | $4 | $32 | | Total Fuel | 50 | | $200 | ## Labor Hours Breakdown | Task | Workers | Hours | Total Hours | Notes | |--------------------------|---------|--------|-------------|--------------------------------| | Site Preparation | 2 | 4 | 8 | Level ground, mark layout | | Soil Excavation | 2 | 8 | 16 | Using small excavator | | Soil Processing | 2 | 6 | 12 | Screening, moisture adjustment | | Bag Filling Station | 4 | 12 | 48 | Assembly line style | | Wall Construction | 6 | 16 | 96 | Laying bags, tamping, wire | | Quality Control | 1 | 4 | 4 | Level checks, supervision | | Total Labor Hours | | | 184 | | ## Summary per 100ft Wall Section - Material Costs: $936 - Fuel Costs: $200 - Equipment Wear: ~$100 - Total Direct Cost: $1,236 - Labor Hours: 184 ## Notes 1. Assumes level ground, good weather conditions 2. Includes 20% material waste factor 3. Based on assembly-line style workflow 4. Excludes equipment purchase/depreciation 5. Assumes soil is suitable (30% clay content) 6. Labor hours include all preparation and finishing work Each earthbag dwelling is a 300 square foot (12' x 25') unit optimized for 2-2.5 residents. The layout emphasizes simplicity and efficiency, with a single interior wall separating the sleeping area from the main living space. A compact utility core combines a 4' x 5' bathroom featuring a composting toilet with an adjacent 5' x 6' kitchenette area with a sink, the only water feature. A minimal kitchenette acknowledges the community's shared dining facilities while still providing for basic food preparation and storage needs. This utility core is positioned along the northern wall, where it helps buffer living spaces from heat loss while consolidating plumbing and mechanical systems. The units are arranged in groups where the full length of north and south 25' walls are shared through a common earthbag wall with the adjacent dwelling. This shared wall significantly reduces material needs and enhances thermal stability between units. The design emphasizes passive solar gain using clerestory windows that enhance natural light penetration and facilitate stack-effect ventilation. The thermal mass of the earthen floor and north wall(s) work in concert with the south-facing clerestory windows to store and release heat in a controlled manner. Each unit connects to a district heating and cooling system through a small but efficient utility room (6' x 4') that houses a heat exchanger, fan coil unit, electrical panel, and plumbing connections. The hydronic system provides supplemental heating and cooling when passive systems aren't sufficient. - all non-adjacent exterior facing walls will have 4in of rigid foam (R-10 per inch) creating R-45 walls - (1) 34"×24" legal egress window in bedroom - This design balances individual comfort with community efficiency, using natural materials and passive systems to create comfortable, low-maintenance homes that require minimal energy input. The shared wall approach not only reduces construction and maintenance costs but also creates a more thermally stable environment for all residents. ### Clerestory Setup - For 6 windows with 2 operable: - 4 fixed windows: $3,680-5,520 - 2 operable windows: $3,850-5,400 - Total system: $7,530-10,920 - Natural stack effect creates passive ventilation. 12 ft height difference generates ~1.8 Pa total pressure - low air intake at door - Area of Windows: 6×24 =144 ft² = 13.378m² - Solar Insolation on Winter Day: 1 kWh/m²/day -> 3,412 BTU - efficiency: 70% (with passive optimization)🤞 - 13.378m² x 3,412 BTU x .7 = 31952 BTU/day - reflector system on adjacent roof might add 50% to the kWh/m²/day - 31952 BTU/day * 1.5 = 47928 BTU/day ### Lifespan-based Cost Analysis: Earthbag Dwelling *analysis based on 600 sq ft dwelling for 2-3 people, cold climate adapted* #### Summary Costs (per Person Based On 2.5 Occupants) | cost | dollars | hours | | -------------------------------- | ------- | ----- | | amortized initial building costs | $212 | 4.16 | | annual maintenance | $124 | 5.60 | | **total** | $336 | 9.76 | #### Amortized Initial Building Costs | component | initial cost ($/hrs) | lifespan | annual cost ($/hrs) | per person ($/hrs) | notes | | ------------------- | -------------------- | -------- | ------------------- | ------------------ | ----------------------------------------------- | | foundation | $1,600/40 | 75 | $21.33/0.53 | $8.53/0.21 | rubble trench, minimal concrete, gravel bed | | earthbag walls | $500/140 | 75 | $6.67/1.87 | $2.67/0.75 | 51% shared walls reduce material needs | | structural frame | $1,200/40 | 50 | $24.00/0.80 | $9.60/0.32 | bond beam, window/door frames, minimal interior | | external insulation | $3,000/30 | 30 | $100.00/1.00 | $40.00/0.40 | rigid insulation, rain screen, shared walls | | roofing system | $3,800/60 | 25 | $152.00/2.40 | $60.80/0.96 | metal roof, clerestory windows, insulation | | windows/doors | $2,400/20 | 30 | $80.00/0.67 | $32.00/0.27 | south-facing thermal windows, insulated doors | | floor system | $600/24 | 30 | $20.00/0.80 | $8.00/0.32 | earthen floor with finish, thermal mass | | plumbing | $400/16 | 30 | $13.33/0.53 | $5.33/0.21 | single sink, composting toilet, minimal runs | | heat exchange | $800/12 | 25 | $32.00/0.48 | $12.80/0.19 | connection to district heating/cooling | | air sealing | $600/12 | 30 | $20.00/0.40 | $8.00/0.16 | envelope sealing, focused on shared walls | | electrical | $400/16 | 30 | $13.33/0.53 | $5.33/0.21 | minimal circuits, shared infrastructure | | finishes | $500/20 | 15 | $33.33/1.33 | $13.33/0.53 | natural plasters, earthen finishes | | **total** | **$15,800/430** | - | **$530/11.34** | **$212/4.16** | efficient design reduces overall costs | #### Annual Maintenance Costs | system | material cost | hours | per person cost | per person hours | notes | | ------------------- | ------------- | ------ | --------------- | ---------------- | -------------------------------------- | | wall maintenance | $25 | 4 | $10 | 1.60 | reduced by shared walls | | roof/windows | $35 | 3 | $14 | 1.20 | including clerestory maintenance | | floor care | $15 | 2 | $6 | 0.80 | annual sealing and repair | | plumbing systems | $20 | 2 | $8 | 0.80 | composting toilet, sink maintenance | | heat exchange | $30 | 1 | $12 | 0.40 | filter changes, annual inspection | | air sealing | $25 | 1 | $10 | 0.40 | annual inspection and repair | | electrical | $20 | 0.5 | $8 | 0.20 | minimal system maintenance | | finish repair | $40 | 2 | $16 | 0.80 | touch-up natural finishes | | district share | $100 | 1 | $40 | 0.40 | share of central system maintenance | | **total** | **$310** | **14** | **$124** | **5.60** | simplified systems reduce maintenance | #### Efficiency Features Of This Design - 51% shared walls reduce material and maintenance - minimal interior walls maximize usable space - passive solar design reduces mechanical needs - district systems reduce individual equipment - simple plumbing reduces maintenance points - natural materials allow easy repairs - shared infrastructure lowers individual costs - compact design maximizes efficiency ### Passive Solar Design - 120 ft² clerestory = >11 m2 of windows - Daily heat gain: ~25-30 kWh - Solar irradiance: ~700 W/m² at noon - total heat loss - Wall (180 ft² @ R-20): ~153 BTU/hr/°F - Windows (120 ft² @ R-3): ~680 BTU/hr/°F - Total loss coefficient: ~833 BTU/hr/°F #### Building Heat Load Analysis - thermal mass to store daytime heat for nighttime use and moderate temperature swings to 65-75°F - base temp: 68 - thermal mass goal to store 100K BTU for winter overnights - house volume - 8' x 12' x 25' (box) = 2400 - 6' x 12' x 25' (right angle roof) = 900 - total = 3300 - .75 ACH | Surface Type | Area (ft²) | R-Value | UA (BTU/hr·°F) | 0° -> 65° BTU | 75° -> 100° BTU | | ------------ | ---------- | ------- | -------------- | ------------- | --------------- | | East Wall | 112 | 45 | 2.49 | 161.85 | 62.25 | | West Wall | 126 | 45 | 2.80 | 182.00 | 70.00 | | Entry Door | 20 | 5 | 4.00 | 260.00 | 100.00 | | Window | 6 | 3 | 2.00 | 130.00 | 50.00 | | Clerestory | 150 | 3 | 50.00 | 3,250.00 | 1,250.00 | | Roof | 336 | 60 | 5.60 | 364.00 | 140.00 | | Floor | 300 | 20 | 15.00 | 975.00 | 375.00 | | South Wall | 200 | 40 | 5.00 | 325.00 | 125.00 | | North Wall | 200 | 40 | 5.00 | 325.00 | 125.00 | | **Total** | **1,150** | - | **91.89** | **5,816.85** | **2,232.25** | | Scenario | Heat Loss (BTU/hr) | Solar Gain (BTU/hr) | Net Load (BTU/hr) | Realistic Indoor Temp¹ | | ------------- | ------------------ | ------------------- | ----------------- | ---------------------- | | -20°F Cloudy | 10,482 | 3,240 | -7,242 | 23°F | | -20°F Average | 10,482 | 6,075 | -4,407 | 40°F | | -20°F Sunny | 10,482 | 16,200 | +5,718 | 85°F² | | 0°F Cloudy | 8,132 | 3,240 | -4,892 | 37°F | | 0°F Average | 8,132 | 6,075 | -2,057 | 55°F | | 0°F Sunny | 8,132 | 16,200 | +8,068 | 88°F² | | 30°F Cloudy | 4,543 | 3,240 | -1,303 | 60°F | | 30°F Average | 4,543 | 6,075 | +1,532 | 78°F | | 30°F Sunny | 4,543 | 16,200 | +11,657 | 90°F² | | Material | Volume Needed | Weight | Location Options | Notes | | ------------------ | ------------- | ---------- | -------------------------------------- | --------------------------------- | | Earth/Sand (walls) | 400 ft³ | 48,000 lbs | Already have 330 ft³ in exterior walls | Need ~70 ft³ additional | | Concrete | 410 ft³ | 61,538 lbs | Floor slab + benches | Too heavy for elevated floor | | Water | 154 ft³ | 9,600 lbs | Storage tanks | Most efficient, needs containment | | Material | Specific Heat (BTU/lb°F) | Density (lb/ft³) | Heat Capacity (BTU/ft³°F) | | --------------------- | ------------------------ | ---------------- | ------------------------- | | Earthbags (soil/sand) | 0.200 | 120 | 24.0 | | Concrete | 0.156 | 150 | 23.4 | | Water | 1.000 | 62.4 | 62.4 | | Earthen Floor | 0.180 | 130 | 23.4 | #### Thermal Mass Calculations | Component | Surface Area (ft²) | Thickness (ft) | Volume (ft³) | Heat Capacity (BTU/ft³°F) | Total Storage (BTU/°F) | Daily Storage (BTU @ 10°F) | | -------------- | ------------------ | -------------- | ------------ | ------------------------- | ---------------------- | -------------------------- | | Earthbag Walls | 592 | 1.25 | 740 | 24.0 | 17,760 | 177,600 | | Earthen Floor | 300 | 0.50 | 150 | 23.4 | 3,510 | 35,100 | | **Total** | | | 890 | | **21,270** | **212,700** | Notes: 1. Walls: Using standard earthbag width of 15 inches (1.25 feet) 2. Floor: Using typical 6-inch (0.5 foot) thick earthen floor 3. Heat Capacity values: - Earthbags (soil/sand): 24.0 BTU/ft³°F - Earthen Floor: 23.4 BTU/ft³°F 4. Daily storage assumes 10°F temperature swing 5. Effective thermal mass depth varies by diurnal cycle - these calculations assume full depth participation This provides significantly more thermal mass than the previous calculation, which better explains the building's ability to maintain stable temperatures. The total thermal storage capacity of 21,270 BTU/°F means that for every degree Fahrenheit change in temperature, the mass can store or release 21,270 BTU of heat energy. ```chart type: line labels: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23] series: - title: Solar Gain (BTU/hr) data: [0, 0, 0, 0, 0, 0, 810, 2430, 4050, 8100, 12150, 14580, 16200, 14580, 12150, 8100, 4050, 2430, 810, 0, 0, 0, 0, 0] - title: Heat Loss (BTU/hr) data: [-5837, -6100, -6300, -6500, -6300, -6100, -5837, -6100, -6300, -7200, -8131, -8500, -8800, -8500, -8131, -7200, -6300, -6100, -5837, -5837, -5837, -5837, -5837, -5837] - title: Net Balance (BTU/hr) data: [-5837, -6100, -6300, -6500, -6300, -6100, -5027, -3670, -2250, 900, 4019, 6080, 7400, 6080, 4019, 900, -2250, -3670, -5027, -5837, -5837, -5837, -5837, -5837] tension: 0.2 legend: true yAxisLabel: BTU/hr fill: false ``` #### Studio - Air filtration loss: .4ACH ##### Envelope Loss | Surface Type | Area (ft²) | R-Value | UA (BTU/hr·°F) | 0° -> 65° BTU | 75° -> 100° BTU | |--------------------|------------|---------|----------------|---------------|-----------------| | Short Wall | 112 | 45 | 2.49 | 161.78 | 62.22 | | Entry Door | 20 | 5 | 4.00 | 260.00 | 100.00 | | Clerestory | 144 | 3 | 48.00 | 3120.00 | 2640.00 | | Clerestory (night) | 144 | 20 | 7.20 | 468.00 | 396.00 | | Roof | 336 | 60 | 5.60 | 364.00 | 140.00 | | Floor | 300 | 20 | 15.00 | 975.00 | 375.00 | | **Day Total** | **912** | - | **75.09** | **4880.78** | **3317.22** | | **Night Total** | **912** | - | **34.89** | **1828.78** | **1073.22** | ##### Total BTU Loss By Hour | Hour | Outside Temp | BTU Lost by Envelope | BTU Lost by Air Infiltration | Total BTU Lost | BTU Absorbed (Clerestory) | Net BTU Change | Cumulative BTU | Inside Temp (°F) | | :--- | :----------- | -------------------: | ---------------------------: | -------------: | ------------------------: | -------------: | -------------: | ---------------: | | 8 | 10.3 | 4332.69 | 1038.6 | 5371.29 | 5325.0 | -46.29 | -46.29 | 68.00 | | 9 | 11.3 | 4257.60 | 1020.6 | 5278.20 | 5325.0 | 46.80 | 0.50 | 68.00 | | 10 | 12.9 | 4137.46 | 991.8 | 5129.26 | 5325.0 | 195.74 | 196.25 | 68.01 | | 11 | 15.0 | 3979.77 | 954.0 | 4933.77 | 5325.0 | 391.23 | 587.48 | 68.03 | | 12 | 17.4 | 3799.55 | 910.8 | 4710.35 | 5325.0 | 614.65 | 1202.12 | 68.06 | | 13 | 20.0 | 3662.47 | 840.0 | 4502.47 | 5325.0 | 822.53 | 2024.65 | 68.10 | | 14 | 22.6 | 3467.31 | 774.0 | 4241.31 | 5325.0 | 1083.69 | 3108.34 | 68.15 | | 15 | 25.0 | 3240.18 | 702.0 | 3942.18 | 5325.0 | 1382.82 | 4491.16 | 68.21 | | 16 | 27.1 | 2973.90 | 624.0 | 3597.90 | 5325.0 | 1727.10 | 6218.26 | 68.29 | | 17 | 28.7 | 2667.81 | 540.0 | 3207.81 | 0.0 | -3207.81 | 3010.45 | 68.14 | | 18 | 29.7 | 2325.66 | 450.0 | 2775.66 | 0.0 | -2775.66 | 234.79 | 68.01 | | 19 | 30.0 | 1952.20 | 354.0 | 2306.20 | 0.0 | -2306.20 | -2071.41 | 67.90 | | 20 | 29.7 | 2325.66 | 450.0 | 2775.66 | 0.0 | -2775.66 | -4847.07 | 67.77 | | 21 | 28.7 | 2667.81 | 540.0 | 3207.81 | 0.0 | -3207.81 | -8054.88 | 67.62 | | 22 | 27.1 | 2973.90 | 624.0 | 3597.90 | 0.0 | -3597.90 | -11652.78 | 67.45 | | 23 | 25.0 | 3240.18 | 702.0 | 3942.18 | 0.0 | -3942.18 | -15594.96 | 67.26 | | 24 | 22.6 | 3467.31 | 774.0 | 4241.31 | 0.0 | -4241.31 | -19836.27 | 67.07 | | 1 | 20.0 | 3662.47 | 840.0 | 4502.47 | 0.0 | -4502.47 | -24338.74 | 66.87 | | 2 | 17.4 | 3799.55 | 910.8 | 4710.35 | 0.0 | -4710.35 | -29049.09 | 66.66 | | 3 | 15.0 | 3979.77 | 954.0 | 4933.77 | 0.0 | -4933.77 | -33982.87 | 66.44 | | 4 | 12.9 | 4137.46 | 991.8 | 5129.26 | 0.0 | -5129.26 | -39112.13 | 66.21 | | 5 | 11.3 | 4257.60 | 1020.6 | 5278.20 | 0.0 | -5278.20 | -44390.33 | 65.96 | | 6 | 10.3 | 4332.69 | 1038.6 | 5371.29 | 0.0 | -5371.29 | -49761.63 | 65.70 | | 7 | 10.0 | 4355.22 | 1044.0 | 5399.22 | 0.0 | -5399.22 | -55160.85 | 65.44 | | **ACH** | **Stabilized CO2 (ppm)** | **Heat Loss w/ Body Heat (BTU/hr)** | **Relative Humidity (%)** | | ------- | ------------------------ | ----------------------------------- | ------------------------- | | 0.1 | ~1000 | ~100 | ~55 | | 0.2 | ~800 | ~200 | ~50 | | 0.3 | ~700 | ~400 | ~45 | | 0.4 | ~655 | ~550 | ~40 | | 0.5 | ~605 | ~690 | ~37 | | 0.75 | ~500 | ~1025 | ~35 | | 1.0 | ~450 | ~1300 | ~34 | temp stabilazes: 59.97°F with min:58.51° and max: 60.25°F