| system | initial cost ($ + hrs) / unit | annualized cost ($ + hrs) / unit | sqft building | sqft land | other resources | revenue | market cost | benefits | | ----------------------------------- | ----------------------------- | -------------------------------- | ------------- | --------- | ---------------------------------------- | -------- | ----------- | --------------------------------------------------------------------------- | | Dual-Mode PVC Thermal Mass Climate | $2,850 + 6.75 hrs | $180 + 1.2 hrs | 300 | 0 | Well water, Waste heat, Solar insolation | $0 | $1,200 | Year-round climate control, Low maintenance, Energy efficient, Quick response | #### Assumptions - Room Dimensions: 12 ft x 25 ft x 8 ft (300 sqft) - Temperature Ranges: - Winter: Outdoor 0°F to 40°F, Target Indoor 65°F-72°F - Summer: Outdoor 75°F to 95°F, Target Indoor 68°F-75°F - Heating Requirements: 4,641 BTU/hour at 0°F outside - Cooling Requirements: 3,500 BTU/hour at 95°F outside - Well Water Temperature: 55°F year-round - Hot Water Supply: 120°F max - Number of Pipes per Dwelling: 19 vertically mounted 8-ft pipes - Number of Dwellings: 400 - PVC Pipe Specs: 6-inch diameter, 8-ft height - Water Flow Rate: 2 GPM per pipe during active modes #### Market Solutions $1,200/year Traditional HVAC alternatives per dwelling: - Mini-split heat pump: $800/year - Equipment lease/depreciation: $400 - Electricity costs: $400 - Window AC + Space heaters: $1,200/year - Equipment costs: $300 - Electricity costs: $900 #### Labor 480 Hours/year (community-wide) | Task | Hours/Year | Notes | | ------------------------------ | ---------- | --------------------------------------------------- | | Seasonal Mode Switching | 100 | Spring/Fall transitions for 400 units | | Regular Inspections | 200 | Monthly checks during active seasons | | Condensation Management | 100 | Weekly maintenance during cooling season | | Temperature Monitoring | 40 | System optimization and adjustment | | Emergency Repairs | 40 | Based on 5% annual failure rate | | Total Labor | 480 | 1.2 hours per dwelling per year | #### Operating Costs $72k/year (community-wide) | Component | Annual Cost ($) | Notes | | --------------------------- | --------------- | ---------------------------------------------- | | Pumping Energy | $40,000 | Based on 2 GPM flow rate during operation | | Water Treatment | $15,000 | Conditioning for both hot and cold circuits | | Replacement Parts | $10,000 | Valves, sensors, minor components | | Control System Maintenance | $7,000 | Software updates, sensor calibration | | Total Operating Cost | $72,000 | $180 per dwelling per year | #### Initial Costs $2,850 + 6.75 hrs -> $285 + 0.675 hrs/year (per dwelling) | Component | Initial Cost ($ + hrs) | Lifespan (Years) | Amortized Cost/Year ($ + hrs) | Justification | | ------------------------- | --------------------- | ---------------- | ---------------------------- | ------------------------------------------- | | PVC Pipes (19) | $760 + 1.5 | 10 | $76 + 0.15 | 6-inch diameter, 8-ft pipes | | End Caps & Fittings | $380 + 0.75 | 10 | $38 + 0.075 | Two per pipe plus flow fittings | | Mounting System | $285 + 1.0 | 10 | $28.50 + 0.1 | Brackets and support structure | | Paint & Coating | $95 + 0.5 | 5 | $19 + 0.1 | UV-resistant black paint | | Valving & Control | $850 + 2.0 | 10 | $85 + 0.2 | Mode switching and flow control | | Condensation Management | $480 + 1.0 | 10 | $48 + 0.1 | Drip pans, drainage system | | Total Initial Cost | $2,850 + 6.75 | - | $285 + 0.675 | Per dwelling installation | #### System Outputs | Mode | Outside Temp (°F) | System Capacity (BTU/hr) | Energy Input (kWh/day) | Performance Notes | |---------|------------------|-------------------------|---------------------|-------------------------------------------| | Heating | 0 | 4,800 | 2.1 | Combined solar gain and hot water | | Heating | 20 | 3,600 | 1.8 | Reduced load, lower energy input | | Heating | 40 | 2,400 | 1.2 | Minimal heating needed | | Cooling | 75 | 2,800 | 1.4 | Well water direct cooling | | Cooling | 85 | 3,200 | 1.6 | Increased flow rate needed | | Cooling | 95 | 3,500 | 1.8 | Maximum cooling capacity | #### Design Considerations 1. Thermal Performance - Heat Transfer Rate: 12-15 BTU/hr/ft² of pipe surface - Temperature Differential: Maintains 15-20°F max between pipe surface and room - Response Time: 30-45 minutes to affect room temperature 2. Moisture Management - Cooling Mode: * Condensation Collection: 2-4 gallons/day per dwelling * Drainage System: Gravity-fed to greywater * Humidity Control: 40-60% target range - Heating Mode: * No condensation issues * Monitor wall moisture content 3. Flow Control - Variable speed pumping - Zone control capability - Temperature-based flow modulation - Pressure relief protection 4. Integration Requirements - Well water supply connection - Hot water supply connection - Electrical for pumps/controls - Drainage system connection - Control system network #### Benefits 1. Cost Efficiency - 75% reduction in energy costs vs traditional HVAC - Minimal maintenance requirements - Long system lifespan - Low-cost components 2. Environmental Impact - Uses renewable/waste heat sources - Minimal electrical consumption - No refrigerants - Low embodied energy 3. Comfort - Silent operation - Even heat distribution - Natural humidity management - Quick response time 4. Resilience - Simple, repairable design - Multiple operating modes - Redundant capacity - Local control possible #### Limitations 1. Technical Constraints - Maximum water temperature limits - Condensation management required - Flow rate optimization needed - Temperature stratification possible 2. Operational Requirements - Seasonal mode switching - Regular condensation checks - Temperature monitoring - System balancing #### Innovation Opportunities 1. Control Systems - Smart flow control - Predictive temperature management - Zone optimization - Mobile monitoring 2. Performance Enhancements - Surface treatment improvements - Flow pattern optimization - Heat transfer enhancement - Condensation reduction strategies