| system | initial cost ($ + hrs) / unit | annualized cost ($ + hrs) / unit | sqft building | acre land | revenue | market cost | benefits | | --------- | ----------------------------- | -------------------------------- | ------------- | --------- | ------- | ----------- | ----------------------------------------------------- | | Snow Melt | $930k + 4200 hrs | $262k + 3280 hrs | 600 | 0.75 | $0 | $780k | Year-round accessibility, safety, reduced maintenance | #### Assumptions - Coverage: 62,000 sqft total heated area - Primary: 1,400 ft × 20 ft = 28,000 sqft - Secondary: 2,000 ft × 12 ft = 24,000 sqft - Tertiary: Selected 10,000 sqft of critical connections - Grand Rapids climate: - 65 snow days/year - 390 operating hours/year - Average snow event temp: 25°F - Internal resource costs: - Geothermal heat: $0.02/kWh equivalent - Power for pumps/controls: $0.08/kWh - Glycol solution: $2/gallon #### Thermal Requirements - Heat load: 100 BTU/sqft/hr during snow melting - System total: 6.2M BTU/hr at full operation - Geothermal supply: 55°F source temp - Heat pump output: 130°F max - Supply temp: 120-130°F - Return temp: 90-100°F - Efficiency: 3.5-4.0 COP #### Operating Parameters | Parameter | Value | Source/Notes | |-----------|--------|-------------| | Flow Rate | 2.5 GPM/1000 sqft | Engineering standard | | Total Flow | 155 GPM | At full system operation | | Pump Power | 25 HP total | Split across 6 stations | | Response Time | 20-30 min | From cold start to full melt | | Glycol Mix | 30% | Freeze protection to -20°F | #### Initial Costs $930k + 4200 hrs -> $152k + 680 hrs/year | Component | Initial Cost ($ + hrs) | Lifespan (Years) | Annual Cost ($ + hrs) | Notes | |-----------|------------------------|------------------|----------------------|--------| | PEX Tubing | $280k + 1200 hrs | 25 | $11.2k + 48 hrs | 1/2" tubes, 6" spacing | | Heat Pumps | $360k + 1000 hrs | 15 | $24k + 67 hrs | 6 stations × 100 ton each | | Manifolds/Controls | $150k + 1000 hrs | 15 | $10k + 67 hrs | Zone control systems | | Circulation System | $100k + 600 hrs | 10 | $10k + 60 hrs | Pumps, exchangers | | Distribution | $40k + 400 hrs | 25 | $1.6k + 16 hrs | Headers, valves | #### Operating Costs $110k/year | Component | Cost/Year | Notes | |-----------|-----------|--------| | Heat Pump Power | $65k | Based on 390 operating hours | | Pump Power | $25k | Includes distribution pumps | | Glycol Replacement | $12k | 20% annual replacement | | Controls/Sensors | $8k | Calibration, replacement | #### Labor 2600 Hours/year | Task | Hours/Year | Skill Level | Notes | |------|------------|-------------|--------| | System Monitoring | 975 | Support | During snow events | | Maintenance | 650 | Standard | Weekly checks | | Emergency Response | 650 | Expert | On-call coverage | | Controls/Programming | 325 | Expert | Optimization | #### Geothermal Integration - Source temp: 55°F constant - Heat pump COP: 3.5-4.0 - Power input: 440 kW total - Heat output: 6.2M BTU/hr - Well depth: 400-500 ft - Wells needed: 12-15 - Field size: 0.75 acre #### Station Layout 1. Central Hub Station (150 tons) - Serves central facilities - Highest priority paths - 3 wells, 125 GPM capacity 2-3. Primary Path Stations (100 tons each) - Cover main arteries - 2-3 wells each - 80 GPM capacity each 4-6. Secondary/Tertiary Stations (100 tons each) - Zoned coverage of housing clusters - 2 wells each - 60 GPM capacity each #### Critical Success Metrics - Snow-free response time < 30 minutes - Operating cost < $2/sqft/year - System reliability > 99.9% - Zone control granularity < 2000 sqft