Example Data Table
| Input |
Example Value |
Meaning |
| Cover area |
420 m² |
Total heat loss surface area. |
| U-value |
3.2 W/m²K |
Greenhouse cover heat transfer rate. |
| Pipe output |
18 W/m |
Heat available from each meter of buried pipe. |
| Loop limit |
120 m |
Maximum pipe length in one parallel loop. |
| Voltage |
230 V |
Electrical supply used for pump current. |
Formula Used
Conductive loss: Qc = A × U × ΔT
Ventilation loss: Qv = 0.33 × V × ACH × ΔT
Design heat: Qd = (Qc + Qv) × (1 + safety factor)
Corrected pipe rate: R = base pipe rate × ((soil temperature − minimum fluid temperature) ÷ 10)
Pipe length: L = Qd ÷ R
Loop count: N = ceiling(L ÷ maximum loop length)
Flow: m = Qd ÷ (Cp × fluid ΔT)
Head loss: Hf = f × (L ÷ D) × (v² ÷ 2g)
Pump watts: Wp = ρ × g × flow × total head ÷ pump efficiency
Current: A = pump watts ÷ system voltage
How to Use This Calculator
Enter the greenhouse cover area, U-value, target temperature, and outdoor design temperature. Add air volume and air changes for infiltration loss. Then enter soil temperature, pipe output, pipe diameter, loop limit, pump efficiency, run hours, and electricity cost. Press calculate to see pipe length, loop count, flow, pump power, current, and operating cost. Use CSV or PDF export to save the result.
Why geothermal pipe sizing matters
A geothermal greenhouse pipe layout connects crop demand, soil capacity, water flow, and pump power. Good sizing prevents cold beds, oversized loops, and wasted electricity. The calculator estimates design heat loss first. Then it converts that heat target into buried pipe length, loop count, trench area, circulation flow, pressure loss, pump watts, running current, and energy cost.
Heat load and greenhouse demand
The heat load model uses cover area, insulation value, indoor setpoint, outdoor design temperature, air volume, and air changes per hour. Conductive loss rises when the temperature gap grows. Ventilation loss rises when cold air replaces warm air. A safety factor is then added, because wind, wet soil, crop spacing, and pipe contact can change real performance.
Pipe capacity and loop planning
Pipe output depends on soil temperature and the design fluid temperature. The entered pipe rate is treated as output per meter at a ten degree ground-to-fluid difference. The calculator corrects that rate for the actual temperature difference. Required pipe length is the adjusted heat target divided by corrected pipe output. Maximum loop length sets the number of parallel loops. More loops reduce flow per loop and reduce friction loss.
Flow, head, and electrical power
Water flow is based on heat transfer through the circulating fluid. A smaller fluid temperature drop needs more flow. A larger drop needs less flow, but may reduce emitter performance. The friction estimate uses pipe diameter, roughness, velocity, Reynolds number, and a Darcy friction factor. Added head allows for manifolds, filters, fittings, or a heat exchanger. Pump electrical demand is hydraulic power divided by pump efficiency. Current is pump watts divided by system voltage.
Practical use in projects
Use conservative outdoor design temperatures for winter crops. Enter realistic air changes if doors open often. Keep loop length within common installer limits. Check velocity and head together, not pipe length alone. A longer pipe can still work if loops are balanced and pump energy remains reasonable. Always compare the result with local soil data, greenhouse cover losses, and professional design guidance before purchase. Record chosen assumptions with each export. This makes later revisions easier when fuel prices, crops, soil moisture, trench depth, or winter weather expectations often change.
FAQs
What does this calculator estimate?
It estimates geothermal pipe length, loop count, trench length, field area, flow rate, pressure head, pump watts, current, and energy cost for greenhouse heating support.
Is the pipe length a final design?
No. It is a planning estimate. Soil conductivity, groundwater, pipe depth, installation method, crop needs, and local climate should be checked before construction.
Why is air change rate important?
Air change rate estimates heat lost through leakage and ventilation. Greenhouses with frequent door opening or loose covers need higher values.
What is pipe output in watts per meter?
It is the estimated heat delivered by each meter of buried pipe. The calculator adjusts it using the soil-to-fluid temperature difference.
Why does loop count matter?
Parallel loops reduce flow per loop. This can lower friction loss, improve balancing, and help keep pump power within a practical range.
How is pump current calculated?
The calculator estimates hydraulic power from flow and head. It divides by pump efficiency, then divides pump watts by system voltage.
Can I use glycol instead of water?
Yes, but glycol changes viscosity and heat capacity. Adjust flow and head estimates with supplier data for more accurate pump sizing.
Why export CSV or PDF?
CSV helps spreadsheet review. PDF helps sharing results with growers, installers, engineers, or project owners during planning and costing.