Hoop House Calculator
Estimate greenhouse cover area, conductive heat loss, heater capacity, and covering cost from one consistent geometry model.
Greenhouse inputs
Live results
Surface-area breakdown
| Component | Quantity | Area per component | Total area |
|---|---|---|---|
| Sidewalls | 2 | 75.00 m² | 150.00 m² |
| End walls | 2 | 70.00 m² | 140.00 m² |
| Roof slopes | 2 | 47.17 m² | 94.34 m² |
How to use the hoop house calculator
What this calculator does. It estimates the exposed covering area of a gable, Quonset, arched-sidewall, or lean-to greenhouse, then applies a steady-state conduction model to estimate heat loss, required heater input capacity, and cover-material cost. It is useful for early planning, comparing shapes, checking a supplier quote, and forming a preliminary heater specification. It does not size ventilation, infiltration, solar gain, thermal storage, snow loads, framing, foundations, or a final code-compliant heating system.
When to use it. Use it when laying out a new hoop house, replacing a damaged cover, comparing single- and double-layer glazing, or estimating the heat required on a chosen outdoor design day. For final equipment selection, verify dimensions and thermal properties with product documentation and a qualified designer.
How to calculate. The calculator opens with a complete gable-house demonstration and a validated Excel workbook ready to download. (1) Select Greenhouse type. (2) Replace the visible dimensions with measured outside dimensions in meters. (3) Select Covering material, or choose Custom coefficient and enter a documented Heat loss coefficient (U). (4) Enter Inside temperature, Outside temperature, Heater efficiency, and Material price per unit area. (5) Read the live results and surface-area table. (6) Download the current model as an XLSX workbook. Reset clears the demonstration values and results; Download Excel then stays disabled until a complete valid state is entered again.
Input guide. Greenhouse type is required and controls the geometric formula. Height of sidewalls (H₁) and Gable height (H₂) are positive meter values used for a gable; H₁ also applies to an arched roof with sidewalls. A realistic example is 7.5 m and 2.5 m. Low wall height and High wall height are required only for a lean-to; the high wall cannot be lower than the low wall. Total width (W) and Length (L) are always required positive meter values; 8 m by 10 m is the startup example. Avoid entering interior growing-bed dimensions because the covering follows the exterior envelope.
Covering material supplies a representative U-value. The Heat loss coefficient (U) is measured in W/(m²·K), must be greater than zero, and directly scales heat loss: doubling U doubles the conductive load. Treat preset values as planning assumptions and replace them with tested product data when available. Inside temperature and Outside temperature accept ordinary decimal Celsius values. Their difference drives heat loss; if outside temperature is at or above the inside setpoint, the heating load is zero. NIST explains why a Celsius temperature interval has the same magnitude as a kelvin interval in its SI temperature guidance.
Heater efficiency is a required decimal greater than 0 and at most 1; enter 0.8 for 80%, not 80. Lower efficiency increases the required input capacity because more supplied energy is lost. Material price per unit area is a nonnegative U.S.-dollar amount per square meter. It affects only Material cost, not area or heating load.
Output guide. Surface area is the exact modeled exterior cover area excluding the floor. Conductive heat loss is U × area × positive temperature difference, shown in kW. Heater capacity needed divides conductive loss by efficiency and is a preliminary input-capacity estimate. Material cost equals area times unit price. Temperature difference is the nonnegative heating-design difference. The table lists each geometric component, its count, area per component, and total area; those rows sum to the displayed surface area.
Worked example. The startup gable has 7.5 m sidewalls, a 2.5 m gable rise, 8 m width, and 10 m length. Its two sidewalls total 150.00 m², two end walls total 140.00 m², and two sloped roof panels total 94.34 m², giving 384.34 m². With U = 6.525 W/(m²·K) and a 20 °C temperature difference, conductive heat loss is 50.16 kW. Dividing by 0.80 efficiency gives a heater capacity of 62.70 kW. At $0.50/m², the cover-only material estimate is $192.17. For unit context, NIST identifies the square meter as the SI derived unit of area in its area measurement guide.
How the model works
Each greenhouse shape is decomposed into ordinary surfaces. A gable combines rectangles and triangles with two sloped roof panels. A Quonset is modeled as a half-cylinder with two semicircular ends. An arched-sidewall house adds vertical walls beneath a half-cylinder roof. A lean-to uses a sloped rectangular roof and trapezoidal end walls. The heating calculation is a steady-state envelope estimate, Q = U × A × ΔT. Real installations can require additional capacity for air leakage, wind, doors, ground-edge losses, warm-up time, and design margin.
Planning cautions
Cover purchases commonly need extra material for overlaps, end-wall attachment, repairs, and installation waste. Heater nameplate capacity also depends on fuel type, altitude, venting, controls, and local safety rules. Treat this calculator as a transparent planning model rather than a substitute for product engineering. The U.S. Department of Energy discusses how insulation reduces heat flow in its insulation overview.