Seattle
Winter angle: 59.6°; year-round: 47.6°.
Face glazing south. Winter light is limited, so prioritize clear glazing, shade removal, and condensation control.
Greenhouse Roof Angle Calculator for Winter Sun and Latitude
Find the optimal greenhouse glazing or roof pitch for winter heat gain, year-round growing, or seasonal production from a real location, latitude, and build constraints.
Location & Design Inputs
Use lookup for convenience, current location for your browser position, or open manual coordinates below.
Manual coordinates
Results
Recommended greenhouse roof angle
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Enter a location or latitude to calculate winter, seasonal, and year-round pitch.
Latitude used:—
Face glazing:—
Complement from vertical:—
Pitch ratio:—
Build guidance
Results will flag winter performance, summer overheating risk, framing practicality, and structural review triggers.
Rule of thumb: winter = absolute latitude + about 12 degrees, spring/fall = absolute latitude - about 5 degrees, summer = absolute latitude - about 15 degrees, year-round = absolute latitude.
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Seasonal Greenhouse Roof Angles
| Priority | Angle from horizontal | Angle from vertical | Pitch ratio | Recommendation |
|---|
Angles are fixed-roof planning targets. Adjustable greenhouses can use steeper winter settings and flatter summer settings.
Sun Path Visualization
The diagram shows an equator-facing greenhouse glazing plane against simplified winter, equinox, and summer noon sun paths. The black roof line updates to the selected priority.
Enter a latitude to show hemisphere and ridge guidance.
Monthly Angle Table
| Month | Approx. noon sun altitude | Suggested glazing angle | Planning note |
|---|
Greenhouse Orientation and Roof Angle Guidance
The amount of light that enters a greenhouse depends on how directly sunlight strikes the glazing surface. Winter production usually needs a steeper roof or glazing plane because the sun stays low. Year-round growing usually stays closer to latitude, while summer-focused designs can be flatter and may need shade or ventilation to avoid overheating.
Orientation matters as much as pitch. In the northern hemisphere, the main sun-facing glazing should face south. In the southern hemisphere, it should face north. An east-west ridge often gives the strongest equator-facing roof plane for winter collection; a north-south ridge can spread light more evenly through the day but may create more seasonal variation. Lean-to greenhouses should place the glazed face toward the equator when the site allows it.
Roof angle is only one part of greenhouse design. Structural loads, snow shedding, wind exposure, frame height, glazing material, gutters, vents, and shading all affect the final pitch. Use the result as a solar target, then confirm the build with local code, manufacturer span tables, or structural guidance.
Methodology and Limits
Updated: June 29, 2026.
Local calculation: roof pitch, seasonal tables, orientation guidance, and warnings are computed in your browser. Address lookup and current location are only used when you choose those controls.
Assumptions: fixed-roof recommendations use latitude-based greenhouse rules of thumb and approximate solar-position concepts: latitude, solar declination, and noon solar altitude.
Limit: this is solar and planning guidance, not structural engineering. Heavy snow, high wind, tall walls, unusual glazing, or public/commercial builds should be reviewed against local requirements.
Formula and Solar Geometry
For fixed greenhouse pitch, the calculator starts with rule-of-thumb formulas: winter = absolute latitude + 12°, spring/fall = absolute latitude - 5°, summer = absolute latitude - 15°, and year-round = absolute latitude. Results are clamped to practical 0-90° bounds and then interpreted against the selected constraints.
The monthly table uses the standard solar-position idea that approximate noon sun altitude is 90° - |latitude - solar declination|. Solar declination is near +23.4° in the June solstice, near -23.4° in the December solstice, and near 0° at the equinoxes. The suggested glazing angle is the complement of noon altitude, adjusted for a practical fixed greenhouse surface. This follows NOAA/NREL-style solar-position concepts but remains an approximation for design planning rather than a full minute-by-minute solar calculator.
Worked Examples by Place
Denver
Winter angle: 51.7°; year-round: 39.7°.
Face glazing south. Strong winter sun makes the roof angle useful, but snow and wind checks still matter.
Chicago
Winter angle: 53.9°; year-round: 41.9°.
Face glazing south. A winter-biased pitch helps, while vents and shade cloth can manage summer heat.
London
Winter angle: 63.5°; year-round: 51.5°.
Face glazing south. The winter target is steep, so many builds compromise near year-round pitch.
Melbourne
Winter angle: 49.8°; year-round: 37.8°.
Face glazing north. Summer heat control is often as important as winter solar gain.
Toronto
Winter angle: 55.7°; year-round: 43.7°.
Face glazing south. Snow shedding and structure should be part of the final pitch decision.
FAQs
What is the best greenhouse roof angle for winter sun?
A practical winter greenhouse target is usually absolute latitude plus about 12 degrees, capped at a buildable steep pitch. This favors low winter sun and heat gain.
What roof pitch should I use by latitude?
Use absolute latitude for year-round balance, latitude plus about 12 degrees for winter, latitude minus about 5 degrees for spring and fall, and latitude minus about 15 degrees for summer shade control.
Should I optimize for light or snow shedding?
Winter light and snow shedding both favor steeper roofs, but heavy snow, high wind, or tall framing should be checked against local structural requirements.
How does glazing material affect the angle?
Glass and rigid polycarbonate can tolerate steeper fixed glazing better than low-cost film. Film tunnels and hoop houses often use the result as an orientation and seasonal target rather than an exact roof pitch.
What should I do near the equator or at high latitudes?
Near the equator, small roof angles may be impractical, so drainage and ventilation often set the minimum pitch. At high latitudes, winter targets can become very steep and may need structural review or supplemental light.
Can a hoop house use this calculator?
Yes, but treat the number as the best-facing tangent or glazing zone rather than a single flat roof angle because a hoop has many angles across its curve.
How much does a few degrees of error matter?
A few degrees usually matter less than shade, orientation, dirty glazing, and structural constraints. Being within about 5 degrees of the target is typically acceptable for fixed greenhouse planning.
Are results private?
The roof angle calculations run locally in your browser. Address lookup and current location are only used when you choose those buttons.
How it works
Use a city, ZIP, current location, or manual coordinates to compare greenhouse roof pitch recommendations for winter sun, seasonal production, and year-round growing.
- Enter a location: Search for a city, address, or ZIP code, use current location, or enter latitude and longitude manually.
- Choose greenhouse priorities: Select the production priority, greenhouse style, ridge direction, glazing material, snow load priority, wind exposure, and any existing pitch.
- Calculate roof angles: Click Calculate to view winter, spring/fall, summer, and year-round roof angles with vertical complements and pitch ratios.
- Review orientation and constraints: Use the recommendation panel, sun-path diagram, monthly table, and orientation notes before final structural design.
5 Fun Facts about Greenhouse Angles
Sun angle swings 47°
The sun’s apparent declination shifts about ±23.4° through the year.
Astronomy
Steeper roofs shed snow
A higher pitch helps snow slide off, reducing load on the structure.
Structure
Orientation is critical
In the northern hemisphere, glazing faces south for maximum sun.
Orientation
Diffuse light still counts
Cloudy days deliver diffuse photons that still support photosynthesis.
Light quality
Winter crops need every photon
Low sun angles and short days make roof angle especially important in winter.
Seasonal
Disclaimer
This tool provides solar guidance only. Always verify structural requirements for snow, wind, and local building codes.