Quick start
- Click Use My Location or type your latitude and longitude.
- Adjust the window area, window height, and building orientation if needed (defaults are fine for a first look).
- Hit Analyze Site.
- Read the results below the map and hover over the sun paths to explore time and angle data.
- Download a PNG of the map or a plain-text report when you're done.
🌐 Which way should my windows face?
Northern Hemisphere (latitude > 0°, e.g. USA, Europe, Japan, Hawaii):
the sun always tracks through the southern sky, so south-facing windows (180°) capture the most winter sun. This includes Hawaii at ~21°N — it is firmly in the Northern Hemisphere.
Southern Hemisphere (latitude < 0°, e.g. Australia, South America, South Africa):
the sun tracks through the northern sky, so north-facing windows (0°) are optimal.
The app detects your hemisphere automatically and sets the optimal orientation accordingly.
Inputs explained
- Latitude / Longitude
- Your site's map coordinates. Positive latitude = north of the equator. Negative = south.
- Window Area
- Total area of south-facing (NH) or north-facing (SH) glazing — the windows that are supposed to collect winter sun. Bigger area = more potential heat gain.
- Window Height
- Vertical height of those windows. Used to calculate overhang depth — the roof projection that blocks high summer sun while still letting low winter sun in.
- Main Wall Bearing
- Which compass direction your main solar wall faces, measured clockwise from north. 0° = north, 90° = east, 180° = south, 270° = west. The app compares this to the ideal and tells you how much gain you're losing.
- Tree Height
- Mature height of trees you plan to plant. Used to calculate how far their shadows reach on each solstice and where to position them for maximum benefit.
Results explained
- Passive Solar Gain
- A relative measure of how much winter sunlight energy enters through your glazing at solar noon on the winter solstice. Higher is warmer. The relative gain ratio shows how close your orientation is to the theoretical maximum — 100% means perfectly aligned, 70% means you're losing roughly 30% of potential heat.
- Overhang Depth
-
The range for a horizontal overhang (like an eave) above your solar windows:
Min depth — the shortest overhang that fully shades the window at the peak of summer (high sun angle = short overhang needed).
Max depth — the longest overhang that still lets the full winter sun beam hit the window sill (low sun angle = don't go deeper than this or you block winter sun).
- Sunlight Duration
- Hours of direct sunlight on the summer and winter solstice — useful for planning growing seasons, solar panel sizing, and energy budgets. Polar sites may show polar day or polar night instead of a duration.
- Tree Placement
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Deciduous trees (lose leaves in winter) belong on the side where summer shade is most useful — south and west in the Northern Hemisphere. In winter they're bare, so they don't block the low sun you want inside.
Evergreen trees (keep leaves all year) belong on the side where winter wind usually comes from — north and northwest in the Northern Hemisphere. They act as a windbreak without shading your solar windows.
- Site Map
- Top-down view of your property. North is always at the top. The orange arc is the summer solstice sun path; the blue arc is the winter solstice sun path. The green ring slices show where to plant trees (not shadow shapes). Hover any arc point to see the exact time, altitude, and compass bearing of the sun at that moment.