Which way does the sun hit?
In Kuala Lumpur, an east-facing wall and a west-facing wall take exactly the same sun over a year — 901 kWh per square metre each. On the west wall, 779 kWh of it arrives after 3pm. On the east wall, none of it does.
Where the sun rises and sets, over the streets
Drag the pin onto your block. The lines are the compass directions the sun rises and sets on through the year — what sits along them is what stands between your windows and the sun.
The fan spans the whole year in Kuala Lumpur: the sun goes down at 294° in June and 247° in December, so anything standing between those two lines takes the late sun at some point in the year. These are directions, not shadows. A line crossing a tower does not mean the tower has been accounted for — it means the sun goes down behind it.
Sun on each wall, over a year
Energy landing on one square metre of wall, in kilowatt-hours, under a clear sky. This is what “how much sun” actually means: it counts the angle the light strikes at, not merely whether it strikes.
Clear sky, so treat these as a comparison between facings rather than a forecast — Malaysian skies are cloudy and humid, and the real figure is often well under half. Cloud reduces every facing together, so the ranking holds even though the totals do not.
Why hours are the wrong measure
At the March equinox in Kuala Lumpur, several facings take the same number of hours of sun after 3pm. They are nowhere near equivalent, and hours cannot show it.
A south wall is the one to watch in this table. A few degrees off the equator the midday sun is almost directly overhead, so it grazes a vertical wall at a hand's width and lands on the roof instead. South can be lit from dawn to dusk and still take barely any energy, while a west wall is lit half as long and takes several times more, because the low late sun strikes it nearly square on. That is also why the last hour before sunset is the one that heats a room.
The sun through the year in Kuala Lumpur
Every degree on this page is an angle, not a temperature. The height column is how far the sun sits above the horizon — 90° is straight overhead. The bearings are compass directions: 90° is due east, 270° due west. At the equinoxes the sun rises and sets almost exactly east and west everywhere on earth; at the solstices it shifts about 23° either side, and that shift is what puts the late sun onto a north-west wall in June and a south-west one in December. Day length here varies by only about 22 minutes across the whole year. Solar noon is by the clock, and Malaysia keeps one clock from Perlis to Tawau, so it falls about an hour earlier in Sabah than in Kedah, and so does the afternoon sun.
What this cannot tell you
Whether anything is in the way. This is the sun's position, not a shadow map. A tower across the road, a hill, or the block's own wing can take all of the sun described above, and none of it would show here. The map draws the directions so you can look along them yourself; it does not know what it crosses. In Kuala Lumpur there is a map that does: see the shadows here, and drop a pin on your block for its hours of sun and the towers that take the rest.
A shadow map needs the height of every building, and no single open source has them. OpenStreetMap carries a height for 17% of buildings in Georgetown, 14% around Bukit Bintang and 5% in Mont Kiara. The global satellite-derived datasets cover everything but saturate near 100 m — in the one licensed for commercial use, Merdeka 118 reads as 35 m against a real 679 m, and the Twin Towers as 99 m against 452 m. The shadow map gets its towers' heights another way, from the storey counts developers file with KPKT, joined to OpenStreetMap outlines. It covers Malaysia wherever the buildings have been mapped; where they have not, this page is as far as the data goes.
- It describes a direction, not a unit. Two homes on the same facing differ by floor, balcony depth, glass and what is opposite.
- It assumes a flat horizon. A unit facing a hill loses the low sun that matters most.
- It gives energy arriving at the wall, not temperature inside. What that becomes indoors depends on glazing, insulation, shading and how air moves through the home.
- Clear sky throughout. Cloud cuts the totals, and it cuts every facing together.
The arithmetic is standard solar geometry and is checkable: the figures here match published almanac times to the minute in both hemispheres, and the clear-sky model peaks at 953 W/m², against the 1,000 W/m² a solar panel is rated at. See methodology.