The chart shows insolation on a vertical wall by hour-of-day for the selected date. The insolation on a vertical wall varies greatly by time-of-day and the orientation of the wall or window.

What does it tell me?

• How the amount and intensity of sunlight varies through the selected day
• At what times during the day a wall or window will receive sunlight
• e.g. Is this room lighter in the morning or the afternoon?

Note: the chart does not account for shade from structures or objects (e.g. buildings or trees) or cloud cover.

Insolation is a measure of the power of sunlight reaching a surface. It is usually given for a period of time, e.g. per hour, per day, per month.

Horizontal insolation is a good measure of the overall sunlight potential for the location. The direction in which you are facing does not affect its value.

Generally, you will see higher 'horizontal' (i.e. flat ground) insolation in summer months, and lower values during winter months. Latitudes closer to the equator and those lying at higher elevations typically see higher insolation values.