Hacker News Reader

People in hot climates have been painting their roofs white for many decades.

http://www.pictureninja.com/pages/israel/coastline-of-israel...

http://travelsplendid.com/wp-content/uploads/2010/10/Santori...

In typical northern zones, the daily solar energy delivered in July is about twice that delivered in December. Winter suffers from a combination of oblique angles, shorter days, and more clouds.

If painting white[1] saves you from moving X joules with your air conditioner in July, that will cost you an extra X/2 joules from your heater in December. This is a win until you have many more heating days (without snow cover) than cooling days.

[1] for perfect white and black, reality will be closer together.

Reply on news.ycombinator.com