The figures are fairly similar between the above collectors, yielding some 4 kWh/day in a temperate climate and some 8 kWh/day in a tropical climate when using a collector with a 2 m2 absorber. In the temperate scenario this is sufficient to heat 200 litres of water by some 17 °C. In the tropical scenario the equivalent heating would be by some 33 °C. Many thermosiphon systems have comparable energy output to equivalent active systems. The efficiency of evacuated tube collectors is somewhat lower than for flat plate collectors because the absorbers are narrower than the tubes and the tubes have space between them, resulting in a significantly larger percentage of inactive overall collector area. Some methods of comparison calculate the efficiency of evacuated tube collectors based on the actual absorber area and not on the space occupied as has been done in the above table. Efficiency is reduced at higher temperatures.