To add to this: for latitudes above approximately 56 deg N, the December solar irradiance on a south wall will generally be less than the June irradiance.
For these higher latitudes the cosine effect is offset by the attenuating effect of a longer optical path through the atmosphere.
Wouter
On 12/07/2010 06:01 PM, cgueymard wrote:
This is exactly what you would expect, at least outside of the Tropical zone. This is because the sun is lower in winter than in summer, and therefore its angle of incidence on a south vertical surface is lower in winter. Hence the direct irradiance component (i.e., DNI multiplied by the cosine of this angle) is much higher in winter. Chris --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "yclmrl" <yucel_meral@...> wrote:Hi there; I made a simple model that has one zone on nothern hemisphere and I simulated it for 21 June and 21 January design days.For output files Energy Plus calculated surface solar incident. But at the south wall in 21 January, surface solar incident is higher than 21 June. Is that possible? meral------------------------------------ Primary EnergyPlus support is found at: http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx The primary EnergyPlus web site is found at: http://www.energyplus.gov The group web site is: http://groups.yahoo.com/group/EnergyPlus_Support/ Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files. EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/EnergyPlus_Support/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/EnergyPlus_Support/join (Yahoo! ID required) <*> To change settings via email: EnergyPlus_Support-digest@xxxxxxxxxxxxxxx EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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