This is how dedicated energy analysis tools such as DOE-2 and EnergyPlus also work – allowing their users to arrange seven daily schedules into a set of characteristic weekly schedules, and then arrange 52 of these weekly schedules over the year. Thus, an ‘average’ year is used, starting and finishing on a Monday. It also presents a problem when designing annual operational or holiday schedules as these would need to be either manually edited to match each test year and locale-specific holiday sequence, or the logic required to apply generic schedules to any particular year and locale would be very complex and extensive indeed. Whilst the effect of this on annual energy use is likely to be quite small, it is an arbitrary and unnecessary variation that may mask other effects that the designer is more interested in. This means that different years may contain a different number of weekends and/or holiday periods and these may occur at slightly different times within each season. For example, the first day of the year in 2010 was a Friday, in 2009 it was a Thursday and in 2008 it was a Tuesday.
![weather file for ecotect weather file for ecotect](http://1.bp.blogspot.com/-c-vCaIab_JU/TgWUzzgyTFI/AAAAAAAAACM/gQwC5FTsPsw/s1600/shadow_0.jpg)
As a year with 365 days does not evenly divide into 52 weeks, each consecutive year starts on a different weekday. The concept of the ‘average’ year is important and needs some explanation. However, because Ecotect does not allow you to enter a year, some people have questioned how accurate it’s solar calculations can be compared to those used by the US National Oceanic and Atmospheric Administration ( NOAA), which do vary slightly from year to year.
![weather file for ecotect weather file for ecotect](https://aecmag.com/wp-content/uploads/2008/02/c_ecotect1.jpg)
In thermal and energy analysis, direct comparability is the most important consideration as the degree of relative change is often far more informative than the quest for absolute accuracy, which is virtually impossible to achieve. Instead, they are designed to replicate as accurately as possible the conditions within a long-term ‘average’ year for use in comparative analysis. Solar calculations in Ecotect, like most energy analysis tools, are not designed to accurately replicate the position of the Sun in the sky and it’s radiative output during any specific year. This article has permanently moved here from the Natural Frequency Journal, though you can still view a