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Weather #

A weather object contains data about environmental conditions at a specific location and is constructed using an EnergyPlus Weather (EPW) file. As the EPW file is parsed, it is used to construct a location and a sun rig as well as luminous efficacies and sky coefficients for each hour of the year. All of which can be accessed from the weather object. The weather object is then subsequently used to create illuminance and irradiance distributions for the hemisphere in sky series and sky instances.

EnergyPlus Weather File#

The EnergyPlus Weather File (EPW) contains data measured at a weather station, normally at an hourly interval. They can be obtained from numerous third party sources and should ideally be located close to the location of the project being analysed.

Luminous Efficacy Model#

Luminous efficacy is the ratio of luminous flux to power. Meaning how efficiently radiant energy is converted into visible light perceived by the human eye. It can be describe using lumen per Watt (lm/W). It is used to convert the irradiance values for the sky into illuminance.

Measured illuminance#

The measured illuminance mode uses the illuminance and irradiance values from the weather file to calculate the luminous efficacy. This method depends on the accuracy of the measurements and requires the weather file to contain both illuminance and irradiance values.

All Weather Efficacy Model#

The All Weather Efficacy Model calculates the luminous efficacy based on solar position and sky conditions. This method depends solely on irradiance values.

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