Climate File


Speckel sources weather files from, a free-to-access depository derived from several public sources.

TMYx (Typical Meteorological Year): a dataset representing typical weather patterns over a year. Options for 2021 (2004 - 2018), 2022 (2004 - 2018) 2022 (2007 - 2021) and 2022 are available.

NIWA (National Institute of Water and Atmospheric Research): a dataset for 18 specific locations across New Zealand.

Set a Weather File Course by picking a suitable source from the dropdown menu.

Custom Location

A Custom Location allows the default project location to be overridden. This is useful for setting preferred local climate data when local typography does not represent the default project location.

Set a Custom Location by entering the 'Location' within the input field. This will then provide an override to the project latitude and longitude coordinates.

Ground Surface


Reflectance, in the context of the ground, refers to the fraction of incident solar radiation reflected by the ground surface. This value plays a role in calculations related to solar heat gain, as sunlight that hits the ground can be reflected onto the building and contribute to its heat load. Reflectance values can range from 0 (no reflection) to 1 (total reflection), but typical values for natural ground surfaces are usually less than 0.3.

To account for Reflectance, navigate to 'Modelling', select 'Ground Surface', and locate the 'Reflectance'. Next, select the desired Reflectance.

Temperature Method

The ground temperature plays a role in calculating heat transfer between the building and the ground. This can be important for buildings with basements, ground-source heat pumps, or any other situation where the ground temperature could affect the building's thermal behaviour.

The following Temperature Methods are available:

Fixed Temperature: Assumes a constant temperature across the year.

Weather File: Uses the topmost temperature layer in the EPW weather file.

Monthly Average Drybulb: Calculated from the EPW weather file dry-bulb temperature.

To account for your Temperature Method, navigate to 'Modelling', select 'Ground Surface', and locate the 'Temperature Method'. Next, select the desired Temperature Method.

Last updated