Internal Conditions
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The default 'Fixed', assumes the indoor temperature is maintained at 20 Β°C.
In cases where internal air conditions are undefined, a simplified method may be applied to estimate internal temperature based on external air temperature. Internal air conditions are sourced from the climate file for the location automatically, providing the daily mean external air temperature applicable to 'Continental' and tropical climates.
Where a more conservative assumption is required associated to the internal temperature, it can be modified under 'Change Temperature', shifting the indoor climate by the stated value. For example, a -2.0 Β°C will modify the climate file for the location, resulting in lower internal temperatures.
The default 'Fixed', assumes the indoor relative humidity is maintained at 70% RH.
In cases where indoor air conditions are undefined, a simplified method may be applied to estimate indoor relative humidity based on external air humidity. The indoor relative humidity level is selected according to the expected occupancy of the building, being either 'Normal occupancy' (A) or 'High occupancy' (B), as per the chart below.
Where a more conservative assumption is required associated to the indoor relative humidity, it can be modified under 'Change Relative Humidity', shifting the indoor climate by the stated value. For example, a +5% will modify the climate file for the location increasing all data points by 5%, resulting in higher indoor relative humidity.
According to A.2 Maritime climates, internal humidity loads are categorised into five humidity classes, as per ISO 13788 Table A.1 β Internal humidity classes. The selected humidity class sets limit values for Ξv (humidity ratio) and Ξp (vapour pressure) based on measurements from buildings in Western Europe. . For calculations, it is recommended to use the upper limit of each class unless the designer can substantiate less severe conditions.
1
Unoccupied buildings, storage of dry goods
Very low
2
Offices, dwellings with normal occupancy and ventilation
Low
3
Buildings with unknown occupancy
Typical
4
Sports halls, kitchens, canteens
High
5
Special buildings, e.g. laundry, brewery, swimming pool
Very high
Where a more conservative assumption is required associated to the indoor relative humidity, it can be modified under 'Change Relative Humidity', shifting the indoor climate by the stated value. For example, a +5% will modify the climate file for the location increasing all data points by 5%, resulting in higher indoor relative humidity.
