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Passive house in warm climates!
January 20, 2017

Passive house in warm climates!

The Passivhaus standard was initially developed for mid and northern European climates but the concept has been proven to work extremely well in hot climates as well. High levels of airtightness and insulation work equally well in protecting buildings from overheating provided there is adequate solar shading in place. The Passivhaus Institute published a detailed study of Passivhaus performance in Southern European climates and found the following:

  • Double glazing is acceptable in more temperate climates
  • Thermal mass and moisture absorbing (hygrothermal) materials gain in importance
  • Movable external shading is essential
  • Maybe need for active cooling and/or dehumidifying
  • Any additional cooling demand ≤ 15 kWh / (m²a)
  • The ground can be used as a heat or cold buffer for tempering the supply air

Where the frequency of internal temperatures above 25° C exceeds 10% of the year additional measures are required to protect against summer overheating. Cross ventilation through open windows and night purge ventilation strategies may also be incorporated as part of the Passivhaus cooling concept when appropriate. Where such strategies are not possible Passivhaus permits 15 kWh/(m²a) of additional cooling energy to be used. Such a small cooling load has proven to be sufficient in almost all cases because the Passivhaus concept is highly effective in reducing unwanted heat gains.

The Passivhaus concept has also been proven to work equally well in the Southern hemisphere. The main difference is the need for north facing glazing rather than south facing glazing as is required in the Northern Hemisphere. Additionally, depending on the latitude and climate, it is likely that external shading will be needed on the north and west facing façades to prevent overheating. A mirroring tool is available from Passipedia which allows Southern Hemisphere climate
data to be correctly entered in to the PHPP model.

Source: “Passivhaus primer: Designer’s guide: A guide for the design team and local authorities” by BRE

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