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Thermal Modelling and Intuitive Experience

Passive Design in the Pacific Environment PASSIVE DESIGN FOR THERMAL COMFORT IN A TROPICAL ENVIRONMENT Neil Purdie . Thermal Modelling and Intuitive Experience. Understanding of heat transfer mechanism Predicts internal temperatures Uses real weather data (Guam)

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Thermal Modelling and Intuitive Experience

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  1. Passive Design in the Pacific EnvironmentPASSIVE DESIGN FOR THERMAL COMFORT IN A TROPICAL ENVIRONMENT Neil Purdie

  2. Thermal Modelling and Intuitive Experience • Understanding of heat transfer mechanism • Predicts internal temperatures • Uses real weather data (Guam) • Two software methods (ECOTECT & IES) • Verified by data loggers in Samoa • Actual building Faiaii exceeds predicted performance

  3. Typical P Series Meeting House

  4. The Pacific RegionBetween Tropic of Cancer (20°N ) and Tropic of Capricorn (20°N )

  5. Ocean Surface Temperatures

  6. Wind Speeds

  7. Sustainability vs Sacred Cows: • Comfort Envelope ( what will you accept?) • Natural Ventilation vs Thermal Mass • Ceiling Fans vs Openable Windows • Occupancy (Transient or continuous) • Accurate Modelling of temperatures • Acceptance by occupants of wider envelope

  8. Thermal Comfort Envelopes

  9. P Series P 230 –17SC

  10. Shading of Thermal Mass

  11. Passive Vent provides equilibrium

  12. Effective cooling from fans • Ceiling fans create air movement • Velocity of 2 – 3 m/s • Air movement transfers heat to floor • Air movement cools skin (evaporation) • Combined effect of air movement over skin is a perceived temperature drop of 1C even though air temperature has not dropped.

  13. Effective cooling from fans Ceiling Fan Air Speed = 2 to 3 m/s Heat gain from people Cool Floor

  14. Thermal mass • Heavy weight concrete structure. • Thick concrete slab on grade. • Thick heavyweight concrete block wall. • Slab on grade allows heat to be transferred into ground • Thermal Mass only works if cool. Therefore must be shaded from external gains to be effective.

  15. Internal temperature profiles Shows how internal temperatures vary across a particular day of the year.

  16. Actual Thermal Profile

  17. Outdoor Temperature and Humidity

  18. Indoor Temperature and Humidity(Chapel)

  19. Indoor Temperature and Humidity (Classroom)

  20. Recommendations to maximise thermal comfort • Shaded Thermal Mass • Light coloured insulated roof • Ceiling fans evenly distributed • Internal flow of air for equilibrium • Transient occupancy

  21. Conclusions/ Application to New Zealand • Acceptance of expanded comfort envelope (18C to 26C) • Acceptance of shaded thermal mass ( say NO to glass boxes) • Acceptance of ceiling fans • Heat and cool floor slabs for thermal comfort

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