Tropical climates are generally characterised by hot, wet summers, high levels of humidity and little change between day and night temperatures. Movement of air is an important strategy for cooling people down, because the body has more difficulty cooling itself with sweat in humid climates. The most important passive design strategy in the tropics is to open up houses as much as possible, even during the heat of the day, to achieve maximum cross ventilation and convective air flow.

The use of lightweight materials for the walls and roof is recommended because they do not store much heat and shed heat quickly, even with small changes in temperatures. Heavy mass products, such as brick and block, will re-radiate the heat they have stored during the day, which keeps the house hot after sunset. When these products are used, it is essential to ensure they are well shaded. Regardless of the construction materials, windows need to be shaded from the sun and protected from rain.

• No ceiling insulation

Ensure

• B8.2.1.

  the orientation of the house is clearly shown on the drawings

• B8.2.2.

  the roof and/or ceiling is insulated

• B8.2.3.

  the roof space is vented

• B8.2.4.

  there are eaves at least 600mm deep to all walls and as wide as possible for rain protection, including the southern walls, because the sun moves to the southern sky in summer in the tropics

• B8.2.5.

  at least one living room and as many bedrooms as possible, are positioned to catch the prevailing summer cooling breezes

• B8.2.6.

  every living room and bedroom has at least two openings (external or internal) to create breeze paths through the room

• B8.2.7.

  the building is engineered to withstand cyclones.

Consider

• developing a long, thin floor plan with as many rooms as possible having windows or openings on at least two walls to achieve maximum cross-ventilation
• providing windows and openings in internal walls to encourage air flow between rooms and through the house but do not compromise privacy
• providing covered external living areas that are positioned to catch the prevailing breezes in both the wet and dry seasons
• providing a screened ‘sleep out’ style verandah positioned to catch the night-time summer breezes
• using lightweight materials such as a steel or timber stud frame with metal, timber or fibre cement claddings
• if using brick or block, fully shading the eastern and western walls with battens, screens, shade cloth, awnings or spaced trees (dense planting will block breezes)
• insulating the eastern and western walls, and possibly the northern wall
• using lighter, more reflective colours on roofs and walls
• using vented ridges or ‘whirly-bird’ ventilators
• raising the ceiling height to greater than 2700mm or using sloping ceilings with a minimum height of 2400mm
• choosing windows that catch the breeze and can be left open in wet conditions, such as louvres, casements or awning windows
• using at least some louvre windows, either metal louvres at a low level to admit cool breezes, or glass louvres high above the windows to let out hot air and admit light above the curtained areas
• using opaque glass in windows to reduce the use of curtains which block breezes
• fitting security and insect screens to all doors and windows, so they can be left open to improve air-flow
• using awnings to shade windows and provide rain protection
• putting high level windows or vents in all rooms, to let out the hot air and draw in cooler air (it is important that windows or vents can be closed in storms)
• planting tree varieties with a canopy above window level and little foliage at lower levels to shade the roof, walls and ground around the house, but still allow air flow at house level (the shade will cool down the air that is drawn into the house)
• using grass and ground covers around the house rather than concrete and sealed surfaces that will absorb heat and re-radiate it into the house
• avoiding shrubs and dense planting up to 2100mm high that will block breezes, make internal rooms darker, and provide breeding areas for mosquitoes and other pests
• positioning the kitchen or part of the living room towards the north-east to capture winter sun on cooler mornings
• locating septic disposal trenches down wind of living areas, but in a location that will get sun in the wet season.

• the roof is insulated and vented
  

  When: COMPLETED DESIGN & SPECIFICATION
  AT HANDOVER
  FINAL COMPLETION

• engineer’s certificate is provided, certifying the building has been designed to suit the wind terrain category
  

  When: AT HANDOVER
  FINAL COMPLETION
  TRADE TEST

• eastern and western walls are shaded and insulated if specified in the contract
  

  When: COMPLETED DESIGN & SPECIFICATION
  DURING CONSTRUCTION
  AT HANDOVER
  FINAL COMPLETION

• all windows open and close properly
  

  When: AT HANDOVER
  FINAL COMPLETION

• landscaping includes planting and measures are in place to water and protect the plants to make sure they are properly established.
  

  When: COMPLETED DESIGN & SPECIFICATION
  AT HANDOVER
  FINAL COMPLETION

As part of cyclical maintenance and to sustain thermal performance:

• clean insect screens to improve ventilation through windows
  

  Who : Local Maintenance Team

  When : 6 Months

• maintain planting and thin out vegetation to maintain airflow
  

  Who : Local Maintenance Team

  When : 12 Months

• repair or replace shade cloths and other screens
  

  Who : Carpenter, Local Maintenance Team

  When : 24 Months

• clean the roof so that the build up of dust and mould does not reduce reflectivity (the amount of heat the roof can reflect), and therefore reduce temperatures inside the house.
  

  Who : Local Maintenance Team

  When : 12 Months

• insulating and venting all roofs
  

  Who : Carpenter, Housing Management

  When : 24 Months

• fixing awnings, verandahs or other shade devices to northern, eastern and western walls
  

  Who : Carpenter, Housing Management

  When : 24 Months

• installing more and/or bigger windows
  

  Who : Carpenter, Housing Management

  When : 24 Months

• knocking out openings internally to improve cross ventilation
  

  Who : Carpenter, Housing Management

  When : 24 Months

• installing high level vents in rooms.
  

  Who : Carpenter, Housing Management

  When : 24 Months

Reardon, C. and Marker, A. 2002, Your Home Guide, Passive Cooling; Institute for Sustainable Futures, University of Technology, Sydney - https://www.yourhome.gov.au/passive-design/passive-cooling

https://www.yourhome.gov.au/passive-design/shading

https://www.yourhome.gov.au/case-studies/hot-humid