House Ventilation – Tropical Patterns

HOUSE VENTILATION – Tropical Patterns

USE VENTILATION RATHER THAN AIR CONDITIONING IN MOST CASES TO ALLOW OCCUPANTS TO ACCLIMATISE TO THE HOT WEATHER
Acclimatisation to heat takes five days and is rapidly lost when sheltering in the cooler air conditioned zones. Natural ventilation combined with acclimatisation is a more appropriate response to general tropical living.

FOR MAIN HABITABLE ROOMS HAVE AT LEAST 2 EXTERIOR WALLS WITH WINDOWS, PREFERABLY OPPOSITE FOR BENEFIT FROM VENTILATION
Cross flow ventilation needs a windward and leeward opening. If these are opposite, cooling breezes are encouraged.

REDUCE INTERNAL OBSTRUCTIONS (WALLS, FURNITURE) TO AIR FLOW
Air flow can be drastically cut by obstructions, so keep them to a minimum.

HIGH CEILINGS FEEL COOLER AS HOT AIR RISES
High ceilings with high ventilation cause passive flow of air for cooling.

USE GLASS WINDOWS SPARINGLY AS THEY ENCOURAGE HEAT BUILD UP
Glass causes interior build up of heat and restriction of airflow. If used, then look to modern glasses that reduce heat build up.

USE HORIZONTAL OR VERTICAL LOUVRES ON OPPOSING WALLS, TO DIRECT AIRFLOW ACROSS THE HOUSE
Louvres are infinitely adjustable so are useful in varying wind according to changing conditions.

USE LOW CEILING FANS TO CREATE BREEZE
Ceiling fans are a cost effective way to cool.

LARGE WINDOWS ENCOURAGE FLOW OF AIR
Large windows allow more air flow. and when fly screened they compensate for 30% loss of airflow. Avoid glass if possible and have wooden storm shutters.

USE OPEN SCREENS THAT ALLOW AIR FLOW RATHER THAN SOLID WALLS
Decorative screens give some privacy but allow natural air flow

USE HIGH VENTS OR VENTILATORS TO INCREASE NATURAL CONVECTION OF AIR
Hot air rises, so having a high outlet means hot air escapes and cool air flows in from below.

USE LOW WINDOWS AND VENTS FOR FULL VENTILATION
Low vents and windows draw in cooler air from just above the ground as hot air rises out through high vents. This causes breezes and cooling, particularly if the house is surrounded by vegetation that cools the air.

USE PORCHES OR VENTILATED COURTYARDS TO COOL INTERIOR ROOMS
Interior rooms in tropics can get overheated due to thermal mass heating. Allow cooling by designing in areas that direct airflow to these rooms.

EXTERIOR WING WALLS CAN BE HANDY TO CATCH BREEZE AND DIRECT INTO WINDOWS. CASEMENT, SIDE OPENING WINDOWS CAN HAVE THE SAME EFFECT
Wind can blow along outside walls without entering rooms. Re­direct breezes into the rooms for maximum cooling effect.

CONSIDERS SHADING THE WHOLE OF THE ROOF WITH A “FLY ROOF”
In extreme open areas with little vegetation a large designed awning across the whole building can shade it and reduce heat loads.

THE IDEAL WINDOW AND VENT SIZE IS 30 40% BY AREA OF THE FLOOR
The maximum inside breeze rate is no more than 40% of outside speed, at total windward and leeward area being 40% of floor area.