Passive cooling for Queensland custom homes

Air-conditioning is part of contemporary Queensland life. It is a poor substitute for a house that never tried. Passive cooling is the old craft: put the rooms where the air is, keep the sun off the glass, let the night do some work, and give people a fan they will actually switch on.

The Cairns practice that once occupied this domain talked about incorporating tropical surroundings. Surroundings are shade, humidity and a breeze that may smell like the tide. Design for those, and the mechanical system becomes a back-up, not a personality.

Orientation without folklore

North is not automatically virtuous in the wet tropics. A west wall of glass is almost always a mistake from the Gold Coast to Cooktown. A south room can be a gift or a mould farm depending on overhangs and the neighbour.

Walk the block at 8 am and 4 pm. Note the neighbour’s two-storey wall. Note the hill. Note whether the “breeze” is a real corridor or a story the selling agent liked.

Then draw the living room and the outdoor room on the kind side. Indoor-outdoor. Put garages, laundries and the second bathroom on the cruel side if you can.

Shade is a structure

Eaves, verandahs, screens, pergolas with a known summer angle, and external blinds are building elements. Internal curtains are a last resort that heat up before they help.

A verandah that is deep enough to be a room is also deep enough to be shade. That is why the Queenslander still lectures us. Queenslander architecture.

Light roofs, ventilated roof spaces and a ceiling that is not a frying pan belong with insulation and NatHERS.

Breeze paths you can point at

A path needs two openings, a reason for air to move, and not too much furniture in the throat. Security and insects complicate this; design screens and locks so the path can exist at 11 pm.

Breezeways, operable walls, and a plan that is not a deep square all help. Open-plan can serve air or block it with an island. Zoning.

In a cyclone region the same openings are a debris and rating problem. Do not invent a wall of louvres the engineer has not met. Cyclone homes.

Water and night

A house that cannot dump its heat at night will start Wednesday already tired. Lightweight rooms that open, and heavier floors that are shaded, are a pairing. Do not put thermal mass in a sun-soaked glass box and call it “sustainable”.

Ceiling fans are the most cost-effective comfort machine in the state. Specify them in the contract. Put the control where a human reaches it.

A one-page test

Night air, security and the real Queensland dilemma

The best cooling is often the 2 am southerly or the late sea breeze. The best burglary is also a wide-open house. Design locks and screens that let a sash stay open a safe amount. A custom home that can only cool when it is insecure will be shut, and then it will be hot.

Insects are part of the same dilemma. A breeze path through an unscreened kitchen is a theory. Specify the screen as architecture.

Landscaping as a slow eave

A deciduous idea that works in Melbourne is a confused idea in much of Queensland. Choose trees for filtered light and for what they drop. Keep them off the BAL underside and out of the footing moisture zone. Foundations, bushfire.

A pergola with a vine you will actually prune can be a cheaper western shade than a high-performance glass invoice. Only if you will prune.

If you cannot explain, on a single section, how summer sun misses the glass and how a breeze crosses the living room, the design is still a mood board. Send it back. The weather will not grade on a curve.

Fans, night flush and the discipline of switching off

Ceiling fans only work if people use them before they reach for the air-conditioning. Put controls at the door. Specify a speed that is not a helicopter. In bedrooms, a quiet fan is a relationship-saving device.

A night flush — opening the house when the air finally drops — needs screens and a security story. Design both or it will not happen.

Landscaping should not block the breeze path you drew. A feature hedge in the throat of the plan is a redesign.

Measuring the shade you think you bought

On a clear December day, photograph the glass hourly. If the sun is on the floor, the eave is a decoration. Fix it with an external device before you buy heavier glass. The photograph is the consultant.

Cross-ventilation you can point at on plan

Draw arrows. If you cannot, there is no path. Two openings, a throat that is not an island, and screens that can stay shut to insects while remaining open to air. That is the whole machine. Add trees as a bonus. Add air-conditioning as a servant. Do not reverse the hierarchy or February will invoice you weekly, in power and in sleep, until you put the arrows back where the climate asked them to go in the first sketch. Put a thermometer in the unshaded car and another in the planned living room on a sketch day if the old house still stands. The difference is the brief. Design to close that gap with eaves and air, not only with a larger compressor that will drone through every still night from November to March. Draw the arrows on the plan tonight. If you cannot, the breeze is still a story, and stories do not drop the temperature at 3 pm when the west wall is already ringing like a stove.

Draw arrows for the breeze and a section for December sun. If either drawing is missing, you have a mood board. Put fan controls at the door, screens on the path, and trees where they will not block the throat. Air-conditioning can be a servant. It is a poor god. February will invoice you weekly until the arrows and the eaves are back where the climate asked them to go.