Verandas, Jalousies, and Trade Winds: The Passive Cooling Playbook I Keep Coming Back To

Air conditioning is easy to specify. It is easy to calculate, easy to price, and easy to explain to a client. Sometimes it is absolutely necessary.

Specifying it too early can hide the heat gains created by the building itself.

When I design in Barbados, I try to work through the island's own cooling playbook before I reach for the mechanical one. The work begins with shade, orientation and operable openings, then follows the path of air through the plan and out at high level.

The remarkable thing is that Barbados has been using versions of these ideas for generations.

Barbados sits within the influence of the northeast trade winds, which help moderate the island's tropical maritime climate. Government and agricultural climate sources describe those winds as persistent through much of the year, with direction predominantly within an easterly to northeasterly arc.

For an architect, the wind is both weather and a valuable free environmental resource.

Traditional Barbadian architecture developed a vocabulary that could take advantage of the island's prevailing breezes: large open verandas, operable shutters, jalousie windows, high ceilings, ventilated gables, deep roof overhangs. I would not claim every historic house was deliberately oriented to the northeast — topography, roads, views and social considerations all interfered. But the vocabulary is unmistakable.

The architecture was not trying to create an indoor environment disconnected from the island. It was trying to make the island's climate more comfortable.

Source: FAO — Barbados climate and trade winds

The first passive-cooling decision happens before the first wall is drawn. We establish the building’s orientation, the direction of the breeze, the afternoon solar exposure and a clear path for air to enter and leave.

The mistake I see too often is treating orientation as a secondary issue. A house gets placed on a site because the driveway works, or because the kitchen looks toward the road, or because the client wants the master bedroom facing the view. Then we spend the next thirty years mechanically correcting the environmental consequences.

I would rather solve as much as possible at the planning stage. The Barbados climate gives us a head start: we know the island has persistent easterly and northeasterly trade winds. The only real question is whether we are designing the building to receive them.

We sometimes misunderstand the veranda. We see lifestyle — a place for a chair, a place for a drink, a place for entertaining. All true. Architecturally, it is doing much more.

Barbadian architectural sources describe large open verandas as a characteristic response to the tropical climate, alongside gable roofs, sash and jalousie windows and decorative fretwork. A deep veranda places a layer of shade between the sun and the building envelope. It creates a cooler transition between inside and outside. It allows windows and doors to stay open while being partly protected from direct sun and driving rain. And it makes outdoor living genuinely usable rather than decorative.

That is my architectural reading of it, not a technical term the original builders would have used. But the best passive design usually works like that: it solves several problems at once.

Reference: Barbados.org — architecture

If a wall spends the whole afternoon absorbing direct solar radiation, we have created a problem before anyone switches on a fan. The same applies to glass: large areas of unshaded glazing can generate significant solar heat gain.

Early in a tropical project, I calculate how much sun can be stopped before it reaches the building. Air-conditioning capacity comes later. That may mean deep roof overhangs, verandas, external screens, shutters, pergolas, planting, or simply better-positioned windows. The exact solution depends on orientation and use.

The jalousie window may be the most underrated piece of vernacular climate technology on this island. Traditional Barbadian architecture incorporated sash and jalousie windows, while open verandas and fretwork helped shade and diffuse light. Historical research into Barbadian houses records wide verandas, jalousied windows, high ventilated gables and tray ceilings among the adaptations that developed in response to the tropical climate.

A jalousie gives occupants a useful range between open and closed. Its angle can admit air, limit rain, control light and preserve some privacy as the weather changes.

The Barbados National Trust's material on Bagatelle Great House documents its timber jalousie windows as an important example of eighteenth-century Barbadian vernacular architecture — which is worth knowing when a client assumes louvres are a stylistic affectation.

Reference: Barbados National Trust — Bagatelle Great House

Modern architecture can reduce the window to a visual device: the bigger the glass, the better the view. In Barbados a window has another job — environmental control.

• How much air enters, and from which direction?
• How much sun enters?
• How much rain enters?
• How much privacy is required?
• Can it be adjusted?
• Can the occupants control it themselves?

That last question matters most. Occupants should be able to open, close and shade the building as conditions change.

One of the things I find fascinating about Barbadian vernacular architecture is how often ornament and environmental performance overlap. Traditional sources describe fretwork around windows and verandas as helping to filter light and rain while creating the decorative character we now read as distinctly Barbadian.

We tend to divide architecture into beautiful and functional. The best vernacular work doesn't always accept that division. The detail can be beautiful because it performs. That is the kind of design I want to bring into contemporary work.

Air movement is not only about bringing cooler air in. It is also about letting warmer air out. That is where ceiling height, high-level openings, ventilated gables and deliberate exhaust paths become useful, and historic research on Barbadian houses records high ventilated gables among the tropical adaptations that developed here.

But there is an important distinction. A high ceiling does not cool a house by itself. It increases the volume of the space and lets warmer air stratify above the occupied zone — which only helps if the rest of the system is working: shade, sized openings, an airflow path, high-level exhaust, and fans where necessary. That is the difference between copying a traditional feature and understanding why it existed.

The Barbadian passive-cooling vocabulary

Three devices, one system: stop the sun, admit the breeze, give the warm air somewhere to leave. Every image here is a photograph of a real Barbadian building, credited and licensed.

This is where passive design becomes economically interesting. If the building reduces the heat entering the occupied space, mechanical systems have less to do. If natural airflow provides comfort for part of the year, cooling does not have to run continuously. If the building is properly shaded, the cooling load falls.

Air conditioning still has a role, after the architecture has reduced avoidable heat gain and made use of natural airflow.

This conversation is no longer only about traditional architecture. Barbados' National Energy Policy 2019–2030 sets out the country's transformational goal of becoming a 100% renewable-energy and carbon-neutral island state by 2030, while explicitly emphasising energy efficiency. And the transition is accelerating.

Solar panels matter. Battery storage matters. Grid modernisation matters. But the cheapest unit of energy is usually the unit a building never needs to consume, and that starts at the design stage.

So when I say “passive first, mechanical second,” I am not romanticising old houses. I am describing a design hierarchy: first reduce the environmental load, then use passive systems, then use efficient mechanical systems to handle whatever remains.

I don't want to romanticise the past either. Traditional houses had limitations. They needed maintenance. They had less control over humidity than a modern conditioned building. They were not designed around today's electrical, plumbing, accessibility and technological requirements. And not every historic house was well oriented or well ventilated.

When I translate these principles into contemporary residential design, I don't copy a historic house. I ask what the house was trying to accomplish.

I want to be clear about something. I am an architect in Barbados. I am not going to pretend every room can stay naturally comfortable through every hour of every season. Bedrooms, certain offices, high-occupancy spaces, humidity-sensitive environments, specific medical and technical applications — mechanical cooling is often the right answer.

• First, stop the sun.
• Then catch the breeze.
• Then move the air.
• Then allow the building to breathe.
• Then use mechanical cooling for whatever the architecture cannot reasonably solve.

That sequence produces a house that feels different — not necessarily colder, but more comfortable. A mechanically cooled house can hold 22°C. A well-designed tropical house may sit warmer than that, but if the space is shaded, ventilated and moving air across your skin, it can feel considerably better than an artificial climate.

The most interesting thing about Barbados' traditional architecture is that its intelligence hides in plain sight.

• A veranda shades the wall and the openings behind it.
• A jalousie gives the occupant adjustable ventilation.
• An overhang protects the wall from direct sun.
• A high gable can provide space for warm air to rise and leave.
• Orientation determines which rooms receive the trade winds and afternoon sun.

I return to old buildings to understand the practical decisions that still work in this climate.

It needs better sequencing of technology and architecture. A solar panel cannot fix a badly oriented house. A large air-conditioning system cannot make poor shading good design. Smart-home controls cannot compensate for excessive solar gain.

Technology can refine performance, but the architecture sets the initial demand. A well-oriented, shaded and ventilated house needs less equipment to remain comfortable.

Before specifying equipment, I record the sun, wind and rain, then trace where shade and airflow can do useful work.

• Where is the sun?
• Where is the wind?
• Where will the rain come from?
• Where can the building be shaded?
• Where can air enter?
• Where can air leave?
• Which spaces genuinely need mechanical cooling?
• And then: what can the architecture solve before the equipment arrives?