Choosing the best windows for natural ventilation is a significant decision in a tropical home. Windows that encourage the most natural ventilation are among the most important factors when building in the tropics.
Generally, windows are a critical part of any home.
Windows allow natural light and ventilation into your rooms. They protect against rain, insects, and other unwanted guests. In addition, they should offer good security and privacy when required. The style and character of the architecture of a building are heavily influenced by your windows’ style, shape, and size.
They are literally your window to the outside world.
Because of this, they are many things to consider when choosing windows in a tropical climate. These include how much air they allow through their opening and resistance to tropical storms. You should also consider their strength and durability against moisture and salt air since these are standard issues in small tropical islands. Airtightness and thermal insulation are also important where air conditioning is in use.
However, this article focuses on the amount of natural ventilation that windows allow. Natural ventilation is critical for creating an ideal thermal comfort level in your interior spaces. Creating as much air movement as possible inside your home will determine how comfortable you and your family will be.
Allowing as much natural ventilation throughout the day is paramount. This strategy means having windows that will enable the maximum amount of air movement. It should also consider maximising the window’s time to remain fully or partially open in various conditions.
When choosing windows for your project, here are a few things you may want to consider to maximise natural ventilation.
When selecting your windows, consider how much of the actual window opening will allow air through. That is the percentage of your window that permits ventilation when fully opened. It is great to want a big window, but that is not enough. It would help if you also were sure that it has a significant portion in ventilation opening.
For example, a sash window that is fully open will allow less than 50% of its total area. However, a casement window can enable close to 100% of its opening. Hence a sash window with the same overall size as a casement will have a ventilation opening that is only half of the casement.
The more or bigger ventilation openings you have, the more air will enter and pass through your home. Hence, there is the potential for better cross ventilation and creating rooms that are cooler and more comfortable.
It is typical for a shower of rain to sneak up on you in the tropics when you least expect it.
I welcome these showers most of the time as they can bring cool relief to a hot day. But a sudden shower of rain can force you to run through the house closing all windows. This fact is essential for windows on the windward side.
Ideally, it would be great if your windows could remain fully or partially open during light to moderate rainfall. That way, you can maintain natural ventilation throughout your home as much as possible. In addition, you won’t have to worry about closing your windows when it rains. Sheltering your window your windows under a porch, patio or large roof overhang will help.
Awning windows are also good in this situation. These are the type of windows I have in the house where I now live. It takes heavy, wind-driven rain to require closing those windows.
With these two main criteria in mind, how do you determine which windows are best for natural ventilation in your project?
Let us consider some of the most popular window types on the market. Out of these, we may see which ones offer the best natural ventilation for your tropical home.
These windows are some of the most common window types in Barbados and many countries in the Caribbean. They also happen to be the most popular windows in the United States of America. I mention this because products and materials in our markets tend to depend heavily on the USA. This occurs because our regions are close to each other.
Sash and sliding windows do not project beyond the face of the wall like some other window types. Therefore, these are great where you have to use the space outside of the window. Hence, the window will not project out into the space.
They are also low-maintenance and offer good air tightness.
Sash windows come in both single and double-hung options, which means either one or both panels are operable or moveable.
However, they have less than 50% of their window area as an effective ventilation opening in either option. They also do little to prevent rain from entering through their opening.
As I said before, these windows are great at keeping out the rain. However, as a result, they also do not allow a lot of ventilation.
The window panels of awning widows tend not to open very wide. Hence they do not have a lot of potential for air movement.
On breezy days, the wind can sometimes temporarily close the awning windows in my current home rather than flow through the ventilation opening.
This implies that more wind pushes against the outside of the windows than through. Some data suggest that most awning windows permit less than 20% of natural ventilation through their overall window area.
There are many contemporary options for casement windows available today. Casements are great-looking windows that allow a lot of air to pass through.
Though they seem more popular now in contemporary-style homes, casement windows have been around for a while. You can find them in many traditional-style homes as well.
The house I grew up in had casement windows. Their clear wide opening let a lot of air in and through the home. However, my siblings and I had to close them quickly once it began to rain.
The great part of those same casement windows from my childhood home was the glass louvres at the top.
They were small and just above the casement windows at a high level. However, these jalousies allow a lot of natural ventilation. In addition, they were great at letting hot air at the ceiling level out.
Most of them could remain open throughout the day and night. However, we had to close or lower a few of them when the rain came.
You could often find jalousies in traditional Caribbean vernacular architecture, in both windows and doors. They were also popular in other tropical and subtropical regions. However, they are not popular in residential construction today as they are thought to be old fashion and low-end.
Traditionally, they were not usually as airtight as some of the other windows. I find this is an interesting point since having an airtight window in temperate regions is essential. It is crucial to prevent cold air from entering the home or warm air from escaping. However, unless you have air conditioning, I wonder if it is not a good idea to have windows that leak air in hot, humid climates.
This could be particularly useful at night when we close our windows for security reasons. They could offer some relief from the heat indoors.
My current home has some louvres in a couple of locations. Very often, on cooler nights, I can feel slightly cooler air lingering around those windows in an otherwise warm interior.
Unfortunately, a window that has the largest ventilation opening is likely to be the one that will let in the most rain. The wind and rain tend to come from the same direction.
Therefore, the best windows for natural ventilation are perhaps those that offer the best flexibility and control in most conditions.
I believe jalousies offer the best flexibility. They allow air movement through almost 100% of their opening. However, you can partially close them to reduce rain penetration.
Casement windows also allow a large percentage of their area for ventilation but are not as flexible. Rain can still get in through the slightest opening.
Awnings, though great in the rain. They offer better rain protection than louvres. However, they often do not allow enough air movement on those hot days. That is because of the limitations on how wide they can open.
Sash windows do not offer the best natural ventilation or protection against rain penetration. As a result, I often question their popularity in our tropical regions.
After considering all of this, keep in mind that they are a ton of other factors that go into choosing a window for your home.
For example, as much as louvres may be my best window for natural ventilation, traditional ones are sometimes hard to maintain. They have many moving parts, which can often be susceptible to wear and tear. They can also be tedious to clean. I remember, as a child cleaning those same glass louvres at my old home and how much of a pain it was. Not to mention the care you had to take so as not to damage them because of their fragility.
However, they are some companies today that provide much better quality jalousies. They offer better security, airtightness and even resistance to solar heat gain.
In addition, a study was done on window sizes and their performance with natural ventilation. It says that the sizes of windows, along with the angle of the wind, change the air movement inside.
They are other issues like their durability and strength in severe weather events like hurricanes.
These, along with many other issues, you need to consider when choosing a window for your tropical home design.
Ventilation opening is one aspect of a window for tropical architecture. As we consider other issues concerning windows, we will discover what the best windows for various conditions in your home project are.
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