Although it may feel like it's hard to believe, people have survived the unbearable heat of the summer for millennia without air conditioning, largely due to carefully-considered design choices they made in their homes. In fact, there are plenty of passive and sustainable design solutions—both large and small—that can be employed to reduce heat gain and the need to artificially cool a space with air conditioning. Read on to learn about five major strategies you can try out for yourself in your home.
1) Close Your Blinds
While it's rare to hear a design professional recommend keeping natural light out, in the summer, a lot of heat gain in interior spaces occurs because of the amount of sunlight that passes through transparent materials, including glass. Unless you've replaced the glazing in your windows with a lower solar heat gain coefficient (SHGC) or have newer windows where SHGC was a consideration, you should try to reduce the amount of light that reaches inside, especially during peak hours between 11 a.m. and 3 p.m.
The best way to reduce heat gain is to stop the sunlight from the outside with exterior shutters, louvers, or rolling blinds. If you don’t have those, interior shutters, blinds, or curtains are great options. Even slightly sheer curtains can reduce the amount of sunlight enough for you to feel a difference.
2) Open Your Operable Windows
Many homes, especially those constructed before World War II and the advent of air conditioning, were designed for natural ventilation with operable windows. By opening windows on opposite sides of a home, you can create cross-ventilation for a consistent natural breeze.
This is especially true for transom windows, which are located above doorways or are placed higher up on an exterior wall. This is because these windows circulate the hot air that rises, making room for more hot air to rise, and therefore bringing in cooler air that's lower to the ground. This cycle, called the stack or chimney effect, is one of the most effective naturally-occurring cooling methods out there.
3) Create a House-Wide Stack Effect
While operable transom windows can take advantage of the stack effect in smaller areas, you can recreate the same effect throughout an entire home on a larger scale. If you live in a multi-story home, you can use an existing stairwell or other vertically-oriented space to allow for air to move from high to low, opening windows in the upper floors so that you can release the hot air that's risen.
To ramp things up even more, you can install a window fan in one area to increase air flow. To ensure efficiency, you should try and make sure that you have roughly the same square footage of openings for incoming and outgoing air—i.e. the air will circulate out better if you have, say, three large windows open downstairs and three large windows open upstairs, as opposed to three large windows downstairs and only one small window open upstairs.
4) Install a Water Feature
If you live in a hot, arid climate or a region that experiences hot, dry summers, installing a water feature in a garden or courtyard is a helpful way to cool the air directly around a home. As the water evaporates, it cools the air, creating a microclimate. However, for this to work, the water feature should be "active," ensuring that as much water and air are in contact with each other as possible.
For example, a misting system or circulating water fountain provide better cooling than a reflecting pond. Water features have acoustical benefits as well. A bubbling fountain or gurgling stream can be soothing and calming, and can also mitigate unwanted noise. While some critics are concerned about the conservation of water, it's possible to use gray water (non-potable, but still relatively clean waste water that has been recycled from baths, sinks, washing machines, and other kitchen appliances) in fountains to avoid unnecessary waste.
5) Plant Greenery in Key Areas
Another passive approach that can be used to cool a home is to plant vegetation in locations that either provide shade in strategic areas or guide prevailing winds into a home. Like outdoor shutters or blinds, thoughtfully-sited trees and shrubbery can shade windows to prevent direct sunlight from entering an interior space.
In regions that experience cold winters but hot summers, deciduous trees like elms and maples can provide shade in the summer while allowing sunlight to heat a space in the winter. However, it’s important to pay attention to the location of the plant. A tree located on the east side of a house doesn’t help nearly as much as a tree on the west side. You’ll also want to try and make sure that you maintain a path for prevailing winds to naturally enter the home.