Low Cost, High Impact: Why We Painted the West Wall White

Did you know that using air conditioning releases massive amounts of Carbon Dioxide? Since we live in a hot climate going without an a.c. unit is not possible in our current house. We instead strive to use it as little as possible. We opt for ceiling fans in the rooms we’re currently in, wear lightweight clothes, open the windows for natural ventilation on cool nights or breezy days, close the blinds and curtains to block excess heat from entering the house on the solar gain side, use natural lighting, cook outside, and keep the thermostat set around 80 °F. We’ve added to it by changing our west wall.

Even so, there is more we could do. By planting shade trees or green walls we could use a natural living barrier. This change would modify the microclimate around the house. We could use a fountain to passively cool the air via evaporation, or funnel the summer breeze through the open windows to remove heat via convection currents. Also, we could extend the roof of the house with a wraparound porch, paint the house a lighter color, install a geothermal cooling system, re-roof with lighter colored roofing material, or add insulation to the roof. We could even re-site the house to a better solar orientation!

What We Did Instead

A lot of these options are expensive, use more newly purchased materials, require regular maintenance, or will take some time before they can help cool the house. With a tight budget and the need for something rather instantaneous the idea of painting the west wall of the house seemed the most reasonable. It helps that I had recently been “gifted” an almost empty 5-gallon bucket of white exterior paint by someone who knows my desire to re-purpose or upcycle whatever I can.

Scrounging through my tools I came across a 1″ paintbrush and a paint key to open cans. Well, it’s not ideal to paint 320 square feet with a 1″ brush, but I had it and there was no rush. I decided to paint the corners of the house first with the leftover paint. It had very little left and the original house colors incorporate white. This also allowed me to note whether or not I could safely and reasonably reach the total area I was planning on painting with my ladder. 

I could, but I would have to go buy a gallon of paint to finish. A thought occurred to me as I was returning the ladder to the shed. Didn’t we have some older leftover paint from when I helped someone else? Maybe there was some light-colored exterior paint. So I rummaged through the recovered lockers and in the last one was three gallons of paint. One cobalt blue, a dark brown, and an exterior white. I picked up the can of white to read the label. Not only was it full, the can would cover the west wall. Jackpot. 

Why Paint the West Wall with White?

So why white and not a different light color? Well, for several reasons. White reflects up to 70% of the solar radiation that hits it, with the potential to moderate temperatures up to 20°F. Less heat on the wall absorbed means the house doesn’t warm up as much. Coincidentally, the a.c. unit is on that side of the house. It will potentially not have to work as hard if the air around the unit itself is cooler. 

White paint also reflects light as well as heat. This advantage gives better light to plant understory plants for one of my shade trees that hasn’t grown to size yet. It also allows a warmer microclimate for me to overwinter more sensitive plants. Finally, as there is already white in the color scheme of the house, it won’t look out of place once completed.