Living in Bryan and College Station’s hot, humid climate brings unique design and construction challenges. One such challenge is the traditional use of thermal mass walls, which, while beautiful, don’t work as well in our local environment. However, with a few adjustments, we can still take advantage of this design approach.
What is Thermal Mass?
Thermal mass refers to thick, dense materials like stone, adobe, or brick. These materials absorb heat during the day and, in cooler climates, release it at night when the temperature drops, resetting the cycle. In hot, dry regions, this works well because nighttime temperatures dip enough to pull the heat out of the walls.
However, our high humidity prevents nighttime cooling from being effective. Instead of releasing heat, thermal mass walls in our climate can trap it, causing buildings to get warmer over time—a problem if you’re trying to keep your home cool.
Brick: A Common Misstep
Despite this, brick remains a popular veneer choice along the Gulf Coast. Even when it’s not a structural component, the brick acts as a heat magnet, collecting solar energy and warming the surface next to your home.
For example, my 1950s home originally had a full brick veneer, which significantly contributed to heating the interior. I removed the brick, added a second insulated wall, and replaced the exterior with fiber cement siding. This allowed me to double the insulation, improve the air seal, and reduce the exterior heat. Plus, I think it improved the overall look of the house.
Using Thermal Mass Effectively
So, if thermal mass doesn’t work well outdoors in a humid climate, how can we still use it to our advantage? The solution is to bring the thermal mass indoors, away from the heat source. Indoors, the material stabilizes at the ambient room temperature, helping regulate indoor conditions as outside temperatures rise. The thermal mass absorbs some of the heat, reducing the load on your cooling system.
This can lead to a more efficient air conditioning system because there’s less of a peak cooling load during the hottest part of the day. In theory, this allows for smaller HVAC systems and a more energy-efficient home.
Challenges and Opportunities for Research
Unfortunately, there’s still much research needed to quantify these benefits. Current HVAC sizing programs don’t account for the impact of indoor thermal mass, and air conditioning companies are cautious about deviating from standard sizing formulas. At Stearns Design Build, we work closely with our trusted HVAC mechanic, frequently encouraging smaller system sizes because our designs aim to reduce cooling loads—even when these reductions aren’t factored into traditional calculations.
By designing thoughtfully and incorporating innovative solutions like indoor thermal mass, we can create homes that perform better in our hot and humid environment, keeping you comfortable while reducing energy consumption. Read our next blog post, where we explore indoor thermal mass.
