Why is the Second Floor So Hot?

Many modern Florida homes are built as a single story specifically to help with cooling, but if you live in an older home or if you decide to build a two-level home, you may notice that the second floor can sometimes be warmer than the first floor. In this article are a few reasons why this can happen, as well as a few tips of things that can be done to help mitigate the extra warmth on the second floor.

The main thing to remember about heat is that hot air rises because it is less dense than cooler air—that is, the air molecules are more widely spaced because they have more energy (heat). Denser, cooler air thus sinks, letting the hotter air “float” on it, just the way oil floats on water because it is less dense.

Another contributor to warmer upper stories is the roof: the roof absorbs quite a bit of the sun’s energy, and although the attic and insulation between the roof and the interior ceilings helps to mitigate the heat, it is inevitable that some portion of that heat energy will transfer through into the indoor space. Because the second floor is closer to the roof than the ground floor, it will absorb more of this heat, thus making those floors hotter.

The best way to mitigate these problems is to make sure the outlet vents for cool air in the home are bringing cooled air prominently to the upper floors. This will force the cooled air to circulate more through the upper floors. It might even help to partially close the dampers or vents on the first floor to restrict the airflow in those areas so that even more cool air is directed upstairs. You can even turn the system fan from “auto” to “on” so that the fan runs even when the compressor isn’t on to help better circulate air.

Another very important step is to make sure the attic is appropriately vented and insulated. Venting will help move hot air out of the attic so that it doesn’t transfer as much heat to the indoor spaces below it, and insulating will block that heat transfer. Water or rodents can damage insulation and make it less efficient, so it’s important to maintain the insulation to keep the heat out.

It may also be the case that your air conditioning system is beginning to wear out or needs an upgrade to be more efficient for the space. If you have any maintenance concerns, or questions about making your AC more efficient, or even if you need to re-evaluate the HVAC system in your home, be sure to call All Day Air Cooling and Heating today at (239) 357-0727.