How to Improve Thermal Comfort with Skylights

Did you know that Americans, on average, spend 90% of their time indoors? And many of us have spent more than that at home over the past year. That's why, in normal and not-so-normal times, it's important that our homes meet our thermal comfort needs. But how do you plan for that when thermal comfort can vary so drastically from person to person? Scientists think the key is in air movement and natural ventilation.

In other words, skylights may be just what your home designs need to improve thermal comfort for your future homeowners.

Thermal Comfort Parameters

Before we can understand how skylights improve thermal comfort, we must first talk about the parameters that go into thermal comfort. According to the Fanger Model, developed in 1970, there are six parameters that affect our thermal comfort in a home:

• Metabolism
• Clothing insulation
• Air temperature
• Air motion
• Mean radiant temperature
• Relative humidity

Psychological parameters, such as individual expectations, also affect thermal comfort. The Fanger Model assesses thermal comfort in given spaces based on temperature and occupancy satisfaction, and it has found these parameters to affect thermal comfort the most. And with the exception of clothing and metabolism, skylights can help influence all of them.

How Skylights Improve Thermal Comfort

Let's tackle those four parameters of thermal comfort one by one to see how skylights influence and improve them.

1. Air temperature: Venting skylights can be used to naturally adjust the temperature of an interior space. They open slightly, creating a breeze that releases warmer air and humidity.
2. Air motion: Venting skylights, when opened with vertical windows, can mobilize air all throughout a home through a phenomenon known as the Stack Effect, which we'll talk about more below.
3. Mean radiant temperature: Skylight accessories, like shades and the Smart Home compatible VELUX ACTIVE with NETATMO, can help contribute to temperature consistency in the home.
4. Relative humidity: When venting skylights open, they allow accumulated humidity to escape, which can help prevent too much moisture in the home's air that could lead to mold or mildew.

Utilizing the Stack Effect

As we mentioned above, the Stack Effect occurs when skylights and vertical windows are opened at the same time. Through the open skylights, warmer, stale air that's become trapped in the roof or ceiling can escape. While this is happening, cooler fresh air comes in through the vertical windows. This creates a cooling effect that can work throughout the whole home if skylights and vertical windows are strategically placed.

Learn more about how skylights and the Stack Effect contribute to thermal comfort in the This Old House 2021 Modern Barnhouse in the video below: