Our Friend and Our Enemy
First of all, what is humidity?
Humidity is a measure of the amount of water vapor in the air. Relative humidity measures the amount of water in the air in relation to the maximum amount of water vapor (moisture). The higher the temperature, the more water vapor the air can hold. Relative humidity is what your morning weather reporter would refer to.
Humidity is a natural part of our atmosphere, it comes from the amount of water vapor in the air. Water vapor enters the atmosphere by evaporating from the large bodies of water on the Earth’s surface including lakes, oceans, and seas.
How temperature affects indoor humidity levels
Colder air cannot handle as much moisture as warmer air. Temperature in relation to humidity is important, especially as we spend 90% of our time indoors. Consider for example a winters day. The outdoor air could have a 100% relative humidity at 5°, and therefore contain 0.2 grams of water. Indoors however, 5° would be very uncomfortable, so we would warm it up. When the outdoor air is heated up to 23° indoors, the absolute amount of water in the air is still the same. But since warmer air can hold more water, the relative humidity goes down to 33%.
On the other hand, warm air can handle more moisture than cooler air. For example, a warm and humid summer with 80% humidity at 30°, would mean that the outdoor air contained 0.8oz/m3 of water. In our homes, 30° feels very uncomfortable so many would use air conditioners or fans to cool it down again. A fan in humid weather works well as it harnesses the moisture in the air and cools our bodies quicker than if the humidity was low. If you cool it down to below 26°, the relative humidity level goes to 100% and the water condenses (The dew point). That is why air conditioning systems often have a dehumidifier built-in. Without them, your walls in the home would be soaking wet during the summer.
In subtropical climates our summers are hot and steamy. We have an abundance of humidity, combined with high temperatures creating a stifling atmosphere when there is no breeze. Large industrial buildings and buildings that are not well ventilated suffer the effects of this the most. If there is no air movement the building heats up in the day making it even hotter inside and the humidity makes the air feel heavy. Add an extraction fan in the mix and now it is pulling the heat out of the building and fresh air in from outside. With the moisture in the air from high humidity levels it creates a cooling effect as the breeze passes over our bodies.
Humidity is a natural wonder in our atmosphere that most of the time is our friend. As long as we have a source of air circulation and ventilation there’s no need to be throwing strong words around like enemy. We can help you there.