Condensation on a window is usually one of the first signs that the humidity within the space is too high.Buildings can get sick too. If you’ve ever been concerned with the number of staff that are always sick or suffer from allergies, this is a classic case of sick building syndrome or SBS for short. When it comes to the indoor air quality of buildings, there are four main areas of focus for SBS — temperature, volatile organic compounds (VOC) and particulates, humidity, and air exchange. Humidity is the focus of this article.
The humidity spectrum isn’t so different than the children’s story “The Three Little Bears” with the adage of too little, too much, and just right. The effect of humidity levels can be separated into three parts — symptoms, health effects, and comfort.
Ideal humidity levels
According to the Mayo Clinic, the ideal healthy humidity levels are between 30 and 50 per cent. This translates into 30 to 50 per cent of the maximum amount of water the air can hold at any given temperature. Remember temperature was part one of SBS; so, how does humidity affect temperature? It affects the way our bodies react to temperature.
Most of our bodies’ comfort zone is 70F and 45 per cent relative humidity (RH). Temperature and humidity can play tricks on our body’s comfort zone. As an example, if you raise humidity levels, our bodies will find comfort at lower temperatures and vice versa. If we lower humidity levels, we will need to raise the temperature to find that comfort zone. This being true, we can save energy by adding moisture to the air and lowering heating requirements in the winter. Conversely, if we reduce humidity levels in the air, we will find comfort in higher temperatures, thus reducing the load on the air conditioning system.
Other moisture-producing additionsto a building could
be living walls, which have been growing in popularity. This living wall is located at the Cambridge City Hall
in Ont.
Humidity too high
The first symptom of too much humidity will be dampness, wet or foggy windows, musty odours, and stuffiness. The health effect comes from the bacteria and viruses that thrive in humidity levels higher than 60 per cent.
Here lies the answer as to why staff are always sick with colds or flu in the workplace.
Those little microorganisms grab hold of the water droplets in the air and transport themselves through an entire room or building. They could travel upwards of 30-ft. before dropping to the floor out of our inhalation pathway. People with any respiratory issues will be the first to fall sick in high humidity levels.
Dust mites thrive on RH above 50 per cent; they are everywhere, especially in dark damp places. This can be a trigger to allergies in the winter. Temperature and comfort cannot happen with excessive humidity as well. You may notice people in the office constantly adjusting the thermostat or questioning if it is working. This is a classic case of too much relative humidity.
RH is too low
When humidity levels drop below 30 per cent, a new set of problems arise, and we call it the “ahem” syndrome. This is when everyone in the office is walking around with a sore throat from making an “ahem” sound. Static electricity is a sure sign. Dry air will reduce mucus production and create dry nasal passages, this makes us vulnerable to other respiratory issues.
Other side effects of dry air within a building can showcase itself as desks and cabinets cracking, or with premature carpet or flooring wear. Can’t forget about those dead dust mites and fecal matter still floating around in the air, either!
This can affect our body’s comfort zones too. Dry air is cooler to the touch, which leads to occupants being cold even at higher-than-normal thermostat settings; not to mention the office wars created by people not able to control the room to reach their body’s comfort.
Making sure humidity levels are just right is key to ensure the building doesn’t become “sick.”Just right
The perfect temperature created and maintained by the sweet spot of humidity, as previously mentioned, is 30 to 50 per cent or better yet 40 per cent RH. Within this range, the only sound around the office will be of people speaking, little to no coughing or nose blowing, and no one has touched the thermostat all day. The pesky cold and flu season is well under control at this point.
Tough truth
If only every building resided within the sweet spot, but we know they do not, of course. It is our profession that has the power to diagnose the levels of relative humidity and prescribe the remedy. Sometimes it requires a simple solution, while other times it is like a complex surgery. So, Dr. IAQ, we have diagnosed a building with SBS.
If we follow these simple steps, we can provide a solution — identify the source, eliminate other possibilities, and deduct what can be provided to eliminate the issue. With ageing buildings, the source may be an increase in capacity or additional moisture. Breathing alone will increase carbon dioxide. There are other moisture-producing situations than increased foot traffic alone, like excessive plants (the addition of live walls), showers, or production processes.
Dust mites thrive in environments where the relative humidity reaches 50 per cent and are a common instigator for allergies in the wintertime.The ageing HVAC system has probably lost some of its conditioning abilities, although air conditioning is not a dehumidifier. In cases like these, complete upgrades may be necessary. For older buildings, ventilation may need to be added, or possibly commercial-grade HRVs. Whole building dehumidifiers can be a remarkably effective add-on solution, although stand-alone they may not keep up. But added to the HVAC system, it may just do the trick!
There are many ventilation courses available today that cover the four categories of indoor air improvement: temperature, VOC and particulates, humidity, and air exchange. I encourage you to seek out the best one for your needs.