Over the past few blog posts we have been
looking at code compliance and the difference between meeting the code
and exceeding the code. In this post we
are going to look at the ASHRAE 62.2 ventilation standard. In past blog
posts we have described aspects of the standard such as local ventilation and continuous ventilation. In short ASHRAE 62.2 is a national ventilation code to promote air exchanges in your
home to better the indoor air quality (IAQ). The basics of the code are
to have an exhaust fan running continuously at a low speed, then using
other fans throughout the house to take care of higher ventilation needs
like cooking
or when the shower is in use. Meeting the code means that you have an
exhaust fan installed in a centrally located area of your home.
Great,
that sounds fairly easy and for the most part it is. A popular way to
solve for this is to install a two-speed exhaust fan in the bathroom.
This
is a fan that runs constantly on low speed at an almost silent sound
level then when more ventilation is needed boosts to high speed. This
can be done by a switch, humidity sensor, or motion sensor that is
integrated into the fan.
So far so good; I think we have it covered. Code met, let’s move on to the next item. Here’s the thing (okay, you didn’t really think we would end it there did you?), while to the letter of the code, this installation might meet it, we need to look at it a little closer. First we need to think a little about how air travels and where contaminates are located in the home. Generally, the kitchen cooking area is going to be the location of the largest amount of contaminants generated in the home. If you are installing the continuous running exhaust fan in a bathroom, it is generally going to be on the other side of the home as the kitchen. This means that the exhaust is going to be pulling air from the kitchen throughout the home and through the living spaces. Not exactly an ideal
solution. Here is another issue. What happens when the bathroom door is closed? Now you have either cut off or severely restricted the airflow. Let’s take it one step further. If the fan is installed in a master bathroom, that typically means two closed doors to navigate through.
Some installers will place the fan in the living room or a hallway. This is better as you won’t have to deal with the closed-door issue as much, but you are still drawing air that you want to exhaust through living areas. So I
guess we are doomed. Can’t install it in the bathroom, can’t install it in a living area, where then?
There is a solution that takes all these issues into account. Place the continuous ventilation in the kitchen. There are reasons the kitchen is called the heart of the home. Typically the kitchen will be in a central location of the home or at least open to the rest of the home. This makes it a
perfect location. There are now range hoods available that have multiple speeds. They have a continuous operation speed that will solve for, as the name states – continuous airflow. The sound level at this speed is barely detectable. When the cooktop is being used, they have higher speeds to take care of the additional airflow needed to properly ventilate while cooking. Now you have the ventilation placed at the source of one of the largest contaminators of the home. The added benefit is that the continuous speed will take care of the residual contaminants in the air after the cooking is done. While we would like to think everyone is properly using their range hood, we also know that is not always the case. These range hoods install the same as traditional range hoods, so if you are installing one anyway, why not solve two things at once. The only consideration is that they are going to cost more than an entry-level basic range hood. The counter to that is if you go the bathroom route, a two-speed exhaust fan is also going to cost more than a standard exhaust fan also. Another point is that you will also have a much quieter operating range hood.
