If you don’t use a room, shut the door and avoid the costs of heating or cooling that room. That’s what search results often recommend if you go hunting for ways to reduce your energy bills.

But what most people don’t know is that closing that door can do a whole lot more: it can make your sick, reduce your comfort, and even raise your energy bills.

When your home was designed, the heating, air conditioning, and ventilation system were installed to provide maximum efficiency throughout your home. A typical furnace or air conditioner can push as much as 40,000 pounds of air through your home every single day. And when you close off a room in attempt to save, you’re actually stopping the system from working the way it was designed.The Problem With Closing Your Door To Control Heating and Ventilation

In theory, the idea makes sense. If you have a 2,000 square foot home and you shut off unoccupied rooms, you’ll be reducing the square footage of your home by several hundred feet. This can reduce the amount of space to condition the air down to 1,500 square feet or less.

In truth, closed doors obstruct airflow. When an interior door is closed, the room is placed under pressure because the airflow the way it was designed is blocked. Air is trapped in the pressurized room, but it won’t stay trapped for long. It will always find ways to escape: under the door, through cracks and leaks, around windows.

And as air is lost, it looks for ways to replace it. And if it isn’t a part of the normal operating system, the draw of air drawn can increase significantly. This replacement air can come from places like chimneys or the furnace flue, and creates a steady draft throughout your home.

That also means the air circulating throughout your home isn’t filtered. It can contain anything from dirt and dust, to humidity and carbon dioxide. And it can do everything from make you sick, to increase mold growth, or even create deadly situations.

There are several options available to solve this problem. The most obvious is to leave all doors open. But for bedrooms, that’s not always an option.

For some, installing a cold air return in every room is an option. But it’s not always a cost-effective one because holes must be cut and ducts run in every room.

You can also put in a transfer grill, which allows air to flow between hallways and bedrooms. They can be placed into a door, above a door, or beside a door. If you choose a transfer grill, it’s a good idea to hire a qualified HVAC contractor so it will circulate air as efficiently as possible.

In addition, an HVAC contractor can perform a whole house audit and show you the most effective things you can do to create efficiencies throughout your home.