Let Cool Air Flow In

Written by Virginia DeVit on Wednesday, 18 July 2012. Posted in HVAC Pointers

AC Season - Ventilation

Nights are cooler than the daytime, except for the rare occasion. Even in the summer, the outdoor air can reach your desired cooling temperature. So take advantage of the cooler times and help the energy efficiency of your home. So let the cool air flow into your home and create a ventilated space. 


Ventilation includes both the exchange of air to the outside as well as circulation of air within the building.  There are two types of ventilation; passive ventilation uses natural airflow and active ventilation uses a mechanical device to aid the process.  Exchanging air is one of the most important factors for healthy indoor air quality; it removes unpleasant smells, removes excessive moisture, prevents stagnate interior air and for the purpose of this article, it can help cool your home.  

The passive methods are so simple they hardly bear mentioning.  Open your windows and generate a cross breeze through your home on the cool days, evenings and nights.  Cross breezes have two functions; pulling cool fresh air indoors and forcing the warm stale air outdoors.  There are a few simple steps to create the desired cross breeze through the home.  Open windows that are across from each other; wide open on one side and cracked open on the other side of the home.  Open the interior doors to create clear uninterrupted pathways through your home.   

Active ventilation is best used for when the air is too still and the cool air just will not enter your home easily.  By placing a fan near an open window, you can easily create the desired cross breeze.  This is the simplest method of active ventilation, since it does not require a difficult installation and is very portable.  All it requires is a fan near an open window and pushing air to the outside.   It may sound weird, but removing the stale hot air from your home creates a vacuum that will pull fresh cool air in from another window. 

Running ceiling fans will also aid in circulating the air through your home.  In summer, the fan's direction of rotation should be set so that air is blown downward (appears counter-clockwise from below).  The blades should lead with the upturned side as they spin.  The breeze created by a ceiling fan speeds the evaporation of perspiration on human skin, which makes the body's natural cooling ability more efficient.  Moving air around makes the air slightly warmer, so it is a waste of electricity to leave a ceiling fan on when no one is in a room.  

In rooms with ceiling heights two stories or higher, ceiling fans work differently.   These ceiling fans are too far away from the people in the room to have the cooling effect on the skin.  In that case the fans should pull the cool air upward (appears clockwise from below) to create an even temperature throughout the room.  Opening a window upstairs will also help the cool airs upward flow and the warm stale air’s exodus from your home.

During these hot summer months, consider turning the fan in your air conditioning system to the ALWAYS ON setting.  It creates the pleasurable cool feeling on your skins so you can raise your thermostat a few degrees.  Relying on your air conditioner’s fan, allows your windows to remain closed on the hot days and still remain cool inside.  This method has one downside; fresh air is not introduced to your home resulting in no improvement on the air quality.  

This problem can be remedied by adding an ERV (energy recovery ventilator) to your air conditioning system.   All it takes is forgetting to close one window on one hot, humid day and all of your energy efficient hard work flies out the window.  An ERV is an air-to-air heat exchanger that transfers heat and moisture.  Throughout the cooling season, the system works to cool and dehumidify the incoming, outside air.  So, you can have your cake (fresh air) and eat it too (no humidity and no heat).  

These are just a few simple ideas to create a cooler home.  Installing air conditioning systems will always be best for this task, but that does not mean that we can’t do our small part to helping its efficiency.  So take a look around your home and see if these small tricks can help you; open a window, turn on a fan or use an ERV.

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