CleanTechnica is the #1 cleantech-focused
website
 in the world.


Energy Efficiency The cool kids on the block: Ceiling and whole house fans for conservation

Published on July 25th, 2013 | by Dan Thiede, CERTs

6

Pairing Ceiling Fan And Air Conditioning Works Wonders In The Heat

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

July 25th, 2013 by
 

This post was originally published on CleanEnergyResourceTeams.org

On those summer days that are particularly hot and sticky, the use of a ceiling fan in conjunction with air conditioning or natural ventilation may be your best choice to cool things down. The wind chill effect that increased air movement creates on skin means that turning on a ceiling fan will allow you to raise your home thermostat setting about 4 degrees with no reduction in comfort. From a conservation standpoint, it is important to keep in mind that fans should be turned off as you leave the room—fans cool people (through the wind chill effect), not rooms.

Ceiling and whole house fans for conservation

The wind chill effect that increased air movement creates on skin means that turning on a ceiling fan will allow you to raise your home thermostat setting about 4 degrees with no reduction in comfort.

The US Department of Energy recommends that ceiling fans should not be used in rooms any shorter than eight feet high. Also, blades should never come closer than 8 inches from the ceiling and 18 inches from the nearest wall. Ceiling fans are a great choice for the summer months, but will likely not reduce your heating costs in the winter. The extra movement of air will also cause a wind chill effect in the winter and may prompt homeowners to unnecessarily raise their thermostat temperatures during those cold months.

How a whole house fan operates.

In addition to getting a cooling effect from ceiling fans, you can achieve considerable home cooling through the use of a whole-house fan. A whole-house fan is installed in the ceiling between a living space and attic. With windows and doors open, it pulls air through a living space and pushes it into the attic space, then forcing the air through the gable and/or soffit vents. As long as the air outside is cooler than indoors (most common in the cool evenings and early mornings of summer), then the fan provides actual cooling.

In technical terms, a whole-house fan is capable of moving air at a flow rate of 4,500 to 7,500 cubic feet per minute. If a home has 1,500 square feet of living space, then the air can be completely refreshed every 2 to 3 minutes with a whole-house fan. It would be great if that meant our homes would cool this quickly, but unfortunately all the objects in our homes and the homes themselves hold heat and so a whole house fan must run for a couple of hours to cool a home down to the outdoor temperature.

In comparison, box fans are portable appliances which can provide cooling effect or air flow depending on its use. If a box fan is simply set-up in a room and directed toward people, then it will provide the cooling effect similar to a ceiling fan. Alternatively, a box fan could be set-up in a window to direct air outward while other windows and doors are open in the house. In this configuration, it will provide air flow through the house and act more like a whole house fan. However, box fans typically have flow rates of 2,000 to 2,500 cubic feet per minute and will take more time to cool down an entire home in comparison to a whole-house fan.

There are also adjustable fan systems specifically designed to fit in windows, but the flow rates offered by these systems range from 250 to 1,500 cubic feet per minute. It is best to set-up fans in windows located on the side of the home that is calm (not receiving the full force of the wind) and shaded, if possible. Multiple window fan systems may be needed to get the desired air flow and cooling.

Cooling Option Energy Use
Central Air Conditioner 2,500-3,500 watts
Window Air Conditioning Unit 500-1,500 watts
Whole-House Fans 200-350 watts
Box Fans +/- 100 watts
Window Fans +/- 70 watts
Ceiling Fans 25-90 watts

 

Other home cooling tips include:

  • Before leaving your home, close all blinds to block out sun during the day and make sure windows are shut tight to keep all excess heat out.
  • Use clothes lines to dry laundry instead of creating extra heat in your home with the dryer.
  • Keep your kitchen cool by having a cookout or grilling meals outdoors.
  • There should be no need to use a dehumidifier at the same time the air conditioner is running. Air conditioners provide dehumidification and a dehumidifier generates heat, forcing the air conditioner to work harder.
  • On that last note, do activities that will increase humidity like showering and washing dishes later in the day when it has cooled off outside
  • Replace incandescent light bulbs which emit heat with fluorescents. Check out the Right Light Guide for more lighting information.
  • Turn a fan into a homemade AC unit. Place a bowl of ice or frozen water jug in front of the fan so that it blows cool air.
  • Consider doing some outdoor landscaping to help keep your whole house cool. See great landscaping tips here.

Click here to view additional fan information on the US Department of Energy’s website >>

Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.

Print Friendly

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

Tags: , , , , , , , , , , , , , , ,


About the Author

is the Communications Coordinator for the Clean Energy Resource Teams, or CERTs, at the University of Minnesota. CERTs works to advance the adoption of renewable energy and energy efficiency projects in communities across Minnesota by helping people learn, connect, and act.



  • Kenneth Lawrence
  • Amy H. Gidley

    There are plenty of ways we can keep ourselves and the house cool. Cooling systems have been discussed in this post that will help us keep cool. These cooling systems here definitely work and it is all up to us which to choose. We should choose one that would best work for our family and needs.

    AtticFan.com

  • http://www.facebook.com/lisa.benson.37051 Lisa Benson

    Quiet Cool Whole House fans are super efficient and quiet compared to traditional whole house fans. Quietcoolfan.net sells them and they will ship all over U.S.

  • Wayne Williamson

    1. done…the house is a dungeon…
    2. the dryer is in the garage.
    3. in Florida, and this year as well as the past few, its raining all the time.
    4. never had one here, its way to hot and humid.
    5. 3 am in the morning is not when i want to be taking a shower.
    6. probably 98 percent complete, very few incandescent lights
    7. last thing I want is some more humidity
    8. shading is great except when the 10 ton branches fall on your house.

    Just some tongue in cheek for those that enjoy that…probably works well in Minnesota.

    Best thing for me has been to replace the 25 year old air conditioner, replace the leaking duct work, blow a ton(tech term) of insulation in the attic, replace the 20 year old refrigerators, replace the 25 year old hot water heater, and get some really efficient washers and dryers. Saves around 150 a month in electric bills.
    Still need to replace the single pane windows;-)

    • Wayne Williamson

      I should have added, since its the title, there is a ceiling fan in every room…

      • Tom G.

        Hey Wayne:

        You are well on your way to an energy efficient home with everything you have done. But before summer comes I would get those windows replaced as you suggested. You will not believe how much difference Low E dual pane windows will make.

        I could literally feel the heat coming thru my old single pane windows here in Arizona. After the windows were installed it was so noticeable I couldn’t believe the difference. Some articles say that 30% of all heating and cooling is lost thru inefficient windows and I believe it.

        New dual pane Low E windows should easily knock another $20-$40/mo. off your electric bill.

        Enjoy

Back to Top ↑