Whole-House-Fans Reduce Energy Use

Recently we made a MAJOR improvement in our home energy efficiency, especially in the hot summer months.   We have cooled our home by cooling our concrete radiant floors for the past couple summer seasons.  This has worked out fairly well, though it is hard to closely regulate the house temperature.  The heat pump uses a fair amount of electricity from our solar panels thanks to short run times.  This information is provided for my introduction to the need for whole house fans.

We should be building up energy credits in our grid account during the summer.  However, the credits have fallen off compared to previous years when we were not cooling the floors. Our Heat Pump  and well pump require about 3500 watts for heating or cooling.  That figure includes the smaller power drain for the smaller well pump (about 900 watts).    Let’s assume that the heat pump only comes on for about five hours per day in the summer.  That energy is equivalent to 3500 watts times 5 hours or 17.5 kWh per day!  But it takes that amount of energy to maintain a comfortable temperatures most of the summer.    We still use 1,000 kWh more summer energy than without using a heat pump for cooling.  Using whole house fans this summer should reduce heat pump running time significantly.

Gary, the owner of the builditsolar web site was the first to acquaint me with whole house fans.

I remember reading about whole house fans in my friend Gary’s www.builditsolar.com web site a few years back.  Gary was very high on the effectiveness of his whole house fans.  Also he only lives a short distance from us so the weather is similar.  Gary had placed a large fan above an opened access to blow hot air from his house into the attic.  He opened screened windows in his home to replace hot house air  with cool evening air. His house maintained a cool temperature throughout the day by closing windows in the morning.  I took Gary’s advice and purchased some whole house fans from AirScape Fans in Oregon.

Using whole house fans, here are the basics of our new cooling plan:

  • One of the whole house fans is now installed at the highest point of our shop ceiling.  That fan sucks air from the shop below into the attic space.  There it can easily escape through the ridge and soffit vents.
  • Cool outside air replaces the hot shop air when we open a shop window to the outside.  The whole house fans can very efficiently maintain 60 to 70 F  summer temperatures in the shop.
  • We placed another fan in the East end of the house between the laundry room and shop. I can turn on this fan to pull hot house air from the house and exhaust it into the shop.
  • The larger of the whole house fans exhausts the surplus house heat on summer mornings into the attic.
  • This whole house exhaust fan also helps cool the house by heating the shop in the winter.

We chose whole house fans mostly for efficiency, but also for faster temperature regulation.

Our two whole house fans are both very energy efficient.  They have an R49 value between the two sides of the walls.  That insulation stops  heat loss or gain when the fans are not in operation.  Both fans utilize very little electricity compared to the heat pump.  That goes for either heating or cooling.  Remember that we are only transferring cool or hot air from one space to another.  The whole house fans do not take a lot of energy doing that either. Compare that to running a compressor pump and well pump.  They transfer heat from well water to radiant floors but they take a lot more energy doing it.   Still, the heat pump and well are three times as efficient as an electric boiler!

Our house exhaust fan dumps hot afternoon passive solar heat into the shop which is thereby warmed.  That will probably happen only in the late fall, winter and early spring months.   Our our low E windows produce a lot more heat in the winter than in the summer!  It has allowed us to cool the house when otherwise the temperatures can rise to as much as 85F.  On exceptionally clear sunny days we sometimes have to open outside windows.  The heat dumping routine from the house saves energy.  We do not even turn on the heat pump except during rare cold snaps anymore.  That is especially so if we maintain a temperature of only 50 to 60F which is a pleasant for working.

Credits

I thank AirScape Fans for helping me select the best possible solution for my cooling challenges.  I purchased their latest 5.0eXR 5000 cfm Whole House Fan for our shop attic.  The 1000 cfm  1.0XR Whole House Fan is used as our house exhaust fan between the house and shop.  I selected these AirScape whole house fans for the following reasons:

  • They offer what I believe is the very best operating efficiency in the industry.  That is mostly due to advanced motor and air flow technology:
    • My 5.0eXR 5000 cfm model offers seven power ranges.  They range from only 28 watts (at 1300 cfm) to 800 watts (at 5064 cfm)
    • The 1.0XR 1000 cfm model offers two power ranges: 40 watts (at 600 cfm) and 80 watts (at 1000 cfm)
  • Extraordinarily low acoustic noise (sound) levels (especially in the slower speeds) satisfies even my wife:
    • The highest 5000 cfm sound level compares to other fans we own that are only a few hundred cfm!!!!  The actual measured specs for this fan range from on 39 dBA lowest to 65 dBA in the highest speed
    • The 1.0XR fan sounds very quiet in the low speed mode and quiet enough in the high speed mode.  The actual specifications show a 43 dBA in low speed and 53 dBA in high speed
  • The air plenum rubber gasket seal and insulation reduces heat losses significantly when the fans are off.  AirScape Fans employ the latest in vacuum insulating technology as used in the most advanced refrigerators and freezers

Installation of the largest of our whole house fans:

My physical condition has waned over the years.  Yet I was able to install the larger 5.0eXR Whole House Fan into our shop attic all by myself. It amazed me that I was able to maneuver the unit into some pretty tight attic spaces. Actually I think that unless you are in good physical condition and health, hire a professional for this job.  The job will take a professional far less time than it took me.   If you do it, just take it very slowly and very carefully!  My only problem is that I was left with some sore muscles I hadn’t used for decades.  It took so much longer to heal than it used to.  At least now I feel in far better shape physically than before.

I used our motor coach as the perfect work platform.  That is because our shop ceiling is 16 feet off the concrete floor.  Note the attic entry hatch to the right of the Whole House Fan intake grill.  I accessed the attic by removing the foam insulated hatch cover.  The Whole-House-Fan was installed over the intake grill four feet away from the hatch.  A low ladder was used to work on the cutaway for the grill and to get into the access hatch.

A whole house fans work platform was provided by our travel coach.

The ladder and coach allowed easy access to one of the whole house fans (in the attic).