efficiency

4.4e WHF ships

We’re happy to announce that the 4.4e WHF is currently in stock and we’re moving product out the door.

What makes this an “e” ?  The motor is an ECM (electronically commutated motor) which when matched up with the efficient blade design gives a great power profile and low noise.

See the details here: http://airscapefans.com/products/Shop/Natural-Cooling/Whole-House-Fans/AirScape-4.4e-WHF

The following graph shows the energy use profile of the 4.4e as compared to the theoretical efficiency of a fan system.

Railways should be open sourced.

Even though railroads are much more energy efficient and deliver lower transportation costs without federal subsidies, why are trucks the preferred mode of transportation?

I think that the answer lies in the fact that the highway truck combination is effectively open source.  The term open source is commonly used in the software world, but it applies here as well.

The platform is a highway, which just about anybody can use, provided they obey rules for weight, size, and safety of their modules (trucks in this case). This gives a tremendous amount of freedom to truckers and shippers to control their own destiny.  Ask anybody who has used the railroads for shipping and you will see that a rigid central planning department controls how and when your freight arrives.

How about this for an idea. Let’s make the railroads into a regulated monopoly. (It works for electricity, water, and gas BTW). The railroad makes its income by maintaining the infrastructure.

Heat Flow

We get a lot of questions about the ‘R value’ of our damper doors, so we felt that it’s worth going over the basics.

The so called ‘R value’ is denominated in  the units of (square-feet x degree x hour/ BTU). Sounds complicated, but all you really need to know is:

Heat Flow  Q (in BTU per hour) = Area x (temperature differential) / R-value

[For you techies, this formula is valid for steady state, and assumes an infinite plane area.]

Let’s do the math for our whole house fan dampers.  We’ll assume VERY cold conditions in the attic (0° F) and 70° F inside.

Model length width Area (sq. feet) R value Q (BTUH)
1.0WHF 22.5 14.5 2.27 14 11.33
1.7WHF 22.5 14.5 2.27 7 22.66
2.5, 2.5eWHF 22.5 14.5 2.27 10 15.86
4.5WHF 26.5 22.5 4.14 10 28.98

Bottom line:  There is not much heat loss through a well insulated whole house fan damper door.  The question that you SHOULD be asking is: “How well sealed is the whole house fan damper door?”

Most residential windows will have R values of 1 to 3. Another question that we get all the time is : “What is a BTU ?”

BTU stands for British Thermal Unit.

1 BTU is approximately the energy released by burning 1 paper match.

100,000 BTU’s make up one therm – that’s how you purchase natural gas, and right now that costs about $1.50

A gallon of gas has about 114,000 BTU.

European Observations

The picture at right represents some of the contrasts that  we observed on our recent trip to Europe. Outside of the room, you can see a building that is anywhere from 100 to 300 years old. Every window has shutters which have been used for years to keep noise and light out.

In contrast our hotel room (and every hotel room we stayed in) was equipped with modern windows that make North American models look primitive. As expected, the windows open along the vertical hinge, but the cool feature is that with the twist of the handle, they can be made to tilt open leaving a secure ventilation gap at the top.  When closed, the window seals like an airplane door, which makes for almost zero air leakage.  The good seal was further appreciated, considering that the street is about 2 feet from the window.

When you have a hammer…

“When you have a hammer, everything looks like a nail”

What a wonderfully simple way to describe much of our world.  I am reminded of this whenever I see people working on the “energy” problem.  Software people clearly know, that if only we wired everything up and monitored our energy use, the rest of the problem would be trivial.  Economists clearly have the upper hand, because they can describe carbon trading as the sure fire method to reduce carbon output,  increase energy efficiency, and still have economic growth.  Photovoltaic manufacturers, electric car builders, and wind farm developers are among the many queuing up at the public feeding trough.

Nothing wrong with any of those solutions.  Just bear in mind the aphorism.

By the way, our hammer is a whole house fan.

Foam Recycling Program

As a manufacturer of environmentally friendly products, it is always our goal to find new ways to be even more green in our business practices. In January 2009 we decided to implement a foam packaging recycling program to help reduce our environmental impact. Packaging_reduced

In order to ensure that our fans reach customers throughout the country without damage, they require robust polyethylene foam packaging. Polyethylene is a highly elastic and strong plastic that can withstand multiple impacts, making it ideal for shipping heavy objects such as whole house fans. Unfortunately, both the production and disposal of polyethylene, like all plastics, causes serious damage to the environment. In many parts of the country polyethylene foam is difficult if not impossible to recycle, so most of it ends up in a landfill.


The only way to reduce the hazards of plastic is to reduce the production of new plastic products. This is done by both decreasing overall demand and increasing the recycling of plastic. Our program allows us to reduce our need for the production of new polyethylene and also reduce the total amount of plastic being thrown away. We reuse the foam as many times as we can and then we recycle it, ensuring that the foam returned to us does not end up in a landfill.


It is immensely satisfying to us that we have had great customer response to this program. Almost 1 year  into the program and we have an average return rate of 42%, and the numbers are constantly increasing! My personal goal is to achieve a 50% return rate by next Spring, and with the return rates always increasing, I believe we can easily achieve this goal.

We owe a big thank you to all of our customers who have supported this program. We would also like to send out a hearty thanks to UPS, who has kindly begun waiving label printing fees and also begun offering us a discount on our return packages. With the help of UPS, our foam recycling program has been made more financially viable for us to continue in the future.