Now Introducing… Solar-powered Whole House Fans!

Not really. The headline above is a little tongue-in-cheek. Readers of this blog will know our fans are designed to be run at night, when cool outdoor temperatures can be drawn indoors. Since photovoltaic cells can’t generate electricity at night, directly powering a whole house fan with solar generated electricity isn’t possible—unless, of course, one wants to run their fan during the day, which would heat the home rather than cool it!

We do, however, frequently receive calls from homeowners wanting to know if they can run a whole house fan directly off of their home solar array. We wish they could. Because they’re a more efficient substitute for mechanical air conditioning, whole house fans greatly compliment solar by reducing the size of array needed to provide the same cooling. But again, photovoltaics don’t work at night.

To operate a whole house fan with electricity generated by a solar array, homeowners need some sort of energy storage device that would allow them to store electricity they generate but do not use during the day. Then, this stored electricity could be drawn down through the night to power the whole house fan.

In short, they need a battery—which is why we’ve followed Tesla’s recent announcement of their new Powerwall home battery system with great interest. Home battery systems have been available for some time now. But they have never been as prominent in the popular discourse as they are now, makings this the ideal moment for a blog post “back of the envelope” analysis about using a home battery to operate an AirScape fan.

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Aloha… Whole House Fan & Solar Attic Fan Rebates from Hawaii Energy!

We at AirScape are happy to learn of the first whole house fan rebate available in Hawaii! (link) Offered to Hawaii Energy customers, the rebate offers customers $75 back on a whole house fan purchase and $25 back on a solar attic fan purchase. It’s great timing for this type of incentive, because summer is approaching and these efficient natural cooling solutions can help reduce your need for A/C – thus saving you money and sparing the environment.

Get them while they last, though, as the application states it is effective for purchases made from April 1st to June 1st, 2011. We hope for more rebates to roll out soon in Hawaii for all sorts of energy-saving and energy-producing technologies with the recent progress of SB 1520, which would have been left to die if it weren’t for a great showing of public support. Thanks to Hawaii Energy and the Blue Planet Foundation for their efforts to help secure a clean-energy future!

financial value of green

How much do ‘eco improvements’ such as whole house fans add to the value of your real estate? With a little bit of math, and some financial formulas, we can figure that out. Here is an example of a homeowner who installs one of our 4.4e WHF models. Let’s take a conservative value for energy savings ($500 per year), with a desired return on investment of 8% (you could not get that anywhere else..). What we do is use the financial formulas to figure how much money would need to be invested at 8% interest in order to return $500 per year, over the life of the whole house fan. At the end of the 20 year life span, we assume (also conservatively), that the WHF has no remaining  value.

Plugging in the numbers: i = 0.08; n = 20; Savings per Year = $500, yields Present Value = $4909.

Wow! That means that if you paid up to $4,909 the return on investment would be 8%. (we don’t charge that much for the 4.4e…)

Saving Energy is a damned good investment. Who woulda thunk ?

Kohilo* Returns Home

With a warm climate year round and relatively cool nights thanks to the ocean breeze, the state of Hawaii is a perfect place for AirScape Whole House Fans. Not only is the weather ideal, but the cost of electricity is sky high. The average cost for electricity in August 2010 in Hawaii was 28.59 cents per kilowatt hour. Compared to the U.S. Average of 12.02 cents during the same month**, it is obvious that going green by lowering electrical use is not as much a choice as it is a financial necessity for many residents of Hawaii.

Armstrong Builders has partnered with the DHHL (Department of Hawaiian Home Lands) to build affordable green homes in a state where affordable housing is virtually unheard of and utility rates are astronomical. The communities “Kumuhau” and “Lai Opua Village” both include AirScape Kohilo-e Whole House Fans (the Kohilo-e is a special limited edition model using the highly efficient ECM technology designed specifically for Armstrong Builders for use in their projects). Even with the high electrical rate, the fan only costs an average of 5.7 cents an hour on high speed and 1.4 cents an hour on low speed. Compare that to an extremely efficient 2 ton Air Conditioner, which is going to cost 68.5 cents an hour on average, and it’s easy to see why our whole house fans are so beneficial in Hawaii.

As Kaulana H.R. Park, director of DHHL and chairman of the Hawaiian Homes Commission (HHC) said, “Reducing living costs is one measure of a sustainable lifestyle and as native Hawaiians, living a sustainable life is what we strive for.”***

We’re glad we can be a part of this move towards greater sustainability in Hawaii.

*Kohilo is Hawaiian for “a gentle breeze”

**For average electrical rates by state, visit the Energy Administration Website.

***DHHL News Release.

is the recession over

Being an engineer, and full of opinions, people often ask me when this recession will end. Good question. In fact, a friend of mine just asked me that. Luckily for him, we were bicycling uphill, and I could not devote my remaining breath to verbalizing the solution.

Well, after a bit of thinking I realized that maybe, just maybe I have a metric, or at least an indicator for when our economy starts to grow.

It comes down to this.  When institutions and organizations return to increasing productivity, then we are on the road to increasing wealth. Why should this simple metric be more important than an economist who knows way more math than most of us? Well, I’m going to bring in some handy engineering tools:

  • The Control Volume.  This is a great concept because it’s so simple and elegant. Draw an imaginary surface around whatever you are studying. Now, the increase in whatever you are measuring has to come from either greater input or less output. A corollary of this is “garbage in, garbage out”.
  • Some basic calculus.  All you need to know is rate of change.
  • BS detector. (based upon proprietary common sense algorithm)

Let’s go over some social institutions and I’ll grade them. The grade up/down is based on whether I (using my tools above) judge whether the institution is providing more benefit to society than the year before.

Education ‘Is our children learning?’ Sure, but the evidence says they are learning less, and it’s costing more money from kindergarten to univeristy.
Medical Way out of control. We’re sicker, life expectancy is not rising, and it costs more every year.
Legal Peleeese.We spend $865+ billion on our legal system. That’s a lot of money.  And even if that is good value, is it getting better for us, the public?
Military A necessary cost, but again, how much safety did we buy this year for $700,000,000,000. And next year will be more safety for less money?
Electronics A rare winner. Way better each year for way less money. Only problem is we let the kids have phones, computers, games, and now they think they’re adults.
Financial Apparently they used to do something. (like your appendix). Currently the control volume concept and my BS detector determines that the financial industry takes 7% of U.S. GDP and gives us what? (hint: bonuses)  I have sympathy for these guys. How can you improve when you gamble invest this amount of money each year?
Manufacturing Whatever is left in this country generally provides good wages, and if they are still in business, have been outperforming themselves year after year. Of course, this is the one group that we chose to outsource – damned producers!
Science A winner. Science pays off. Scientists work cheap and they find things that we can make money from. Thankfully we are busy cutting off funding.
Religion This would be hard to measure. So I’ll say that their effect on society is stable.
Transportation Airplanes, car travel … definitely not improving.  Apparently it’s too expensive to invest in fast trains. Nope.  This sector is not  increasing in productivity. Scratch that. Transportation is so bad it couldn’t get worse, unless of course we ran out of oil….
Public Safety Of course it got better. We have 1% of our population in jail. That costs a lot of money, and the prison population is getting older.Guess what, they need more medical care too!
Energy Still on the oil program. Here’s the plan!. Wait until they raise oil prices, then we panic.

So, there’s the theory. When these groups/industries/institutions  stop feeding and start producing, then we create wealth again. And in case there are any misconceptions, here is what wealth really means to us:

  • Jobs
  • Clean environment
  • Public Safety
  • Education
  • Retirement
  • and last… Stuff.