Friday, August 31, 2012

The Future of Air Conditioning

An article from the New York Times was sent to me recently. It described the problems with the energy use of air conditioning in the future as well as attempts to conserve today. Here are a few interesting facts from the article.

- A Japanese study concluded that operating an office a few degrees above “optimum” (72-75°F) resulted in a measured decrease in productivity of between 2 and 5%. If salaries run $200/SFY (square-foot-year average in developed countries), and one loses 2% productivity, that is $4/SFY. It is estimated that the average cost to heat and cool a building is about $2/SFY. It is easy to see that operating a building above a desirable setpoint is a losing proposition.

- In Japan, with the lack of nuclear power, some buildings were operated at 80°F+, to save energy. Occupants were using fans to be able to continue to work. Data showed energy use was greater than when operated at more ideal temperatures! It turns out that many buildings are mostly made up of interior spaces and the setpoint is pretty much independent of the temperature difference between the inside and outside, but wholly dependent on the internal heat gain, which must be removed when outside temperatures are above whatever setpoint is established (where outside air cannot be used to cool a building).

- Air conditioning is directly related to productivity in hot climates, where most humans now live. It was estimated that a billion (yes, a billion) folks will be entering the consumer market in the next 15 years. It is further estimated that one of their first purchases will be an air conditioner. If this proves true, providing power to run those AC units will be a real challenge; conservation and thoughts of “carbon footprints” in the US will pale in comparison to the expected increase in just over a decade.

This should be an interesting decade...

Authored by: Dan Int-Hout, Chief Engineer Krueger

Monday, August 20, 2012

Infrasonic Noise

I have been having conversations with a retired acoustical engineer in upstate New York. He has been working with folks who have been disturbed by nearby wind farm towers producing infrasonic noise.

Recent studies show that infrasonic noise is detected by the inner ear. The main unknown is our understanding of how we react to the infrasonic noise that is detected by the outer hair cells in the cochlea. It is obvious that the inner ear is much more complicated than acoustical practitioners have been taught. The old saying, "if you can't hear it, the noise can't hurt you," just isn't true.

We know that we have been hard-wired to protect ourselves when we receive certain sensory perceptions. For instance, why does one third of the population get sea-sick or experience motion sickness? What is the root cause?

If you go to Wikipedia, you will find: We take all our information from the world through our senses, and many times that comes from multiple inputs. For instance, in the case of sea sickness, the brain is processing the inputs from the following senses:

Both inner ears monitor the directions of motion in three dimensions. Our eyes observe where our body is in relation to its surroundings as well as the direction of motion. Skin pressure receptors, such as those located in the feet and seat, sense in what direction the gravitational pull affects our body, in other words: “What side is up?” Muscle and joint sensory neural receptors report which parts of the body are in motion and in which relative direction.

When feeling motion but not seeing it (for example, in a ship with no windows), the inner ear transmits to the brain that it senses motion, but the eyes tell the brain that everything is still. As a result of the discordance, the brain will come to the conclusion that one of them is hallucinating and further conclude that the hallucination is due to poison ingestion. The brain responds by inducing vomiting, to clear the supposed toxin.

In a similar manner, I don't think we understand why we react to excessive low frequency and infrasonic noise the way we do. One thing worth remembering is that in nature, when there is excessive low frequency or infrasonic noise, good things are not happening. When our forefathers and foremothers heard and felt the rumbling from thunder, tornados, and earthquakes, they knew it was time to head back to the cave. We are the survivors of those fast folks who made it back to the cave. Isn't this what happens in evolution?

As a note, most sound meters and smart phone apps can’t register infrasound.

Low frequency sound energy can cause some folks to react negatively. HVAC systems can cause low frequency sound (typically large air handlers and turbulence), leading to complaints, of which solutions are hard to come by. It is best to design systems right to avoid these kinds of problems. So to go back to the conversation with the engineer, if you have a nearby wind tower, you may understand why you or someone in your family may be bothered by its presence.

Authored by: Dan Int-Hout, Chief Engineer Krueger

Friday, August 10, 2012

Bike Week!

I spent the last week up at the Sturgis Bike Week, where I again rode with a couple other HVAC industry guys. One was a mechanical equipment rep, the other a veteran design engineer, both from Omaha. Not surprisingly, we discussed our business. Here are some of my observations and take-aways.

1.) The economy has had a huge effect on the rally. On Monday afternoon, there were only a dozen bikes in the parking lot. Usually there are a hundred. Hewlet was as light as I have seen in 10 years and there was even available vendor space at the HD store in Rapid City. Most of the folks I met were from states surrounding South Dakota. I didn’t see a single bike going North on my way up the Thursday before, which was very unusual.

2.) We discussed specifications, which was the subject of my last blog. The rep said he sees nonsense “flawed” specs all the time. The engineer said that they don’t have time to clean up all the hundreds of pages of specifications. What ends up happening is that the rep just bids what they think the engineer actually wanted. Needless to say, a close relationship between the rep and engineer is ever so important.

3.) Ventilation air is the load. Minimums, tied to incredibly low space loads, are often too much air at 55°F. Strategies to raise the discharge in some zones needs to be considered, especially when the perimeter may well need 55°F air. The DOAS “chilled” box I discussed earlier is a great solution to this quandary. The equipment rep who sells the DOAS rooftop supply units got a bit excited and will be calling our rep to look to a partnership!

4.) Adjusting diffusers and placing them properly continues to be last on the list of concerns of most engineers and contractors. Balancing nightmares are real. Occupants who experience non-uniform environments are often very unhappy; productivity will suffer. None of the three of us could see a solution besides increasing awareness of the need for proper air distribution design. WE know how to, but most don’t.

5.) Acoustics will continue to be a big deal. I just got some info on ‘infrasound’, very low frequency noise. It has interesting effects on the inner ear. I’ll talk about that next week!

Authored by: Dan Int-Hout, Chief Engineer Krueger