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Higher Elevations Company “Our business is founded upon helping people help themselves” |
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To our valued clients…
You might have expected that our rates would increase in this day of soaring fuel prices and runaway inflation. It’s true that costs have nearly doubled since 1997 and taxes accordingly, along with them.
But… you chose us for our ability to diligently ferret out ways to keep your systems efficient and your costs down. We are among those costs and our rates are the only element of today’s economy that we can control.
So there will be no increase to our rates.
Someone once said ‘We make our money the old fashioned way… we earn it’. Wow! What a great way to conduct business! Hopefully Higher Elevations company can always live up to that standard because that’s how we spell success.
Our mission statement as it has evolved to today is to ‘live life as if it were art’. Not all artists will find this an easy path but when it’s done right… it’s a beautiful thing. God has given us a great canvas. So thank you for being part of it.
James S. Hall Higher Elevations Company |
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Higher Elevations Company Springdale, Washington Copyright © 1993 ~ 2010 All rights reserved. |
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Higher Elevations Steve Hall - Consultant P.O. Box 263 Springdale, WA 99173 Contact Email
HE Work Calendar 2010
Economizer dampers
PCT Chart Download
Calendars · Year Index 1 · 01 Sunday · 02 Monday · 03 Tuesday · 04 Wednesday · 05 Thursday · 06 Friday · 07 Saturday · 08 Sunday Leap · 09 Monday Leap · 10 Tuesday Leap · 11 Wednesday Leap. · 12 Thursday Leap · 13 Friday Leap · 14 Saturday Leap |
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IAQ Theory 101 ‘In theory, theory works, but in practice it is too theoretical…’
Ok, so we might just as well start off by getting into it over ‘that which should not be left behind, when doggie goes’. I’m speaking of Indoor Air Quality, or IAQ. Before it’s arrival, we all just died to get to work! According to the experts, we also died while we were there. Throw in a few lawyers and we have ample reason to take up finger painting, pottery and gardening professionally.
It’s the ‘new math’, but before we get to that… what ever happened to the old math and why was it in place before?
Enter the diffuser, delivering air at 300 CFM, (cubic feet per minute), times four into a classroom, which will be our model. A fan sized to deliver 1200 CFM was placed thoughtfully upstream at the mouth of the ductwork. Heating and much later, cooling was sized adequately to serve the predicted needs of air delivery.
Initially, 10 percent outside air was picked as an ideal minimum, because at 63 degrees (Fahrenheit) the flow would be perceived as introducing fresh air without significant cooling. This would be theoretically, the resulting temperature of a 70 degree room, introducing 10 percent outside air at 0 degrees F. 0.9 * 70 = 63 degrees (I have an Excel™ chart you can download, or receive in email)
Often times we have seen mixed air reset set points range from 65 to 55 degrees, based upon room cooling demand. Therefore, we would quite often introduce much more fresh air at warmer temperatures. For example, at 65 degrees outside air we would need 100 percent outside air to achieve our 65 degree set point.
But once it got warmer than the room outside, (which should be the litmus test), we closed the dampers back to minimum (10%).
Then one day, someone left their home, which had 0% air exchange by the way and found themselves feeling sick, obviously due to the minimal air exchange at school, where they spent 25 to 30 percent of their time, not considering lunch and recess.
Experts and politicians and expert politicians were called upon to arrive at an ultimate conclusion, which would later be backed up by reasoning and thought process. And again, ‘man, could fix it’!
Fifteen CFM per student would do the trick, which equaled out to seven students and a teacher, per classroom, for our legacy design air handling unit, delivering 120 CFM at 10 percent. Maybe the economists won’t notice the change and the teachers will love the class size.
But they did and weren’t impressed saying, “no, that will never do”. So it was decided to introduce 15 CFM per student, times 30 students, that is to say 450 CFM of ‘fresh outside air’.
Of course, that didn’t work so hot in practice, because 450 is 37.5 percent of 1200 CFM. Applied to the same physics that originally dictated 10%, our mixed air temperature would drop to about 44 degrees, when it was 0 degrees outside. This could be interpreted as ‘cold’ by some folks. Our heating apparatus, originally designed for 10% may have a hard time keeping up with the change and the states energy budget was way north of the charts.
Enter the ‘grandfather clause’… that would be the father of the father, of Santa Clause. You don’t have to meet the requirement, if you can’t meet the requirement. But, oh yeah… they kind of forgot to include that clause, which put the entire balance of compliance and function, on the shoulders of operations.
Another development further complicated matters. It was deemed that on/off style heating and cooling offered advantages over the central hydronic heating and cooling systems. In some cases, a single stage of heat was designed to overcome this deficit of calories at the mixed air. Additionally, the ratio was sometimes modified by increasing the fan size, to say 2000 CFM, for example. Now this mind wave was of epidemic proportion! Going back to our chart, now with an encouraging 22.5 percent of outside air, we achieved 54 degrees, an increase of 10, at the mixed air. And let’s not forget our original mixed air reset… one degree below effective cooling, at 54 degrees.
Our new supercharged heat, could easily raise that to a more than adequate temperature, say 110-120 degrees? Now this was appreciated by the class and the teacher with the megaphone, trying to teach over the inrush of 500 CFM per diffuser. For three minutes, or often less, they were blasted with heat and during the off cycle they were crystallized, by 54 degrees of cooling at force four wind velocity. The story gets worse during the cooling season, which I will not bore you with.
So for the past ten years, engineers have had to re-think the wheel, some quicker than others. Terms like IAQ monitoring and heat recovery have found their place on calculators that replaced slide rules.
Heat recovery retrofit is big and ugly… and necessary. Multiple stages of temperament will replace single stage heating and cooling, at a greater cost. Class sizes and schedules may be included. IAQ control cost money, which a public will have to provide. Already, priority conflicts exist in specifications, such as “introduce fresh air to control the air quality, but do not let the mixed air temperature drop below 50 degrees”. Some controls have fixed programs, which can’t cut the new mustard. I offer this solution to the industry, for legacy systems, (those designed for 10% minimum outside air).
It is not practical, or possible to introduce the 37.5% outside air, during ventilation cycles (when the heating and cooling are off). But, take a look at what can be done during the heating and cooling cycles. Often, you will be able to introduce more than 37.5% during these cycles and drop back to lesser minimums during the ventilation cycle.
The overall effect will meet, or exceed the required number of air exchanges per hour. You will heat with cooler air and cool with warmer air, which will increase the duration of the heating and cooling cycles and the introduction of fresh air along with them. Your occupants will notice a more even level and duration of comfort. Your equipment will cycle less often.
And finally… your energy budget will still increase, perhaps not quite as much, but then… no plan is perfect. Lock the Architect in the closet and tell the accountant you want the big ugly heat recovery system added imposingly down the side of your, once beautiful, building. Just make sure the make-up air unit, working in conjunction with the heat recovery, has multiple stages of tempering control, or is analog in nature, (analog = varying gradually between temperatures, as opposed to “on/off” control).
I see IAQ as an industry that wasn’t ready for itself. But, it’s getting there over time and it is encouraging to see new construction making better use of ‘free’, (previously discarded), energy. Oddly enough, in some cases IAQ has breathed new life into some of the older analog hydronic systems, largely due to the need for multiple stages of control at an increased cost.
One day, given proper education, economy and environment will meet face to face and have it out, once and for all. Until then… we have IAQ dictated by the passion of environment, without respect to economy, for as long as we can afford it. This would no doubt change, if the public were made aware of the cost increase, on a cents per CFM basis. For example, ‘oh let’s say… 2 cents per CFM… quoting the comedian Ron White… “let’s just say”.’
Questions and comments to… Hey! Do you think we should have a page dedicated to responsible questions and comments? Sounds like a very good idea to me and so shall it be.
And finally… in the face of you know it all experts… “vacuum sucks”, so get off of your high horse about an over abundance of lower pressure! It doesn’t fly here… this is ‘my site’! Got it? And if I want to say that the distance between to points on a line is the difference of distances that exists between each point and infinity, upon that line… I will, so there!
At the end of the day, the apples and oranges are to be eaten. And what is a geocentric orbit anyway? I have seen those cars and highly doubt they could even break free of Earth’s atmosphere, much less maintain a fixed orbit over one point on the surface of the planet. ‘Don’t mind me… I’m just a control freak’
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