Disqus - Latest Comments for meganwhite

Re: My "A-Ha!" Moment

meganwhite — Mon, 14 Feb 2011 09:47:16 -0000

Thanks for reading, Trish! I completely agree: It was great to see the creativity that went into this year's event. I can't wait for 2012!

Re: My "A-Ha!" Moment

meganwhite — Mon, 14 Feb 2011 09:44:30 -0000

Thanks for your interest! I can't wait to check out next year's event!

Re: Making a Case for Reduced Classroom Ventilation

meganwhite — Fri, 17 Dec 2010 13:34:25 -0000

Thanks for your interest! The author's response: "The outside air cfm is based on 7.5 cfm/ student x the actual number of Students in that classroom. Then add up the classrooms assigned to a specific air handler and that is the amount outside air brought into the system."

Re: Fog-Humidification Units Play Major Role in Facility’s Cooling-System Improvements

meganwhite — Thu, 14 Oct 2010 10:07:03 -0000

Thanks for your interest. Check out this response from Mee Fog:

The reader makes a valid point. If an RO system were installed originally, they may not have had such a problem with the steam units. When we were brought into the fold, we asked them to send us a water sample for testing and we recommended RO water for the application.

The steam system manufacturer suggested to replace the units all together (although they were only 5 years old) because the replacement parts (i.e. tanks, heat exchangers, etc…) were similar in price. They went on to suggest the improved microprocessor performance and new warranty would make this the best decision.

Mee provided a system comparison study which included the fog system cost, installation, water treatment, maintenance, and make up energy required versus replacing the steam units, and we projected a payback in 7 months. Actual conditions later showed an 8 month payback (not too bad).

The AHU’s already had the preheat capacity available to offset our evaporative cooling, was able to return about 15% of the conditioned room air, and plenty of room inside for our system so the retrofit was fairly simple.

For this project, even if the steam system was working fine, it would have still made sense to replace them with the fog system because of the energy savings.

Thanks for the questions/comments.

Regards,

Eric Adamson
Sales Manager-Mee Fog

Re: Pressurization Control in Large Commercial Buildings

meganwhite — Wed, 04 Aug 2010 09:28:24 -0000

The author, Dave Moser, replies:

"Good question. On the projects we've worked on, we've done custom spreadsheet calcs for estimating the energy savings. I'm not aware of any research or calculation templates that have been developed in detail.

Most of the times, the energy savings related to optimizing building pressurization control comes from reduced fan speeds, or from reduced infiltration (heating / cooling loads reduced). It's a tough one to calculate the savings for, though. Oftentimes it's a measure with a low implementation cost, so Owners may be ok with estimating the savings up front based on a rough calc, then truing up the savings estimate post-implementation based on measured data (e.g., measured fan speeds).

There are papers like this one:

http://resources.cacx.org/l... <http: resources.cacx.org="" library="" holdings="" sellers_aceee2004.pdf="">

But I haven't found anything specifically addressing quantifying the savings related to optimization of building pressurization. Might be a good research topic.

Am glad to hear you made it to NCBC in Chicago! I thought it was a great conference, was nice to connect with so many people in the industry.

Regards,

Dave Moser, P.E."

Re: Unit for Electricity Savings Named After Godfather of Energy Efficiency

meganwhite — Thu, 18 Mar 2010 11:11:14 -0000

Hello, Bob. Thanks for your interest. The lowercase "w" in "kwh" is simply an editing-style issue. I appreciate your attention, however. The devil is in the details, as they say.

Cordially,
Associate Editor Megan White

Re: Pressurization Control in Large Commercial Buildings

meganwhite — Mon, 15 Mar 2010 11:17:59 -0000

The author, Dave Moser, responds: "Good point about stack effect. The article does not specifically address stack effect as it relates to building pressurization. The strategy you’ve suggested – volumetric synchronization – is another method for pressurization control, and was mentioned in the article. This could be the best strategy for tall buildings. However, depending on the situation, it could be difficult to retrofit into an existing system due to space requirements of the airflow measuring stations."

Thank you for your interest.
Associate Editor Megan White

Re: Pressurization Control in Large Commercial Buildings

meganwhite — Mon, 15 Mar 2010 11:16:17 -0000

The author, Dave Moser, responds: "It’s true that wind can have a great effect on building pressure, and that high rise buildings have additional challenges that must be addressed related to building pressurization. I’d be hesitant to write off building pressurization systems due to these challenges, though. Adequate shielding from wind effects (as best as possible, at least), calibrating static pressure sensors, and proper tuning of control loops are all necessary and achievable for an active building pressurization control strategy to work properly.

Re. return fans, previous research and case studies have shown that return fan operation does indeed have an effect on building pressurization."

Thanks for your interest.
Associate Editor Megan White

Re: Grooved Mechanical Pipe-Joining Systems

meganwhite — Thu, 19 Nov 2009 18:53:52 -0000

Thank you for your interest. The author responds:
"Please note that this information relates to the Victaulic grooved couplings only. For standard HVAC comfort systems, Victaulic offers couplings rated up to 1,000 psi, however for specialty applications, such as high pressure sludge lines, back fill paste lines in mines and high pressure cooling water lines in mines, we offer couplings with pressure ratings up to 4,000 psi.

For standard hot water systems, Victaulic offers products rated up to 250 degrees F, however for specialty applications, such as dry heat, air without hydrocarbons and certain chemical services, we offer products rated up to 350 degrees F."

Re: Fire- and Smoke-Damper Control

meganwhite — Thu, 15 Oct 2009 08:25:44 -0000

Thank you for your interest. We apologize for the oversight. The artwork has now been posted.

Megan White
Associate Editor
HPAC Engineering

Re: Regenerative Dual Duct: A Case Study

meganwhite — Fri, 09 Oct 2009 09:22:50 -0000

Thank you for your interest. The author, Mark Lentz, responds, "The reader clearly read the article and picked up on the point. It is not a mistake. This is a good question that deserves a full and complete answer.

There are two usual reactions to this:
The most widespread observation would be, "It can't be done!", and they would be wrong. This is because few engineers have been properly educated on what evaporative technologies can actually do and most of what "they" know is really disinformation. It would also raise the interesting question, "How did they air condition before they had cooling coils?" And, they did it for decades. In fact, several major manufacturers were offering "spray coil dehumidifiers" as standard equipment lines well into the 1980's and 1990's.
The second is, "How did he manage to pull it off?" Direct evaporative cooling equipment can be used to dehumidify. They can be used to displace the need for a cooling coil, to eliminate the parasitic fan losses they impose on a system over the course of a year, and they can be used to reduce system noise levels.

The strategy goes back at least as far as the fundamental research performed by Dr. Willis Carrier, Ph. D., P.E., the man widely conceded to be the "father of modern air-conditioning." This work, "The Contact-Mixture Analogy Applied to Heat Transfer with Mixtures of Air and Water Vapor," was published in the ASME Journal, 1937, Vol. 59, pp. 49-53. This brilliant paper, only a few pages long, directly led to the development of cooling coils and defines the mathematics of both cooling and evaporation processes are defined in the paper. All of Carrier's research was performed on evaporative cooling equipment.

The short answer is that evaporation and dehumidification is the same process. The process is driven by the difference in vapor pressure between the air and the water. If the water temperature being put over the evaporative media is below the dew-point temperature of the air, moisture will migrate to the water from the air where it will condense and convey to the water the vapor's heat of vaporization. This is accomplished by chilling the water delivered over the direct evaporative media.

This technique need to be applied with care. Anyone trying to apply this technique needs to make sure that they observe the necessary mass-energy balance and not over-irrigate the media. Over-irrigation can cause the media to disintegrate. Multiple tiers of media and media depths of 3-ft or greater may be required. The water temperature leaving the media is a direct indication of dew-point temperature. The evaporative media manufacturer should always be consulted.

This technique offers major advantages over cooling coils. The energy conservation benefits of direct evaporative cooling become automatically integrated with air conditioning and fewer devices are required to effectively accomplish dehumidification. Thermodynamically, the conditioned air can not be super-saturated. Furthermore, precision humidity control can be provided using waste heat energy during the heating season. The air passing through the system is scrubbed of both particulate and gaseous contaminants improving IAQ. Independent testing performed on 8" deep media at the University of Aachen, in Germany, found that this technique not only effectively removed about 75% of all bio-organisms from the air, it also did not reintroduce them into the air even when the sump water was significantly contaminated. Greater media depth increases contaminant removal effectiveness.

Both major public high schools in the City of Wausau have Regenerative Dual Duct Systems. Wausau West High School (313,000 sf) still has a couple, but those are typically DX coils serving only three systems. Wausau East High School (334,000 sf) is a brand new facility. There, the air handling systems there were designed without either cooling or heating coils. Both facilities use 100% outdoor air and are fully air-conditioned.

Mark S. Lentz, P.E."

Thank you,

Megan White
Associate Editor
HPAC Engineering

Re: The Benefits of VFDs on Cooling Towers

meganwhite — Tue, 29 Sep 2009 11:29:03 -0000

Thank you for you interest. The author of this article, Joe Koepke, replies, "In a standard HVAC application, a cooling tower cools water that is around 95F to around 85F. So, if we use a wet bulb (WB) temperatures of 70F (could be 80F DB at 60% Relative humidity), the fan will probably only need to operate at a minimum since there is a big enough temperature difference between outside air (70F WB) and the 85F exit water temp. Now as that temperature delta closes, the fan will have to work harder to assist in exhausting more heat. A typical tower design has a 7F approach. The approach is the temperature delta between the exit water temp and the outside air WB temp. This would mean that the tower is designed for 78F WB. The cooling tower fan is designed to maintain 85F exit water at an outside air temp of 78F WB.

It is true that the efficiency of towers and their design vary depending on where they are in the country. On average, a cooling tower fan operates at 30% power, 80% of the time."

Thank you,

Megan White
Associate Editor
HPAC Engineering

Re: Finding Energy Savings With a Biomass Boiler

meganwhite — Tue, 08 Sep 2009 09:26:16 -0000

Thanks for your interest. One of the authors of this article, Michael Daskalakis, writes, "The medical center in our project currently burns wood chips only. According to the manufacturer of the installed equipment, the system can burn any biomass waste that meets the moisture content requirements of 6 to 60 percent measured on a dry basis. Information from their Website states that you can convert biomass waste to energy. Biomass gasification fuels for a CHIPTEC wood-burning system include: wood chips, sawdust, shavings, clean bio-fuel, agricultural and food-processing residue, pallets, paper pellets, railroad ties, and other biomass waste covering a wide range of moisture contents. Fuel delivery systems handle products that are sized 2 in. by 2 in. or smaller. From Honeywell’s experience, the local air permitting agency would need to approve the fuel type being considered. Some areas of the country may not allow garbage or construction waste to be burned."

Megan White
Associate Editor
HPAC Engineering

Re: Becoming a LEED-Accredited Professional

meganwhite — Tue, 08 Sep 2009 09:19:26 -0000

Thank you for your interest. The author of this article, Peter D'Antonio, writes, "LEED professional accreditation has recently changed and expanded, and there are some eligibility requirements. See this link for requirement by credential: http://www.usgbc.org/Displa...

Megan White
Associate Editor
HPAC Engineering

Re: Selecting Small Condensing Boilers

meganwhite — Tue, 08 Sep 2009 09:16:08 -0000

Thank you for your interest. The author of this article, Peter D'Antonio, writes, "It will depend on your utility rates, but, in general, select the fuel source that is least expensive. Also, you already have a propane tank, so a propane boiler may be the least expensive to install. If you have existing equipment that works and is not costing you an arm and a leg to operate, you may want to keep it. If you choose a condensing, modulating boiler, you can size it big enough to handle the DHW when you replace the water heater in the future. Good luck."

Thank you,

Megan White
Associate Editor
HPAC Engineering

Re: Maximizing Small-Boiler Efficiency

meganwhite — Tue, 08 Sep 2009 09:11:05 -0000

Thank you for your interest! The author of this article, Peter D'Antonio, writes, "Although return water is lowered, the building load is also less; therefore, there should not be a need to increase pumping power to meet the lower load. Each building responds differently, and the reset strategy will vary from building to building; therefore, the reset strategy will require fine tuning. There are also rouge zones which may not be satisfied, even at higher heating water supply temperatures, so it is worth considering removing the few worst-case (underheated) zones from the reset strategy if possible."

Megan White
Associate Editor
HPAC Engineering

Re: Becoming a LEED-Accredited Professional

meganwhite — Tue, 08 Sep 2009 09:04:36 -0000

Thank you for your interest in HPAC Engineering. The author of this article, Peter D'Antonio, writes, "The LEED reference guide is a valuable resource; also, the USGBC Colorado chapter has a study guide, and Cascadia has flash cards. There are also USGBC-sponsored training classes that may be helpful."

Megan White
Associate Editor
HPAC Engineering

Re: Multiparameter Demand-Controlled Ventilation

meganwhite — Mon, 31 Aug 2009 15:02:45 -0000

Thank you for your interest! For more information, please contact Dan Diehl, vice president of sales and business development for Aircuity, the company that makes the OptiNet system. Dan can be reached via e-mail at ddiehl@aircuity.com.

Re: Becoming a LEED-Accredited Professional

meganwhite — Mon, 27 Jul 2009 10:35:29 -0000

Hello, Ashim. Thank you for your interest in HPAC Engineering. If you are not already aware, this article was published in November 2004. For more recent information on this topic, be sure to check out our October 2008 Engineering Green Buildings column, “LEED Evolution, not Revolution” by Brendan Owens, PE, LEED AP, of the U.S. Green Building Council.

Thank you,

Megan White
Associate Editor
HPAC Engineering