The Texas Experience

 Once again it has been many months since I have posted anything. Since then we have obviously been dealing with the pandemic as well as learning the impact of a weak cybersecurity policy. Although I could probably write a novel regarding the cybersecurity issue there are many more expert people on that topic.

Today I want to go back to the original purpose of this blog that was to capture and share some random thoughts related to the industry.

One of the latest events that started the wheels turning in my head again was the partial shutdown of the Texas electrical grid. Again there are experts in grid design and operation who can, and have, discussed this event in great technical detail. There has also been the, now expected, political finger pointing and partisan debates. But I wanted to share some of those random thoughts about what this "localized" event might teach us.

Many engineers, especially those involved in critical HVAC infrastructure, are already aware of the fragile nature of the electrical grid in many parts of the US. At Mestex we provide systems to many different types of applications where a power outage could have a costly impact. Preparing for those potential failures was usually someone else's problem. The electrical engineers and suppliers of standby power systems were intended to handle the "short" periods without electrical power. Although we researched ways to integrate backup operation into our equipment the results would have proven too expensive to be marketable. What Mestex has continued to focus on is applying systems that try to utilize "site resources" efficiently in order to reduce the demands on the backup systems.

Looking at a broader picture we have seen the global trend toward "electrification". The goal, it seems, is to reduce greenhouse gases and other atmospheric pollutants that contribute to climate change. While some are still skeptical about climate change it has reached the point of a consensus among scientists around the world. Many countries and large corporations are on board with taking steps to mitigate their impact. Electrification is intended to move the source of pollutants away from the "site" where power is used to the "source" where power is generated. In theory this would allow better control of contaminants at a single point instead of at hundreds or thousands of "site" points. This would also facilitate the use of alternative energy sources such as wind generators that would be difficult to implement at the "site" level. So we have a relative rush to requiring electrical vehicles, electric residential heating systems, and even electric commercial/industrial heating.

At the same time that electrification is moving forward in areas that the average person can see there is a convergence of our ever increasing digital life with our daily power consuming life. Data centers are being built and turned on almost daily around the world. To the average person this is great as it means they are always connected no matter where they go. This also helps the electrification effort by providing the opportunity for sophisticated remote traffic management, demand control power distribution, and "smart" home appliances. But the electrical power consumed by data centers is almost mind blowing to the average person. A single, moderately efficient, small data center can consume as much electrical power as five thousand homes. Clusters of large data centers (as is common due to scale and locale) can draw enough electrical power to support entire towns or even entire less populated countries.

When these data centers or data center clusters are inserted into an already fragile electrical grid they add a strain factor that was not anticipated when the power station was designed 20 or 30 years ago. Data centers can be designed, built, and activated in months versus power stations that require years to complete. It is inevitable that a mismatch of power supply and power demand will occur.

It seems to me that part of what the Texas experience showed us is, first, electric power is critical to basic life support facilities such as water and sanitation. My second thought is that as much thought and research should be put into the development of highly efficient, "clean", "site" energy systems as into the electrification idea. Off-loading the grid with effective "site" solutions could help with the balance of supply and demand on the grid. Many large companies have already taken steps with solar arrays over their parking lots, small-scale wind generators on site, or private co-generation plants. In most cases though these are extremely expensive solutions. Their implementations have been driven as much by corporate "green" initiatives as anything.

Companies should also not lose sight of current technologies that are still viable "site" solutions and counterbalances to grid overloads. Although Mestex has transformed itself over the last few years into generating more revenue from cooling solutions than from their traditional natural gas heating solutions most people still consider the company to be a gas heating company. In applications that require large amounts of outside air, or that simply move huge amounts of air that must be heated, a modern and efficient natural gas heating system is a much more "climate friendly" "site" solution than an equivalent electric heat "source" solution. Mestex can provide such systems based on their decades of manufacturing such systems and research into optimized digital control of such systems. 

 Engineers and companies can meet their goals of responsible environmental stewardship by keeping in mind the contribution of "site" solutions as they also work to meet the transition to greater electrification.

HVAC's Unseen Protectors

As the world deals with the Novel Coronavirus I was reminded of research that I was involved in some 35 years ago.  At that time I was directly engaged in modeling airflow and temperature profiles using Computational Fluid Dynamic (CFD) software for a major air distribution products company.

While we used CFD modeling for a wide variety of complex air distribution problems the case that came to my mind this week was modeling an infectious disease isolation room for the CDC.  The challenge was to design a negative pressure isolation room that also minimized exposure of a health care worker positioned directly adjacent to the patient bed. 

The specific type of infection to be studied at that time was tuberculosis (TB).  Much like the current coronavirus, TB is often spread by droplets when a patient coughs.  A healthcare worker standing next to the patient bed was almost certain to risk exposure if the room used conventional air distribution layouts and patterns.  The correlation with today's problem is obvious.

My current company, Mestex, has been using CFD analysis for 20 years.  Although our modeling efforts have not included the case mentioned above we can apply the same techniques to create accurate temperature and airflow models of data centers, pharmaceutical storage warehouses, chocolate or wine warehouses, eCommerce fulfillment centers, or virtually any temperature sensitive application.  Much like the goal of the CDC study of 35 years ago our objective is to use modeling to optimize our product applications without the expense of full scale mockups or, worse yet, finding out about a problem after the building is complete.

The HVAC industry is continuing to refine the modeling techniques that I used those many years ago in order to create even better solutions to healthcare worker protection.  In general, when we do our jobs correctly, the end user is not aware of what is involved.  After all, you cannot "see" temperature or air so our work is "invisible".  However, the HVAC industry has a vital role in helping protect people and critical products from many types of threats.

Disruptive Opportunities

So...my last post was a bit of a downer in discussing how the current disruptions to the global supply chain were exacerbated by the computer driven, optimized, logistics models...and how long it can take to restore things to "normal" even after the disruption is under control.

But...like any disruption to the norm...there is a flip side to the disruption that creates opportunities.

The most obvious opportunity that companies are grappling with today is the huge number of "white collar" workers who are now operating out of their homes.  In the past few years there have been increases in the number of "remote" workers but the current situation has caused that number to explode.  People who had already been working remotely probably had "a system" in place to manage communications, projects, and interaction with the office but now there are many "newbies" to this process.  Because now entire departments might be working from remote locations the need to continue collaboration creates a new wrinkle.  This is providing an opportunity for consultants and software resellers to help companies implement some of the collaboration tools now on the market but probably not used to the extent that this opportunity provides.  Microsoft Teams, Google Drive and Workspace, Amazon Chime...all provide structured collaboration tools that could now see widespread adoption...and change "office work" as we know it going forward.

Another potential opportunity that could see broader adoption is autonomous delivery robots.  This technology already exists and has been deployed on educational, corporate, and hospital campuses.  It has already been tested and deployed in a few communities but, again, the current disruption to how consumers purchase grocery items suggests that entrepreneurs with sufficient capital and the ability to partner with local grocery chains could deploy fleets of small food delivery robots.  These could be especially effective within "gated" communities where mapping delivery routes would be simplified and it is likely that bike lanes already exist that could keep the robots off the main roads.

Within the HVAC industry the current disruption could provide an extra push to the efforts to create "smart" equipment that can diagnose their own problems and call for help when needed.  Using "machine learning" and "AI" techniques, combined with new wireless technologies, even equipment located in hard to access locations could receive faster and better service when needed.  Service technicians who are adept at technology could be working from anywhere.  A network of such technicians located across a region, and using some of the collaboration tools above, could provide fast and accurate service and collaborative solutions to more troublesome problems...even if working from home.

Every disruption, by definition, forces a change to the status quo that can be difficult for some to adjust to but there is also an opportunity created for those that embrace the disruption.

Hot Air Balloons and eCommerce

I live in an area that is almost ideal for hot air ballooning.  On almost any morning it is not uncommon to see at least 6 hot air balloons dotting the horizon.  Watching some the other day as they prepared for launch and then ascended it struck me that there is a basic lesson in the process that is useful to remember when designing HVAC solutions for eCommerce buildings and warehouses in general.

The obvious lesson is that hot air is buoyant and the hotter it is the more buoyant it becomes.  When prepping for launch the crews use their direct fired burners to blast hot air into the balloon causing it to fill and lift.  Once the balloon is vertical the crew fires the burners at full heat to get the balloon off the ground and on its way upward.  While in the air you can hear the burners firing whenever the balloon starts to drop below the altitude the pilot is looking for.  Short blasts produce little heat and balloon either stays stable or starts to slowly descend.  Long blasts produce more heat and the balloon rises.

So...what does this have to do with eCommerce and warehouses?  While the HVAC equipment cannot produce air that is hot enough to lift the building off the ground it can produce air that is hot enough to rise rapidly and stay near the top of the space. In an eCommerce fulfillment building with dozens of humans occupying the bottom 6 feet of the building that hot air can be a problem.

There are some HVAC companies that propose using very high temperature air to heat the entire space.  This becomes a real challenge as the hotter the air the more it wants to stay up near the ceiling.  There are a couple of ways to deal with this but both ways impact electrical operating costs.

One method is to install several large fans that are intended to pull air from the ceiling space and force it down to the floor level.  In addition to the electric power required to spin the fans this solution can also make it difficult to achieve the rack heights that are desired in the building.  There may also be structural cost implications depending upon the weight of the fan/motor assemblies.

The other method is to use the HVAC equipment fans themselves to force the hot air to the floor area.  This also requires electrical energy to overcome the buoyancy of the air. A secondary characteristic of this method is that the velocity of the air from the HVAC unit must be pretty high in order to force the air downward.  The result is a column of air moving at pretty high speed that reaches the floor in a relatively small area that can cause worker discomfort or stir up paperwork or products that are in the airstream.

Mestex has been producing a product concept for decades that overcomes these problems.  The concept is called "air turnover" and many companies have since copied the idea under different names.  The idea is simple....push warm (not hot) air into the space just above the worker level and pull it back across the floor where the workers benefit from the relatively slow moving warm air flow.  Not only does this method produce even temperatures where it is needed it also avoids wasting heat energy that collects near the ceiling with the hot air methods.

Deciding how to design an air turnover system can be challenging since the system sends air into the occupied space that also includes equipment, bottoms of racks, conveyor systems and such.  Another Mestex first is the use of Computational Fluid Dynamic ("CFD") modeling of the space to refine and optimize these designs.  CFD modeling originated in the defense industry to model aircraft performance and later was adopted by the process industry to evaluate things such as the impact of ocean currents on offshore oil rigs.  Since air is a fluid Mestex started using CFD modeling 20 years ago to assure owners that temperature critical products would be kept at the proper condition.  Mestex' use of CFD has expanded over the years to optimizing more mundane warehouse applications as well as more sophisticated applications such as data centers.  This expertise is available exclusively for Mestex customers.

So the next time you see a hot air balloon rising into the air you can appreciate the challenges of heating a warehouse or eCommerce building.

Going Vertical with Ecommerce

Vertical Ecommerce Mechanical Infrastructure Thoughts

I was emailed a copy of an article that was published in Building Design + Construction magazine that stimulated some thought.  The article spoke about the trend in Ecommerce buildings to go vertical in order to fit their large square foot requirements into a smaller footprint.  This allows the Ecommerce company to put distribution and order fulfillment closer to their customers and meet the expectations of same day and next day deliveries.

This approach is obviously appealing to developers and the Ecommerce companies themselves.  However I would suggest that it can create some difficult challenges for the mechanical and electrical infrastructure.  By reducing the footprint of the building the available square footage for mechanical and electrical equipment on the roof is also reduced significantly.  Given that most of these buildings would be built in urban locations and will require large parking areas there will also be very little room on the ground for the infrastructure.

Another characteristic of Ecommerce buildings is the clear height requirements for racking and conveyor systems.  Although the building might be as tall as a normal 8 story building it might only have 3 levels inside.  This complicates the approach to the heating and cooling of the space and creates large volume spaces that must be conditioned for worker comfort and efficiency.

A traditional approach to an Ecommerce space is to install multiple packaged HVAC units on the roof with simple overhead air distribution systems.  The challenge that I see with the vertical ecommerce buildings is the lack of roof space for the packaged HVAC solution.  Even if the square footage could be allocated for large packaged units they will need to be located closer to the center of the roof and require huge ducts to move the air toward the exterior walls (so as not to interfere with racking systems) and then down through each floor.  Branch ductwork from these large main ducts would then be needed to serve the area of each floor.  The construction costs for such systems could be quite high...if it were even possible to use the large packaged HVAC units on the roof.

Mestex has been manufacturing a solution called Air Turnover for over 20 years and it seems this might be a better fit for these vertical buildings.  The Air Turnover concept places the HVAC distribution systems on the floor close to where they are needed...a similar concept to why ecommerce is going vertical...in order to put the source closer to where it is needed.

Since Air Turnover equipment can be built with cooling coils and electric heat internally the only equipment needed on the roof would be a single air cooled chiller.  The piping system from floor to floor would consume much less space (and require much smaller floor penetrations) than the duct system and would actually perform more efficiently due to the thermal characteristics of water.  Air Turnover units would typically be mounted along an outside wall and could even take advantage of fresh air cooling by installing wall louvers adjacent to the units.  The floor space required for the Air Turnover units would not be much greater than that required for the large duct systems and Air Turnover would also not require the branch duct systems.

There are other major advantages to the Air Turnover system in the areas of performance, efficiency, ease of maintenance, ease of installation, etc...but this article is long enough now.  If you are interested in those details please contact us at www.mestex.com and we can explain the advantages in more detail.

Cool New Technology for Mestex from AHR 2017

New Graphics Tool Allows Users to "See Inside" Mestex Products.

As I mentioned in my last blog entry Mestex participated in the 2017 AHR Expo last week in Vegas.  As usual we were part of the much larger Mestek corporate display showing the industry just how broad our company's product offering can be.

One challenge with such a broad offering is that it can be difficult to explain to potential customers, and even our own reps and employees, how much of the equipment actually works.  This is true even within the Mestex division as our products cover everything from air handlers to fully packaged DOAS units, and from advanced evaporative cooling systems to steam integral face and bypass coils.

In the photo to the right you can see a demonstration of the latest corporate sales tool that helps cut through some of the mystery.

The Mestek Technologies group has developed an interactive, graphical software app that reps can use to help illustrate some of the more complicated products from the Mestex division.  This app allows the user to select from the Aztec Indirect/Direct evap system, the IFL air handling system, or the FAP packaged DOAS-capable rooftop unit.  Once selected a screen opens that shows the user the elements of the unit that can be selected for configuring a product to meet their needs.  Touching any of the components, or the complete unit illustration, will open that component and by using the "pinch-zoom" function of touchscreen devices the user can "open up" the product and drill down to detailed images of the unit.  Buttons to the right allow the user to "turn on" heating, cooling, dampers, etc and watch how the airflow in the unit changes.

Using the app at the show pointed out how clear our configurable product concept became to viewers.  It was immediately obvious that the products shown had great flexibility and adaptability to suit their application.

The app is now available on the Google Play store for download to compatible devices by searching for "Mestek" and then looking for the "Mestex" icon in that storefront.  A version for iOS devices will be coming from the Apple store in the near future.

While this app proved to be an exciting tool to the reps that saw it there is much more to expect from the app going forward.  New products will be added.  Links to technical and sales literature will be added.  Embedded videos will be added.  Integrated CFD models will be added. 

Basically, this will become the most powerful "catalog" available for Mestex products.

On The Road Again

To quote one of my favorite musicians, Willie Nelson, we are going ..."On the road again, just can't wait to get on the road again..." this time to Las Vegas for the 2017 AHR Expo. 

The Mestex division of Mestek will be sharing booth space with our sister companies in booth C1525 in the Las Vegas Convention Center.  Some people are predicting a record turnout of attendees and we expect a busy few days.

This year, Mestex will be using some new (for us) graphical display technology from the Mestek Technology group to help explain some of our newer product offerings.  Our division companies; Applied Air, Aztec, Alton, LJ Wing, Temprite, and King provide solutions to temperature, pressure, airflow, and filtration problems that can be hard to explain using a static piece of equipment.  This graphical display technology will allow us to "walk you in" to three of our products and highlight how certain elements of the products can be used to address your building or process issues.

In addition to these graphics the Mestex people in the booth can explain how our in house CFD analysis services can help optimize a solution.  Projects ranging from large e-commerce warehouses and distribution centers to data centers to "indoor agriculture" grow rooms can be very difficult to design due to high internal thermal loads, humidity levels, stratification, or pressure gradients and CFD allows Mestex to thoroughly analyze and sort out possible solutions.

So come on by the booth and, at least, say "hi".  We would love to discuss how we might help solve your application problems.

"We Have A Failure To Communicate"

For the last 15 years the Mestex division of Mestek has been building direct digital controls ("DDC") into our equipment.  We started with some pretty simple control programs on some of our more basic units.  Even these simple programs allowed the equipment to operate more effectively...controlling temperature more closely, controlling energy consumption better, and giving users more options for scheduling their system operation.

The core functions of our control systems have not changed much over the years but the features that have been added, and are continuing to be added, to improve the information available from our equipment are almost mind-boggling. 

Take the relatively simple technology of evaporative cooling.  The Mestex Aztec indirect-direct evaporative cooling unit comes standard with a DDC control package that constantly monitors outside air conditions, unit supply air conditions, unit water quality, and cooled space conditions in order to control temperature, pressure, and humidity in the space.  But that is only part of the story.

While collecting all of the data we just described and deciding how to control the unit functions the DDC processor is also collecting, and making available, a wealth of other information.  The unit can provide real time electrical power consumption and demand, real time water consumption, and constantly updated information about the operating mode of the equipment (operating hours in full economizer mode, operating hours in full recirculation mode, and operating hours in mixed mode).  The unit is also accumulating and can display daily, monthly, and annual power and water use data.

This is obviously some pretty sophisticated information from a relatively simple machine.  The same algorithms used in this unit can be applied to most of the other Mestex products and provide a wealth of management information to end users.  The larger the end user organization and the more units deployed, the more valuable this information becomes. 

But...the information is only valuable if management can actually see it.  As more and more of our equipment installations are tied to building automation or building information systems we are encountering more and more interface issues.  The issues are not matters of communication protocols since our DDC packages are designed to speak virtually every communication language but issues of human communication protocols.

What we have found in many cases is that the information, and the interface to the equipment, is turned over to an IT person who is unfamiliar with HVAC equipment.  That person is probably also very concerned about network security and has probably created firewalls that make implementation challenging.  The HVAC equipment might be working perfectly but the person on the other end who is looking at data that he does not understand will frequently interpret that the equipment is not performing as required.

So, as is often the case in life, training and communication become essential to success.  As an HVAC company we usually expect the IT person to "simply understand".  I think, however, that we should work hard to learn about networking and IT issues so that we can at least speak the same language as the person on the other end of our equipment.

Relative Humidity – It’s all relative

A Guest Article by Jim Jagers

The other day I was conducting a training class, and we were discussing evaporative cooling. Someone said they didn’t think evaporative cooling would work very well in their area because the summer temperatures were 90°F plus with 90% RH. If you were to look at many psychrometric charts, you’d see this point is, dare I say it, “off the chart”. To get a feel for this consider a steam room has general temperature of 104°F and 100%RH. At 90°F with 90% RH the heat index is 122°F. It’s doubtful the temperature and humidity are as bad at the same time as he imagined.

People generally associate high temperatures with high humidity percentages. It’s more likely that high temperatures will be associated with lower humidity percentages. At 80°F and 41%RH the heat index is 80°F. 80 degrees feels like 80 degrees. At this point there is approximately 0.009 pounds of moisture per pound of dry air in the atmosphere. If the moisture content remained constant and the air warmed to say 90°F, the relative humidity would actually drop to about 30%. Conversely, if the moisture content remained constant and the temperature dropped to 70°F, the relative humidity would increase to about 57%. This is because cooler air can hold less moisture than warmer air, and relative humidity is the ratio of the moisture in the air compared to the amount of moisture the air (at a specific temperature) can hold expressed as a percentage.

People usually think of their air conditioner as providing cool dry air in the summer, and it does because it does both sensible and latent cooling. Sensible cooling lowers the temperature we sense, and latent cooling removes the moisture. The air entering the coil may be 78°F and have 0.0101lbs of moisture per pound of dry air. The coil temperature may be 45°F and thus the leaving air may be 60°F (It won’t be 45°F because the water in the air is absorbing some of the cold). At this point the leaving air may have a moisture content of 0.0062lbs per pound of dry air. This is a significant reduction in moisture, and it is evidenced you water dripping from the evaporator coil. The leaving air is much dryer than the entering air.

However, in relative terms the air coming off the evaporator coil in the air handler has a relative humidity of 100% or close to it. Remember, cool air can’t hold as much water as warm air. When the air entering the coil, contacts the cold fins it cools rapidly. Condensation occurs when air can’t hold the moisture it contains. At this point the air is fully saturated meaning its relative humidity is 100%.

The point to this brief essay is, as I said at the start, relative humidity is all relative - to the moisture in the air and the air temperature. Warm air isn’t necessarily humid; cool air isn’t necessarily dry, relatively speaking.

Racing Into HVAC

People who know me well know that I am an avid fan of Formula 1 and MotoGP motorcycle racing.  In both of those racing series this year there is a team that is running away with the championship.  In the case of Formula 1 it is Infinity Red Bull Racing.  In the case of MotoGP it is Honda.  Unless you follow both sports and peel back the layers a little you might not realize how much technology sharing there is between the two premier classes.

 

How Controls Software Makes the Difference in Racing and in HVAC

At this point you are probably wondering where I am going with this.  After all, what does racing technology have to do with HVAC?  Well, the connection is the impact of "control software".

The Infinity Red Bull team uses Renault engines but they are not the only team that uses those same engines.  However, Red Bull has developed a "factory" version of the engine control software that limits wheel spin when exiting turns and, as a result, they are wining many races by large margins.

Honda's factory team is also not the only Honda MotoGP bike on the starting grid.  But the "factory" team has engine control software that also limits wheel spin as well as gyroscopic sensing derived from the Honda Asimo robot that allows the factory bike to apply power more quickly than the non-factory bikes.

In both of these cases the other teams using the same basic mechanical components and technologies are developing their own control software packages.  But, without the benefit of factory "inside knowledge" of how the mechanical and control elements mesh, the results are just not quite as good.

Over the last 14 years Mestex, Dallas, has been implementing factory developed digital controls on our equipment.  The control software in our products has been developed using years of field and testing experience that provides unique insights into how quickly our mechanical elements respond, how heat transfer is accomplished within our equipment, and how air moves through our cabinets.  All of that information is "baked in" to our control algorithms.

From time to time well-meaning controls contractors choose to override the factory controls, or circumvent them altogether by asking us to install their control packages, and more often than not the HVAC equipment simply does not perform as well as it could.  We try to provide as much flexibility in our controls for the contractor and end user as we believe the overall system can accommodate. 

When the "factory" controls are not used in an HVAC product the results can be the same as what we see in racing.  The product may continue to operate but it will most likely come up a bit short of the finish line.

Virtual Reality

In recent days a company created a virtual world that showed the application of a real world product.  In their case the real world product was firearms.  The object of the game was basically to kill as many of your enemies as possible using a firearm of choice.  I will not go into the sociopolitical discussion of whether or not this is a good thing.  It was financially successful for the company to develop, so from their perspective I’m sure it is considered a success.

My company also creates virtual worlds that show the application of real world products.  In our case the real world products are heating, air conditioning, and ventilation products.  The object of our virtual world is to improve comfort and in some cases actually save lives.



Virtual Building and Temperature Simulation

In our business the control of temperature and air is what our products are intended to do.  The problem is that air is invisible.  So how can we know in advance that our products will make someone comfortable or prevent a drug from becoming unusable or even dangerous.  The way we do this is by creating a virtual world.

In our business we use software called CFD, “Computational Fluid Dynamics”, to create virtual buildings filled with equipment, storage racks, and temperature sensitive products.  After this model is created we then create virtual HVAC equipment.  This virtual equipment is modeled after our real equipment.  These HVAC units are then positioned where we believe they will produce the best results.  Many times our experience provides the best result.  However, sometimes the application is more difficult.  In those cases we let the computer determine the best location and best characteristics of our product in order to provide the best result.



Air Particle Tracks through the Building

This process can sometimes take several days but the end result is a building that performs the way that it was intended to perform.  And when that happens, occupants are more comfortable or temperature sensitive drugs continue to be stored at the proper temperature.

Virtual worlds can be created for many different reasons.  We have chosen to create virtual worlds that provide great benefit to mankind.

A Simple Concept That Saves Big Dollars

Or, How a Bad Hair Day Can Save You Thousands Of Dollars...



Airflow Pattern From An Air Curtain

You have probably walked through a doorway some time in your life that totally messed up your hair…you had just experienced an “air curtain”.  So why would someone want to install one of these things if they can be so annoying?  The reason, as is most often the case, is to save money. 

“Air curtains” or “air doors” have been around for decades.  You find them on some commercial buildings up north in entry vestibules as a way to help isolate the cold outdoors from the heated indoors.  You also find thousands of them on industrial and warehouse buildings because of the large number of “dock doors” that are constantly being opened and closed.  Every time one of those doors opens, the building has the potential to lose heat to the cold outdoors…and that costs money.  Most facility managers realize this instinctively (or it was passed down from one generation to the next) but I am not sure how many have actually tried to calculate just how much energy and money is lost through a single dock door.

Here at Mestex we produce a number of “air curtain” products under brand names such as King, Applied Air, and LJ Wing.  All of our “air curtains” are intended for use on the large dock or ramp doors that you find in industrial or warehouse buildings.  The purpose of this little article, though, is to highlight the operating cost savings from using an “air curtain” rather than to tell you which one to use.  In order to do that we turned to one of our engineering analysis tools that we employ for more complicated application studies…Computational Fluid Dynamics, or “CFD”.

In some of our other blog articles we talked about CFD and how it works so I won’t go into that in detail but suffice to say that we can predict the temperature and airflow impact of HVAC equipment in a building…and do so with surprising accuracy.

For this study we created a model of a 20,000 square foot warehouse with a 20 foot height.  We then added a 14 foot wide by 16 foot tall dock door.  The model included R-13 wall construction and R-11 roof construction.  Our target inside design temperature in winter was set at 68 degrees F.  We threw in a few storage racks and a heating system on the opposite wall of the building from the dock door…about as far away as we could put it.  We then ran the CFD software with winter weather conditions from Syracuse, Chicago, and Atlanta.  (The little video above shows the airflow patterns in the warehouse and around the open door.)

Our CFD study showed a heating requirement of 3.5 million btuh in Syracuse without an “air curtain” and only 2.4 million btuh with an “air curtain”.  In Chicago it was 3.75 million versus 2.5 million, and in Atlanta it was 2.25 million versus 1.75 million.  You can see that the savings in btuh were significant in each case…even in Atlanta.

Converting this into dollars and cents translates into a savings of almost $21,000 per year in Syracuse, $19,000 dollars per year in Chicago, and $3,600 per year in Atlanta.  When you consider that a typical “air curtain” for a 14x16 dock door only costs about $18,000 completely installed and operational you can see why facility managers in cold climates can easily justify the investment…I mean, who doesn’t want a 1-year payback?  Even in “Hot-Lanta” the payback is 5 years just for heating…and the concept also helps with cooling.  We have also calculated the internal rate of return with various hours per day of door opening but that analysis is too lengthy for this already lengthy blog article.  If you want more information about the IRR or want information for your city just contact us at www.appliedair.com using the “contact us” selection under the “support” tab.

 

Shading and Make-Up for Building Designers

I just returned from a meeting in Florida and I was reminded of a couple of basic concepts that apply to virtually all building designs.

Our meeting room faced an outside wall with a couple of French doors to a nice patio area.  The weather was unusually cool for Florida and everyone sitting on that side of the table was able to experience that coolness first hand...even though the doors were closed.  During breaks the smokers in the group would gather on the patio and, again, in spite of closed doors the meeting room started to smell of cigarette smoke.

The problem, of course, was a lower pressure in the meeting room compared to the outdoors.  Somewhere in the conference center there was an exhaust system churning away without a counterbalancing make-up air system.  The only way that the exhaust system could satisfy its demand for air was to pull that air from outside the building, through the conference room, to its final point of exit.  Cold, smoke-laden air was drawn into the meeting room and occupant comfort was compromised.  Simply adding a make-up air system similar to the Applied Air DFL-series would have improved the indoor environment and cost very little extra to operate.  Remember that all of that cold air that was being sucked into the building caused the occupants to raise the thermostat set-point in order to compensate for being cold and forced the large main air handlers to operate for more hours than necessary.  Maintaining a positive pressure in buildings controls infiltration of smoke, dust, and un-tempered air and it is relatively simple to achieve.

The other basic concept that popped into my head is how important the building envelope is to controlling operating costs.  This particular resort was built many years ago but employed some pretty effective passive shading for the guest rooms.  My room had a wall of windows for natural light and a view but had a deep setback that prevented direct solar radiation.  This deep setback meant that the air conditioning system would see far fewer operating hours than an unprotected glass exposure would allow.  Since solar radiation is also a significant portion of the building cooling load the setbacks allowed a reduction in HVAC equipment size as well.

Building design has changed since the days when this hotel was built and deep setbacks are much less common.  But effective solar shading is still feasible through the use of external shades and louvers.  External shade technology has advanced to the point where it is possible for the shades to track the location of the sun and automatically provide continuous reduction in solar radiation.  Some external shading systems such as those developed by Colt Group actually contain photovoltaic cells that can reduce the building electrical demand by more than providing shading alone.

So two basic concepts for sustainable building design:  maintaining a positive indoor pressure to eliminate unwanted and untreated outside air from entering the occupied areas; and using modern external shading technology to reduce the solar load in the occupied areas which, in turn, reduces operating and capital costs.

Equilibrium

Equilibrium…we all try to achieve it in our lives.  An argument can go on forever if both sides maintain a high energy level and refuse to cool things down.  An argument can end when both sides take it down a notch and each reaches a happy place that they can both accept…a state of emotional equilibrium.

Odd as it may seem your air conditioning system is trying to do the same thing…reach a happy state of equilibrium…a balance between the high energy state and the low energy state.  Fortunately the system won’t get there under most circumstances because when the high and low energy states are equal then the unit stops providing cooling.

To simplify our thinking about this, substitute the word “temperature” for the word “energy”.  Now remember back to your days in physics class and remember that energy flows from a high state to a low state until the two states match and then the flow stops.  An air conditioning system takes advantage of that basic law of physics by absorbing the warm energy in a room and sending it to a lower energy place where the warmth is released and the cycle can start all over again.

One problem in this description of an air conditioning unit is that we usually don’t want the high energy released back into our rooms so we have to send that energy outside the room, or building, to get rid of it.  We do that by using refrigerants or water to transport the heat energy.  We also have to be sure that when we send it outside that it is at a higher energy level than the outdoors.  That is why we have compressors (and chillers which are just really big compressors) in our systems.  The compressors act as both a pump and as a device to actually add energy to the fluid that is pumped through the cooling coil in the room.  If you grab the side of a pipe entering a cooling coil it will feel relatively cold.  If you grab the pipe between the coil and the compressor it will feel a bit warmer.  If you grab the pipe on the leaving side of the compressor you might burn your hand.  The system has added enough energy to make sure that when the refrigerant or water reaches the outdoors it is at a higher energy state than the air outside the building.  That can be quite a challenge in a place like Phoenix or Dubai.

Most manufacturers realize that their equipment might be installed in those climates so they pick components in their systems that can operate under those circumstances.  But there are limits to what can be done.

The most widely available commercial cooling systems on the market are DX packaged units.  In order to satisfy the largest market (and sell the most equipment) these units are intended to be used for comfort cooling of people.  Since most people are “comfortable” when their office is around 75 degrees these units are designed around that operating point.  That is their happy point and that is the temperature of the air that is being returned to the cooling coil where heat energy can be absorbed into refrigerant or water and then sent outside to be removed.  The units will continue to operate at higher temperatures but remember that we need to be sure we send the heat outside at a higher level than the air outside. 

If you read the technical manuals for virtually every rooftop unit on the market you will see that, for a lot of really esoteric reasons, that rooftop unit is designed to operate at no more than 90 degrees returning to the cooling coil.  At that point the combination of components in the rooftop unit will be “maxed out” if the outside air temperature is in the 120 to 130 degree range. When the outside air temperature is 135 degrees on a roof in Phoenix then the high energy state and low energy state are so close together that almost no work is done and the temperature of the air coming out of the air conditioning unit starts to go up because the system is no longer rejecting much heat.  The system has quit working as intended and the situation usually spirals out of control as more heat builds up in the refrigerant or water.  Eventually so much heat has built up, and is compounded by the compressor, that the system shuts itself down to protect itself.

So, what does all this rambling have to do with anything?  Most of my blogs lately have been about mission critical/data center energy issues.  It is a big deal, and lots of folks are working on solutions, but economics sometimes trumps clear thinking or limits what can be achieved.

We are seeing more and more data centers specified with DX rooftop packaged units.  While these are normally high quality products they were originally designed to be at a happy place with, at most, 90 degree air being returned to the coil.  In a data center that is being designed to the latest ASHRAE standards the cold aisle can be anywhere between 80.6 and 113 degrees F.  When you allow a 20 degree F temperature rise across the servers before you return the air to the unit then I think you can see the problem.  The rooftop unit is being asked to operate well above its built in safety circuit limits.  Thus you end up with a self-limiting factor on how effective you can be in reducing the operating expense in the data center.  Even if you believe that your servers will be fine at 80.6 degrees F your HVAC unit probably will not be so fine.  And, to be honest, this same logic applies to CRAC units as they are nothing more than split DX systems.  So you have self-limited your options to cold aisle temperatures of no more than about 70 degrees F and your data center costs more to run than it could.

There is a class of rooftop unit that is better equipped to handle these situations and that class of equipment is commonly known as a DOAS, or Dedicated Outdoor Air System.  These systems, like our Applied Air FAP product, have been designed to expect Phoenix type temperatures across the cooling coil.  Returning hot aisle air at 105 or 110 degrees F is well within their “normal” operating ranges.  These systems are more expensive than a conventional rooftop packaged unit because of the components that are selected but they also provide the operating range that will allow the designer and operator to take advantage of the elevated temperatures that ASHRAE and the IT equipment people recommend for reducing data center operating expenses.

Mestex Hosts Independent Representatives at ASHRAE

Mestex Representatives Attend ASHRAE

With the annual ASHRAE/AHR meetings and exhibits in Dallas for the first time in 6 years, Mestex took advantage of the opportunity to host over 100 independent Mestex reps at the Mestex facility. We were also joined by a number of Mestek corporate employees including Stewart Reed, Mestek CEO.




Mestex DDC Dashboard

Test Area Demonstration

The reps were provided with guided factory tours that included presentations at four key areas in the plant...the gas-fired products test area, the hydronic products test area, the "Mestex Mall" show unit area, and the top secret Mestex R&D area. In addition to highlighting the extensive final test processes that every Mestex product endures the tour also highlighted the latest version of the Mestex DDC control system with full web-enabled interface and user "information dashboard".



"Dallas" Based Theme

Following the tours the reps gathered in the stage area that was set up in the plant for formal presentations on new software technologies that Mestex is introducing in 2013, a more detailed look at the DDC "dashboard", and a glimpse into a huge new sales opportunity. The presentations wrapped up with the introduction of the 2013 Sales Incentive program. The overall formal presentations were introduced by Mestex personnel who played the parts of characters from the TV series "Dallas".

Mestek Booth at ASHRAE/AHR Show

Over the following three days, Mestex personnel hosted a number of engineer and customer visits to the facility and also attended the ASHRAE/AHR show as part of the large Mestek contingent.

 

How We Used To Do It

I was recently reading an engineering magazine article (I know, I need to get a life) and came across a question that set me to thinking..."how did people stay cool before we had chillers?".  After all, in the grand scheme of life we have only had chillers and air conditioning systems for a very short time.  So what did people do before those things existed and what can we learn from that?

One of the first lessons from the past is that hot air rises.  Seems obvious doesn't it?  Believe it or not there is actually a company that is successfully convincing people that by making their air even hotter than everyone else they can do a better job of keeping people comfortable from 20 or 30 feet above them.  But that is a different story for another time.

Stack Effect

Because people realized that hot air rises, many early structures in very warm climates would be built with very high roof lines.  This would allow the hottest air to stay above the people and increase their comfort.  Many of those structures would also have vents or openings at the highest point of the roof so that the hot air could escape.  As that hot air left the structure it would be replaced by cooler outside air near the floor level.  A continuous circulation pattern would develop that kept the "cooling cycle" going.  The taller the structure, and the hotter the air, the faster this cycle would operate.  Today, we call that phenomenon "stack effect" and you see it in every tall building elevator shaft in the world.  You also see it in chimneys for residences.

After the invention of air conditioning though we seem to have forgotten one of the key elements of this natural cooling cycle...venting the hot air out of the building.  In most modern air conditioned buildings we keep the hottest air inside the building and just keep cooling it back down in a constant cycle that requires compressor or chiller energy.  In many cases the hot air inside the building is still cooler than the hot air outside the building so this might make sense during the hottest months of the year.  However, in the case of a data center or server room, the hot aisle air is usually much hotter than the air outside...but most data centers use cooling equipment that constantly tries to cool down that hot aisle air resulting in huge energy consumption.

Some systems also take advantage of the "stack effect" in a shorter building by recognizing that any heat source in the space will create it's own "mini stack effect".  Cooler air will be drawn towards the heat source and the hot air above the heat source can be exhausted.  This creates some natural circulation in the space and is one of the key principles behind "displacement ventilation".

Another lesson from the past is that evaporating water will make air cooler.  We actually use that very same principle in modern chiller systems that include a cooling tower.  The cooling tower is nothing more than a very large evaporative cooler.  In the old days people would use wet cloths or reeds in a window opening and when air entered the building through those wet items (probably accelerated by the building "stack effect") the entering air would get cooler and the people would be more comfortable.  Today there are many types and sizes of evaporative coolers available, such as those from Alton and Aztec divisions of Mestek, and they work even better than those primitive early methods.  But no compressor or chiller energy is required.

Of course there are building construction techniques that are also based on lessons from the past.  Positioning a building so that the smallest outside wall area is the one that sees the most sun will help keep the occupants cooler.  Using "thermal mass"...thick, heavy, walls...can also keep occupants cooler by storing cool night air energy in the wall and releasing it slowly during the hottest part of the day.  Again, we often build very light weight buildings today and try to compensate by adding insulation but nothing beats two feet of solid rock.  Some architects are working to revive this technique and research is continuing on using chemical treatments on walls and ceilings that allow them to store energy longer.  One case where creating a lot of "thermal mass" might not be such a good idea is in the data center world.  Depending upon how the hot aisle air is handled it might actually be a good idea to make the walls very thin so that the heat can escape to the outside through the walls.  Finally, the use of shades and window coverings is also a key lesson from the past.  Some companies, such as the American Warming division of Mestek, offer exterior solar shades that actually track the position of the sun and change angle in order to maximize the shading effect.

There are many other lessons from the past that could be discussed but the key is to stop and think about how we used to do things.  Sometimes adapting ideas from the past to ideas from today can result in the best overall solution.

Air Pollution and HVAC

Over the Christmas/New Years holiday break I was able to spend some time on the road crossing Texas, New Mexico, and parts of Arizona.  While I saw plenty of interesting sights it is not the goal of this blog to create a travel channel.  The goal is to highlight technologies and subjects of interest in the HVAC arena.

The subject that came to mind as I drove across these states was that of indoor air quality.  Two areas, in particular, raised my attention to this topic.  Phoenix, Arizona and El Paso, Texas were both covered with a thick layer of smog as I passed through those towns.  The climatic reasons are not all that relevant to this discussion but the "temperature inversions" that are common in those areas at certain times of the year mean that smog will develop and stay trapped for hours, if not days.  But those two cities are not alone.  Los Angeles, California has been well known for poor air quality for years.  New York City leaders have become concerned enough about outside air quality to include provisions in their new "Green Codes" that are intended to address the issue.  Finally, attention has been brought by the folks at NOAA to the fact that pollution in China eventually makes it way to the US on the jet stream.

HVAC products can either help mitigate this problem or simply move it from the outdoors to the indoors.  All buildings with occupants are required by building codes to have some amount of "ventilation air".  It has been common practice to introduce that ventilation air through conventional air handlers or packaged rooftop equipment.  In the vast majority of cases that equipment was designed, and is applied, with only the minimum level of air filtration included.  The primary goal of the filtration has been to protect the components of the equipment from dust fouling and to provide a nominal level of indoor air quality improvement.  New requirements and guidelines that specify MERV 11 and higher filtration are intended to let the equipment begin to mitigate the outdoor air quality before it enters the space.  But how effective is this?

In a conventional HVAC system design there will be dozens of these filters, if not hundreds, scattered all over the building in numerous air handlers or packaged units.  Maintaining all of these filters properly becomes an ongoing task.  In addition, if even better filtration is required, or desired, the average piece of HVAC equipment simply lacks the space to provide more filtration.

Dedicated Outdoor Air Systems, or "DOAS", equipment helps address this.  By isolating all of the ventilation air requirements into a single point, maintenance of the filtration system becomes much easier.  In addition, some "DOAS" equipment, such as the Applied Air FAP, is designed to allow multiple stages of filtration.  When combined with low airflow systems such as chilled beams the result can be very clean ventilation air even in areas such as those I drove through over the holidays.

As a final consideration for indoor air quality I would suggest that the old, ancient actually, technology of adiabatic or evaporative cooling might be considered.  Although adiabatic or evaporative cooling can provide effective temperature control in vast parts of the United States it can also provide an extremely effective filtering system as well.  Air is literally "washed" as it passes through the unit.  As part of an overall system where the adiabatic or evaporative cooling system, such as the Alton or Aztec products, only provides the ventilation air and other equipment handles sensible and latent cooling the improvement in indoor air quality could be dramatic.

Latency Intolerance

Several things occurred almost simultaneously over the last week or so that spurred my thinking for this latest blog post.

The diagram at the right illustrates the network configuration for our DDC control system called Adaptaire.  We have launched a project to add some additional functionality to the software that has been around for almost 12 years now.  The function that we are adding is a real time "dashboard" that will give the building occupant feedback on how well the system is performing.  Because the "dashboard" is displaying information in real time, and might be transmitting that data over the Internet, one of the factors that we need to consider is the speed at which we "refresh" the data.

The second thing that spurred our thinking is our plan to migrate our current product selection software from a desktop environment to a web-based environment.  This means that the data entered and the answers received back from the selection software will be transmitted via the Internet.  Experiments with some very early versions of the software have highlighted "speed of response" issues that must be addressed as we move forward.

The third event that provoked this blog entry was a meeting with one of the chief design engineers for Integrated Design Group, a data center design firm responsible for projects worldwide.  In the course of the discussion this engineer made a prediction that the data center industry will move to more, and smaller, data centers.

The common thread in all of these items is the "need for speed" and that translates into reducing something called "latency".  "Latency" is the time it takes for your input, or our dashboard refresh signal, to actually reach its final destination.  As incredible as it might seem, even though these signals are moving down fiber-optic cables at the speed of light, it can take a "long" time for that signal to reach its end point.  First, remember that "long" in this industry is measured in nanoseconds.  Second, remember that most of the signals that are transmitted are actually transmitted at least twice because of error checking.  In addition, most of the time those signals pass through several routers and servers before reaching their destination and each of those "hops" also includes error checking and traffic control delays.

One solution, and the reason this engineer believes the future of the industry is more, and smaller, data centers is to locate the data centers as close as possible to the source of the signal or destination of the signal. This will reduce the number of "hops" and also reduce the physical distance between points...thus reducing "latency".

The "latency" issue is so important in industries like equity trading that data center companies are battling each other to locate their facility just one block closer to the Wall Street trading floor.

We are all becoming spoiled by the speed at which we can find information via the Internet, download music, watch on-line videos, etc....but the end result is that we are acquiring a new "disease" that I am calling "Latency Intolerance".