Thursday, May 3, 2018

Specifying Control Logic

The controls on VAV boxes have changed quite a bit since their conversion from pneumatic in the early 80’s. Back then, we often referred to overly complex control sequences as ‘Klingon Spaceship controls.’ One would think when DDC controls arrived, that things would be much simpler. Of course, this isn’t what happened.

Instead, we got a proverbial ‘black box’ with “Trust me” written on its side in disappearing ink. Simply broken down, there are two types of controls for VAV boxes, line and block. A line controller is essentially a programmable device with its code written in a ‘line-by-line’ manner. A block controller’s code is written in pre-programmed blocks that work together, hopefully. Technically a ‘line-by-line’ program is broken into functional blocks too. So the question is: What functions are the blocks performing?

It’s difficult to get control suppliers to program controls to do what we expect them to do. We (Krueger) have discussed it a lot with Specifying Engineers and some of our reps. There is a lot of ‘push-back’ from control contractors who want to reuse what they can, and charge the maximum amount for inventing what they feel are new, ‘custom’ sequences. Specifying engineers have told us that they feel the control contractors really don’t understand what the specified products can or should do.

ASHRAE Guideline 36: High Performance Sequences of Operation for HVAC Systems is going to be available this June, and it should provide a basis for writing specifications for VAV systems. I’ll be cutting and pasting from this document to try to put together a guide controls specification for a VAV Series fan box with a sensible cooling coil. Stay tuned for updates!

Authored by: Dan Int-Hout, Chief Engineer Krueger

Friday, April 13, 2018

What A Long Strange Trip It Has Been

As we train new employees and I look ahead to eventually winding down my career, I tend to look back over my 40+ years in the Air Distribution field. I can say the journey has been, to say the least, interesting. 

I started my adventure in HVAC after a tour in the Air Force. I ended up back in the town in Central Ohio, where I went to school (Denison U in Granville, Ohio), with a degree in Biology. I was hired as a “Scientist” in a product testing lab by Owens Corning Fiberglass at their research center there. I got involved in an air distribution problem and joined ASHRAE to learn more about the technology of air distribution. That began my journey in air distribution research, standards and building codes, which continues to this day. I chaired the ASHRAE thermal comfort standard committee (Standard 55), the comfort and air distribution technical committees (one of them twice), as well as several other related technical committees. I even got involved in Acoustics, managing the development of an Acoustical Application committee in AHRI. I was involved in different capacities with the ventilation standard 62.1, and I’m still the air distribution consultant to that committee. I have since become both an ASHRAE Fellow and a Life Member. I even spent three years as a Director at Large of the society, likely the first degreed Biologist to do so.

One of the advantages (some would say disadvantage) of having been around as long as I have is the ability to sometimes see where all this is headed. I was asked by a customer several years ago what I thought would be the “next big thing”. I predicted that someday there would be a requirement to deliver (measured) ventilation air directly into every occupied space. The new Washington State commercial building code requires just that. 

Having been involved in the development of VAV from its crude beginnings in the early 70’s, I watched the progression from pressure-dependent to pressure-independent flow control. I also experienced the transition from pneumatic to digital controls. Does anyone still remember how to set pneumatic velocity controllers? What is apparent to me is that we are going through a similar progression with ventilated air. We are still working to get the control sequences we need to be implemented in DDC controllers.

VAV boxes went from system powered and constant volume induction types to parallel fan powered units, then series fan powered units. The ECM motor, introduced 20 years ago (really, 20 years ago?) is now required by code in many jurisdictions, and analog outputs on DDC controls allow fans to vary airflow. This results in variable volume series flow terminal units. We are challenged today with getting controls to properly manage this exciting technology.

Back in 1973, it was difficult to measure low air speeds. The required anemometer was found to have an accuracy of +/- 50 fpm at 50 fpm! I attempted to verify a GSA specification of 20 fpm minimum air speed with this crude device. Working with an anemometer manufacturer, we developed the omni directional anemometer as well as ASHRAE Standard 113, which defined a repeatable method of test for its use. Eventually, we developed methods of predicting air distribution performance using techniques established by a research project conducted by ASHRAE (Then ASHVE) at Kansas State University in the 60’s. The KSU research was validated at today’s lower air flows in a subsequent research project at the University of Texas at Austin in 2013. The premise that “there is no minimum air speed for comfort” (included in the first release of ASHRAE Standard 55 in 1979), was finally validated in a research project that took place in a million square foot building in 2012. Sometimes these things take a while.

While visiting California and Arizona last year, I was promoting the concept of using a variable volume series fan box, (and a sensible cooling coil), to deliver a measured quantity of ventilation air, as well as efficient and flexible operation of economizer (both air side and water side) to commercial spaces. This concept has been in use in Washington DC (starting with the Pentagon) for 16 years. Imagine a concept starting on the east coast and spreading west (instead of the other way around). Operating a series fan box at the lowest possible airflow, while meeting demands, can provide a comfortable environment as well as an energy efficient solution. The energy consumption of ECM boxes has been documented through joint ASHRAE / AHRI research at Texas A&M University. That data is being added to HAP TRACE Energy Plus and other energy use computer programs. Three published ASHRAE journal articles describe the research and its implications.

I am proud to have been involved in all aspects of this technological development. Starting with an impossible specification in a GSA building in 1973, we in the air distribution industry have finally figured out how to effectively and efficiently manage indoor environments in a measurable and controllable fashion. Using ADPI prediction techniques developed in the late 60’s, and validated in the last few years, we can provide design guidance for engineers to lay out air distribution in a way that will ensure occupant comfort at today’s low interior loads, taking advantage of the latest DDC controls and variable fan speed technology. I look forward to assisting the newcomers to this industry as we take the technology into the future.

Authored by: Dan Int-Hout, Chief Engineer Krueger

Tuesday, August 1, 2017

My Time on the ASHRAE Board

As many of you know, I served for the last three years on the ASHRAE Board as a Director at Large. It was a three-year term, which ended at the June meeting in Las Vegas. It was certainly an interesting time... I served as ExO (Executive Officer) of two committees: RAC (Research Administration Committee) and the newly formed RBC (Residential Building Committee). As ExO, my function was to ensure that the committees ran well, that membership and leadership functioned properly, and that issues were brought to the Board (through Tech Council, on which I also served).

During this time, ASHRAE established a European Region. This not only helped build alliances with other international organizations, but it gave me an opportunity to spend time with a number of people that I would not have otherwise. And to make it that much more enjoyable, I was also able to continue working alongside others that I've known for years. So, it's no surprise that I was a bit sad to see it come to an end.

Since then, I volunteered for and have been accepted as a voting member on the RBC, where I was previously an ExO. The RBC has been tasked with getting ASHRAE involved in the residential side of our industry, which has received little attention thus far. The overlap between commercial and industrial engineering with residential starts with multi-family dwellings. As such, one of our first orders of business was to develop a multi-family design guide; it should be going to bid soon.

ASHRAE is a rarity in technical societies. It brings together engineers, scholars, and manufacturers for the purpose of researching and developing true consensus standards for the industry. I am proud to have served on the Board and will continue to support ASHRAE in the future.

Authored by: Dan Int-Hout, Chief Engineer Krueger

Thursday, May 25, 2017

High Performance Air Systems

Almost a year ago I wrote a blog about the new code in Washington State. AMCA objected to the wording of the code through several avenues, and was essentially ignored. As I said then, the code mandates “the use of decentralized ventilation systems using dedicated outdoor air systems (DOAS) to deliver 100 percent outside air independent of heating and cooling systems.” This code, in effect, prohibits central station air handlers.

It seems reasonable to assume that the authors of the code were heavily influenced by proponents of “non-ducted” systems, including VRF, WSHP, and Chilled Beams. All these systems require that outside air be carried through ducts to every space, so “non-ducted” is a pretty poor definition.

AMCA had already formed an ad-hoc committee on “High Performance Air Systems”, issuing a white paper this past January. I presented an HPAS webinar on May 4 (2017) to discuss this white paper and an article in HPAC “Specifications for High-Efficiency VAV Systems,” which outlines the requirements and exceptions to the code. The two documents spell out the advantages of “ducted” systems as well as the disadvantages of the other types. Earlier in 2014, I presented a two part HPAS webinar before the Washington code was in place. Both recorded webinars are available on the Krueger website.

I’m a bit surprised that this isn’t front page news. I am more surprised that after visiting engineers in Phoenix, Rochester, Saskatchewan, and Sacramento, there was no awareness of this code change. I have been predicting that one day we would see a code requiring direct measurement and control of ventilation air into all spaces --- and here it is. As it turns out, the “chilled box” I have been touting for the past few years meets most of the requirements of the identified alternates in the Washington State code. As you might guess, I mentioned this in the webinar!

Authored by: Dan Int-Hout, Chief Engineer Krueger

Wednesday, April 5, 2017

A Look Back

I’ll be doing another ASHRAE talk, this time in in Sacramento, CA. As I prepared for this trip, I started to think back to when I lived there for a year right out of college, going to the USAF Navigator School at the (now closed) Mather Air Force Base, which is about a mile from where I’ll be giving my talk. What I couldn’t believe is that it has been 50 years!

I served 5 years in the USAF, separating in 1972. A year later, I entered the building construction industry, working for Owens Corning Fiberglass (OCF) in their Product Testing Laboratory, in the same Ohio town where I went to college. Within a year, I reopened their Air Lab to study an issue with a specification on room air motion. It was then that I became involved in ASHRAE and the Air Diffusion Council to better understand air distribution, thermal comfort, and applicable standards.

At OCF, for any claim we published or advertised, we were required to have actual supporting test data (conducted in accordance with established test methods). I have carried that “rule” with me ever since, for 44+ years.

At Krueger, we have a set of folders on the server that hold performance data for every VAV terminal unit and air device for all our printed and electronic catalogs, dating back to 1983, when Excel became available on computers running MS-DOS. We learned in the early 80’s that it was not possible to develop an electronic catalog from printed data. Rather, what we found was that the printed data needed to be produced from the same equations and data used to create an electronic catalog. Krueger’s KEC (Krueger Electronic Catalog) was released in 1984 in MS-DOS. It is still able to run, be it painfully, as it doesn’t use a mouse or function keys (neither of which had been invented yet).

As I train new Krueger employees in the art of data gathering, regression, and catalog preparation (printed and electronic), I hope to instill the spirit of traceable and verifiable performance data that I learned all those many years ago.     

Authored by: Dan Int-Hout, Chief Engineer Krueger

Thursday, March 30, 2017

Getting Caught Up

Well, it's March of 2017 and I haven’t posted a blog in 6 months. I guess it’s time.

I last posted a summary of the ASHRAE Journal articles I have had published way back in 2015.

- June 2013 - Slots are Adjustable
- July 2013 - Comfort vs. Energy
- August 2013 - VAV Research Validates Low Airflow Comfort
- September 2013 - Balancing Factors
- October 2013 - You Have to Prove It
- December 2013 - Hospital Operating Room Air Distribution
- January 2014 - Reheat Coil Issues and Answers
- February 2014 - High Bay Air Distribution
- March 2014 - High Performance Air Distribution Systems
- April 2014 - Compliance to Standard 55 (Comfort)
- May 2014 - The Deal about Duct Lining
- August 2014 - The VAV DOAS Fan Powered Terminal
- November 2104 - Proper Selection of Chilled Beams  
- January 2015 - Variable Volume Series Fan Box

Since then, I have had three more published, two in the Journal and the final one in the on-line version of the Journal.

- July 2015 - Basics of Air Distribution - This article provided a basic understanding of how well mixed air distribution works in a space.

- October 2015 - History of Fan Powered VAV Terminal Units - Co-authored with another industry colleague, this article traced the history of the fan powered terminal unit in commercial office systems.

- October 2016 - Part of Making Connections - In this, I described how three technical paths, all starting in the 70’s, progressed to finally come together in 2016 to allow new designs to be employed for improvement in acoustics, energy, and comfort.

Planned for this summer are three ASHRAE Journal papers. They will summarize a significant amount of information gained from a study of series and parallel fan powered terminal units performed by ASHRAE and AHRI. These will be co-authored with other industry colleagues.

Authored by: Dan Int-Hout, Chief Engineer Krueger

Monday, July 25, 2016

NW Code Requirements

The State of Washington has issued a new building code that affects, among other spaces, office buildings. The code is very specific about ventilation and building energy use in that it mandates “the use of decentralized ventilation systems using dedicated outdoor air systems (DOAS) to deliver 100 percent outside air independent of heating and cooling systems”.

What this means is that DOAS systems are mandated and that conventional VAV systems, which mix ventilation and return air at an air handler, are essentially prohibited. While there is an exemption for “High Performance VAV systems”, which I have described in an ASHRAE Journal article and in earlier blogs, it tends to favor those that are disconnected from the ventilation supply, such as VRV and chilled beams.

What is particularly interesting is the requirement that states “ECM motors that vary with load are required for all fan powered VAV terminal units”. This, of course, is what I have been advocating for some time – variable volume series fan box control. When employed with 100% outside air through the VAV inlet (and a sensible cooling coil on the induction port), all the requirements of the new Washington code are met. I’m willing to bet that this will not be the only such code requirement that we’ll see in the future.

Authored by: Dan Int-Hout, Chief Engineer Krueger