Engineered Systems - October 2008 - (Page 9)

Letters cal separation, I can say our data hall probably wouldn’t have worked with this hot alley approach because the heat just built up too much trying to cross 100 ft of open hall. But all of this is conjecture without a CFD. I would say that anything you could do to provide separation while minimizing infrastructure is a plus. Ceilings cost money, so if you come up with design that doesn’t need one, that’s a good thing. If you see things differently or if you have a design without a ceiling that worked (with similar Watt density of course) let me know. I’m always willing to learn a new trick. control in the labs (many fume hoods). We had night setback and found we saved 90% of what a VAV system would, without the headaches and initial cost. 2. I now have a project in Tucson, AZ, where I am building an 110,350-sq-ft pharmaceutical R&D lab/office facility. It is the same 70%/30% ratio for lab/office. We have two 600-ton York centrifugal chillers, which works out to 92 sq ft/ton. Yikes! This is with a VAV control system and chilled beams. I am wondering if your rule of thumb 320 sq ft/ton works in Arizona? Lab requirements I really enjoy Howard McKew’s “Tomorrow’s Environment” column in Engineered Systems. Amanda McKew’s “HVACR Designer Tips” column is great also. I have a couple of questions. 1. Howard’s column on sq ft/ton really got me thinking (“Going In The Wrong Direction,” April 2008, page 78). I built a 1.1 million-sq-ft pharmaceutical research lab/office complex back in the early ’90s. The lab/office ratio, in sq ft, was 70%/30%. We had an installed chiller capacity of 6,000 tons, which works out to 183 sq ft/ton, with constant volume John G. Cocco, P.E. Senior Manager, Project Engineering sanofi-aventis Bridgewater, NJ McKew responds: It is a discouraging situation as I see more and more design engineers overdesigning for various reasons, none of which (I believe) have anything to do with good engineering practice. I guess the feeling “bigger is better” continues to exist with design engineers. I am striving to change this approach with what I call responsible documents, but see the ones who will embrace this will be the contractors who are gearing up with more and more in-house engineering resources and are willing to take ownership for what they build. 1. Have you looked into retrocommissioning based on how things are actually operating today? There can be some significant savings when you have 20/20 hindsight of design-to-actual. We are seeing more of this as energy prices climb. 2. While you have higher drybulb temperatures, your wetbulb temperatures are much lower, as well as winter conditions. I’d have to look at this but I’d say you should still be much higher and in line with my 320 sq ft/ton. The killer for us is wetbulb, and you don’t have that. I obviously don’t know what your design engineers have taken into account, but it is probably very conservative. I now have a project in Tucson, AZ, where I am building an 110,350-sq-ft pharmaceutical R&D lab/ office facility. It is the same 70%/30% ratio for lab/ office. We have two 600-ton York centrifugal chillers, which works out to 92 sq ft/ton. Yikes! This is with a VAV control system and chilled beams. I am wondering if your rule of thumb of 320 sq ft/ton works in Arizona? — John G. Cocco, R.E. Bridgewater, NJ Duct Smoke Detector Won’t Fit? Input 217 at www.esmagazine.com/instantproductinfo w w w. esmag a zi n e . c o m ESM10084SSAd1.indd 1 9 9/15/08 11:56:48 AM http://www.nxtbook.com/nxtbooks/bnp/es_200804/index.php?startid=78 http://www.nxtbook.com/nxtbooks/bnp/es_200804/index.php?startid=78 http://www.esmagazine.com/instantproductinfo http://www.esmagazine.com

Table of Contents Feed for the Digital Edition of Engineered Systems - October 2008

Engineered Systems - October 2008 Contents Editor’s Note Letters Back2Basics HVAC Challenge Case in Point Commissioning Building Automation HydroTech HVACR Designer Tips Special Insert: Engineer's Technical Library Fall 2008 Living Wild! Chilled Beams in Chicago Phoenix Convention Center: On The Rise Cold-Climate HVAC Challenges Humidification Strategies For Data Centers & Network Rooms Special Advertising Supplement: Tabb Talk Computers & Software Issues & Events Products Literature & Catalogs Glossary Classifieds Advertiser Index Tomorrow’s Environment

Engineered Systems - October 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.