Schedules getting slimmer
I just read (Rebecca Ellis’s) article in the May 2013 issue of Engineered Systems magazine (“The Importance of MEP Coordination”). Thank you so much for telling it like it is when it comes to CMGC’s only wanting to refer back to their schedule and expecting that all shall be done by that date, no questions or comments allowed.
I’ve been in the building automation industry since electronic controllers gave way to DDC, and I have been commenting for many years now about how job schedules keep getting more and more compressed. Certainly, it’s understandable that an investor wants a quick turn around on their money, and competition among contractors is always going to promote promises for more, faster, and less expensive. That’s free enterprise, right? I love this country!
Just wanted to thank you for being the bold one to put it in print and expose the plight of us subcontractors who are continually pressured to produce more in less time while attempting to maintain the same quality of product. Really, I do prefer to have my jobs checked out in-house before the commissioning agent starts writing their punch list.
Thanks again. Much appreciated!
Quality Control Manager
Thank you for taking the time to write this email, Mr. Nickles. I’m not sure we’re going to change the world, but I don’t want to leave behind the notion that I was willingly complicit in the way things have evolved (devolved?) over the past 25 years.
Wasting energy efficiently
The June 2013 Engineered Systems article, “Condensing Boilers: Maximizing Benefits” does not provide any cautions about using the authors’ recommendations for outdoor temperature reset of hot water, and especially with condensing boilers.
First, outdoor temperature reset should not be used in intermittently occupied buildings, such as schools, office buildings, and religious buildings. When these buildings are not occupied in winter, and room temperatures are set back, often as required by codes, the mass of the building and its contents falls below the occupied room temperatures. When occupancy is restored, and heating is started, especially at warmer outdoor temperatures, the hot water temperatures are not high enough to restore comfort conditions in a reasonable time.
For example, when outdoor temperatures go below freezing on a weekend, and then go up to the 50s and 60s on a Monday morning, the hot water supply temperature with outdoor reset will not be sufficiently high to raise room temperatures to the desired setpoints. In addition to offsetting the heat loss, it is necessary to have sufficient additional heating capacity to raise the temperature of the building mass and its contents. This is also why ASHRAE Standard 90.1 provides an explicit exception to the requirement for setback controls for “Radiant floor and ceiling heating systems” because of the mass of these building systems.
Second, the statements by the authors that the amount of heat required is proportional to the outdoor temperature are not valid in most commercial buildings due to internal heat gains. These internal heat gains make these buildings self-heating to at least some degree. Thus, the internal heat gains can provide sufficient heat down to some lower outdoor temperature before heat is required from the heating system, and they are often variable.
For example, school classrooms often have enough heat generated by the lights, equipment, and occupants during occupancy to maintain room temperature setpoints when the outdoor temperature goes down towards freezing. This invalidates the authors’ theory that hot water supply temperature should have a linear relationship to outdoor temperature.
Third, with the substantial reductions in building heat loss in recent years, the corresponding reductions in boiler capacity, and the desire to limit boiler capacity to the building heat loss, there is no boiler capacity available for morning warm-up or morning pickup. The result is that building operators in intermittently occupied buildings keep them heated around the clock to avoid comfort complaints on cold mornings. Thus, too many efficient buildings end up wasting energy efficiently.
Larry Spielvogel, P.E., FASHRAE
Bala Cynwyd, PA
Whither the website?
Howard McKew — Yours is my favorite monthly column when I receive my ES. We purchased some of your Practitioner’s Guides over the years. It provides great insight about the business and industry.
I was unable to locate your website of “Building Smart Software” recently. Would you let me know if your website is down or if you moved to a new website?
Energy Performance Engineering, LLC
Thank you for your email, and I’m glad you enjoy my columns.
I have taken my website down because I’m semi-retired and I’m fortunate enough to be selective with the work I do so I don’t want to be “too busy” and the website would bring work to me that I preferred not to do at this point in my career.
I also removed the website because I didn’t want to update the Cx-3 software to Windows 8 and Microsoft 2012. Each time I did an upgrade, to continue to use Microsoft as the platform for my own software, it costs a lot of money and at this time I don’t care to keep pace with Microsoft.
If there is something in particular I can help you with relative to what I was offering on my website, please let me know and we can talk. Thanks again for your email and comments.