Enthalpy is defined as the amount of internal energy within a system combined with the product of its pressure and volume. When dealing with the term in the HVAC industry, we usually assume that the process is at a constant pressure and, as such, the change in enthalpy is equal to the heat absorbed or released. At its core, the main function of an HVAC system is to transfer heat, which is a form of energy. The first law of thermodynamics, the Law of Conservation of Energy, tells us that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another. From that, we can infer that the only way to cool a space down is to remove the heat energy and transfer it somewhere else, typically outdoors. This is generally accomplished by absorbing heat from an airstream and then distributing this cool air to the area we wish to control; it helps to think of conditioned air like a sponge with the capacity to ‘soak up’ heat. The air, now laden with unwanted heat, is routed back via a Return Air pathway to start the process over again. The newly absorbed heat is ‘wrung out’ and expelled, and the cool air is distributed again in a constant cycle. This ‘wringing out’ process is mainly accomplished by mechanical cooling, such as a compressor, or free cooling provided by an air-side economizer.Continue reading Enthalpy as it relates to free cooling in HVAC
The Energy Cost Index (ECI) is the measurement of cost per square foot per year of conditioned space in a facility ($/ft²/year). The average ECI of electricity for an office building in the U.S. is about $1.73/ft²/yr according to the U.S. Energy Information Administration. What are you doing to reduce your ECI?Continue reading 5 Energy Conservation Measures with Quick Returns
Rather early in my career, I began working with destination dispatch elevator systems and have since had the opportunity to be engaged with a handful of these projects. Although I am far from an elevator expert, a fair number of my days as a technician were spent working on access control systems which are frequently correlated with destination dispatch.
As I’m sure you know, power companies charge a premium when a certain demand threshold is reached. Load shedding during high electrical demand periods is a good way to lower electrical consumption and avoid paying premium prices for exceeding peak demand limits. Metering or monitoring the load for the building will tell you when that threshold is nearing.
Load shedding will probably not work if the demand follows a bell curve during the day, where the threshold is exceeded for a good portion of the day. In this case, the building needs to find ways of increasing energy efficiency, either by purchasing more efficient equipment, eliminating waste, etc. However, if there is a peak in the demand curve that is exceeded around the same time everyday, load shedding could help. The question is, what can you afford to shut down without making people uncomfortable and angry? Continue reading Load Shedding and One Approach in CBAS
On March 21, 2018, Computrols Director of Research and Development, Mike Donlon, presented on the topic of “Optimal Virtual Metering In Building Automation” at the Globalcon Conference in Boston, MA. The below information is a transcribed excerpt from his session.
Continue reading Optimal Virtual Metering In Building Automation
The CBAS Web product was originally introduced so that tenants could schedule their own overtime air and lights while making it easy for building management to bill them these services. This is still true and it’s really easy to set up. This feature saves money because you don’t have to pay someone to take calls and enter the tenant’s overtime requests into CBAS. Management can now also setup tenants to handle their own access control cards, but let’s talk about overtime tenant billing for now. Continue reading George’s CBAS Tips, August 2018
The Importance of the Probe in BACnet
When setting up 485 communication to a BACnet device like an AHU, it is important that you Probe it. This gets you some important information:
- Instance number is a good thing because if you add it to the program screen of the controller, it connects much faster when CBAS is restarted. Instance is usually provided in the Probe file but can sometimes have a different name.
- A Probe gets you the list of points that are on the AHU controller. Then you can add them from the Probe file easily by clicking the controller then click Add Points From Probe File.
- Perhaps the most important advantage to probing is that it automatically sets a few parameters to be used by CBAS that can improve performance. Note that you can alternatively set these parameters manually.if probing isn’t possible The most useful of these settings are are COV and Read Multiple. COV is Change of Value and if it is available, it sends any changes in value to the host. Read Multiple reads up to 14 points at a time. By default, CBAS only reads one point at a time unless you have Read Multiple set.
The building automation industry is growing, and the trend doesn’t appear to be changing any time soon. According to research by IHS Technology via this Buildings.com article, the market for building automation equipment is projected to grow by more than 40% over the next five years.
If you are familiar with the industry, you are likely aware of the talent and knowledge gap between the seasoned veterans and industry newcomers. With many building engineers, system engineers, and controls specialists approaching retirement, there is a need for fresh talent in the industry. While fresh talent and enthusiasm are certainly needed, how is the knowledge gap being addressed? Continue reading Where to Get a Building Automation Degree
As a part of our services, Computrols offers 24/7 phone support to all of our customers. If you have ever taken advantage of this offering, you have likely spoken to our Technical Support Manager, George Hingle. George has been employed by Computrols for over 15 years and is one of our most knowledgeable team members when it comes to troubleshooting in CBAS. As a means of building on our already robust FAQ page, George has agreed to share some common issues he sees in our newsletter each month. Continue reading George’s CBAS Tips, April 2018
In the January/February 2008 edition of Facilities Manager Magazine, there was a featured article titled, “Pay Now or Pay Forever: The Design of Control System Software”. This article was recently brought to our attention by one of the original author’s LinkedIn posts which outlined the fact that not much has changed in the BAS industry over the last 10 years. At Computrols, we couldn’t agree more. Below, you will find some of the most profound quotes from this article and Computrols’ approach to remedying these issues. Continue reading Investing in a Building Automation System