Category Archives: HVAC Calculations

These posts discuss different HVAC calculations like fan power and energy, sensible load, etc.

Creating a Third Axis In Excel

One of the challenges that came up when I was creating the time series graph of a 9,000 ton chiller plant load profile that I show in my previous post was that I wanted to plot data series that had … Continue reading

Posted in Data Logging, Excel Techniques, HVAC Calculations | Leave a comment

A New Application for Plot Digitizer (Plus a Quick Look at Hydraulic Variable Speed Drives and Chiller Free Cooling Cycles)

Those of you who know me know I am quite enamored with a little freeware application called Plot Digitizer.  If you are unfamiliar with it, the application allows to to create CSV (Comma Separated Value) files from the lines in … Continue reading

Posted in Boilers, Hot Water Systems, and Steam Systems, Chillers and Chilled Water Systems, Data Logging, Excel Techniques, HVAC Calculations, Motors, Operations and Maintenance | Leave a comment

Exploring Evaporative Cooling–Part 1

If you look at a psych chart closely, you will notice that the constant wet bulb lines are not exactly parallel to the constant enthalpy lines. Note that to make things more visually apparent in this blog post, for most … Continue reading

Posted in Air Handling Systems, HVAC Calculations, HVAC Fundamentals, Psychrometrics | Leave a comment

Resources for the Resourceful – Utility Analysis Spreadsheet Tool

Authors Note: Since the point in time when I published this post, some of the links have expired. So, I have gone through it and renewed them and also made a few edits. Linking to the Weather Data Depot in … Continue reading

Posted in Excel Techniques, HVAC Calculations, Operations and Maintenance, Resource List and other Resources, Retrocommissioning Findings | Leave a comment

Site versus Source Energy

Author’s Note:  I originally posted this in September of 2007 and used a report I had found at that time to develop some of the source energy factors I used in my illustration.   Since then, I have found a number … Continue reading

Posted in HVAC Calculations, HVAC Fundamentals, Resource List and other Resources | 2 Comments

Build Your Own Psych Chart – Creating the Data for the Saturation Curve and a Bit About VLOOKUP

So here I am, over a year later after starting this string, getting back to it.  All I can say is life happens and sometimes, because of that, you find that what you set out to do takes a bit … Continue reading

Posted in Excel Techniques, HVAC Calculations, HVAC Fundamentals, Psychrometrics | Leave a comment

A Free Electronic Psych Chart and How to Use It to Plot Basic HVAC Processes

Ryan Stroupe of the Pacific Energy Center recently worked out a deal that allows him to provide a free limited capability version of Hands Down Software’s electronic psych chart.  You can get a copy at this link and a overview … Continue reading

Posted in Air Handling Systems, Economizers, Excel Techniques, HVAC Calculations, HVAC Fundamentals, Psychrometrics, Resource List and other Resources, Weather and Climate Interactions with Buildings and Systems | 1 Comment