" I was able to save a lot of my time in ductwork estimating by using your spreadsheet.  Thank you HVACnotebook for htis great spreadsheet.  Wish I had it years ago."

                                                         Steve P. , February 2019

" This is so easy that anyone can do these energy analysis using these spreadsheets."

                                                      Dave, June 2017

" My team and I use this spreadsheet almost every day.  It has many useful calculatoins.  HVACnotebook was even able to customize it for us to include our own calculations."

                                                     Thomas M. , May 2018

" I use this spreadsheet to keep track of my customers and clients.  It's so easy to use.  I didn't know Excel can do such thing before."

                                                   Frankie C. ,July 2017

" This is a great spreadsheet.  Now everyone in my office use it to do piping estimate which makes it easier for me to check or take over."

                                                      Sam C. , Janurary 2016