Although energy-savings programs have been around for a while, the need for energy-savings data continues to grow as energy costs continue to rise. The North America Motion Controls Division of Danfoss has been working to develop a means to supply accurate data on energy consumption of AC drives and motors.

The software program - Danfoss Graham HVAC Energy Analysis for VLT Series Drives - estimates electrical energy consumption and a simple payback for fan and pump applications that use an AC drive and motor. The software allows the user to select a conventional system and compare it against an AC drive system.

The program was released in late 2004, but it had its roots a lot earlier than that. "I wrote this program in DOS about 15 or 20 years ago," said Ken Fonstad, Danfoss training manager.

Mark Hansen, Danfoss director of business development, said that his company designed the program because its customers want to know the payback cycle of various variable-frequency drive (VFD) motors. "Customers use VFDs in a lot of different applications, and they want to know how soon of a payback they'll get with their energy savings," he said. "Since VFDs are a major component of an HVAC system, it has been very beneficial to have a payback analysis."

He said that most of the major HVAC equipment manufacturers have some type of energy analysis program designed to help customers find better energy solutions in the face of rising energy costs.


Up until now the HVAC Energy Analysis program has been used as a means of showing customers the potential energy savings of a system using VFD drives. "The program as it exists today is a type of presale, allowing the customers to see what the projected energy savings will be," noted Hansen.

The current scenario is the customer applying the VFD to their system and needing data to support their decision. Danfoss would calculate the costs to install the drives and operate the system based on current energy costs and at the end of a designated time period, the customer would be able to ask, "Did the VFDs do what you said they would do?"

A new use for the program will occur sometime around July, when Danfoss will introduce its VLT Series HVAC VFDs. This new line will allow for monitoring through a USB port on the drive.

"The program will be able to communicate directly with the drive and download a profile of the building," said Hansen. "You can run the program on a laptop, even two years later, and get an energy profile of a building.

"The program, when used with the new drives, will allow us to do a post-analysis of how the VFDs have performed."

Fonstad said the program has a nice balance between basic information and more advanced information. "If you just need a basic calculation you can ignore the advanced features and still get a very accurate calculation," he said. "This is done to satisfy the high-tech people and those who need to crank out a quick answer."

The program takes into account the system curve rather than just the fan or pump curve. "Most programs I have seen don't offer this feature and don't accurately model the system," Fonstad said. "The goal is to get the most accurate results."

He also talked about the importance of analysis based on all of the costs and operating data that go into an HVAC system. These factors can be seen on the startup screen in a seven-step process, which include:

1. Customer information

2. System data

3. Select comparison system

4. Initial and annual costs

5. Energy calculations

6. Energy savings

7. Save, print, e-mail or export analysis report.

"We've had a lot of success with the product and have a couple of major OEM customers who have used the program on a consistent basis," said Hansen. "The product allows us to presale and to troubleshoot the system for our customer on the back end."

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Publication date: 04/10/2006