by Professor Gene Wengert
We are currently proposing our insulating system "ASTEC" to a company building two wood kilns of the following dimensions: 35ftx200x100. In order to provide a complete proposal to our client we are trying to produce a pay-back period report using our system as opposed to other systems in the energy savings per year.
It would be very helpful if you could provide us with detailed information about the process as well as the energy needed in this process.
Your questions are really more appropriate for a consultant who can work with you to develop the precise data you require. In brief, the energy required to dry lumber is about 3 to 5 million BTU per MBF. The lower number is for air dried; the higher for greener material. About 20% of this energy is lost through the walls, floor (quite a bit), and roof.
Some years ago I figured the benefit of using 6 inches of insulation versus 3 inches in a kiln wall and we saved about 3%, or 100,000 BTUs, which had a value of $.70 per MBF. The benefit of energy savings would take about 23.8 years to pay back! Energy in this country, especially with wood fired boilers, is too cheap to save.
Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison.
Click on Wood Doctor Archives to peruse past answers.