Topic: Insulated thermal mass in a single wythe wall. I sell insulated concrete block with a continuous thermal barrier. (www.nrginsulatedblock.com). I have found that many companies make design decisions based on computer-based energy modelling programs that do not accurately account for insulated thermal mass. I found a discussion of the thermal time constant (TTC), which takes into account heat capacity, thermal lag time, and conduction through the insulation of insulated thermal mass. Although NRG walls consistently deliver HVAC energy savings of over 60%, compared to block walls with interior insulation (isolated thermal mass), using the DOE Commercial Buildings Energy Consumption Surveys as baseline, I find non-believers everywhere. Any tips for dealing with designers whose computer programs tell them that it is ok to put the insulation on the wrong side of the wall?
Thermal mass on the interior side of the insulation dampens interior temperature swings and can therefore reduce energy consumption. This can be modeled fairly simply in a program called “WUFI” available from Oak Ridge National Lab. Originally developed in Germany, the program is able to model thermal and moisture transport in materials.
For example, a wall with NRG block could be modeled and subjected to any of several U.S. climate data bases. The program calculates temperature and moisture profiles across the wall based on exterior/interior temperatures, solar incidence, orientation of the wall, etc. The calculations are done hourly for a year and whole-year graphs are then available for viewing/printing etc. A baseline comparison could be made with a CMU wall insulated with perlite or interior rigid insulation.
The difference requirments for insulation board at cavity wall & exterior walls
Topic: Insulated thermal mass in a single wythe wall. I sell insulated concrete block with a continuous thermal barrier. (www.nrginsulatedblock.com). I have found that many companies make design decisions based on computer-based energy modelling programs that do not accurately account for insulated thermal mass. I found a discussion of the thermal time constant (TTC), which takes into account heat capacity, thermal lag time, and conduction through the insulation of insulated thermal mass. Although NRG walls consistently deliver HVAC energy savings of over 60%, compared to block walls with interior insulation (isolated thermal mass), using the DOE Commercial Buildings Energy Consumption Surveys as baseline, I find non-believers everywhere. Any tips for dealing with designers whose computer programs tell them that it is ok to put the insulation on the wrong side of the wall?
Thermal mass on the interior side of the insulation dampens interior temperature swings and can therefore reduce energy consumption. This can be modeled fairly simply in a program called “WUFI” available from Oak Ridge National Lab. Originally developed in Germany, the program is able to model thermal and moisture transport in materials.
For example, a wall with NRG block could be modeled and subjected to any of several U.S. climate data bases. The program calculates temperature and moisture profiles across the wall based on exterior/interior temperatures, solar incidence, orientation of the wall, etc. The calculations are done hourly for a year and whole-year graphs are then available for viewing/printing etc. A baseline comparison could be made with a CMU wall insulated with perlite or interior rigid insulation.
The program is available as a free download at:
http://www.ornl.gov/sci/btc/apps/moisture/index.html