This method uses calculations of the “U” value of all the building components and making sure that they meet the minimum required by the code. This is the traditional way to show compliance, but is probably the most difficult and time consuming methods and we don’t expect many people to use it. If you do use this method please include you calculations with your permit application.
This method uses “Prescriptive Packages”. These are pre-calculated, or custom calculated packages of insulation determined by the percentage and efficiency of the glazing used. This is probably the easiest method to use, especially for simpler designs and homeowners. To use this method you must know the percentage of glazing to solid walls and the “U” value of the glazing. Most window manufactures make the “U” values available in their catalogs or on their web sites. A chart of generic “U” values is included with the Prescriptive Package Chart, but if you are using “Low-E” or “High Performance” glass using the manufactures numbers may save substantially on insulation. (Remember the lower the “U” values the better the insulation value of the window)
A Prescriptive Package Chart listing 35 different packages is available for download in the PDF format. The first 11 packages take advantage of a trade off allowed by the State of New Jersey where you can eliminate the basement wall insulation if you install high efficiency heating and cooling equipment (High Efficiency Heating means a furnace AFUE of 90% or more, or a heat pump HSPF of 7.8 or more. High Efficiency Cooling means a SEER of 12 or more). If you are using this method please fill out the Prescriptive Package Worksheet and submit it with your application.
If you can’t find a package, on the chart listed above, that works with your windows, or just want the computer to do all the work, you may go the the Department of Energy’s web page and use the Prescriptive Package Generator. This is an online application and does not require the download of any software. To use this application just enter the percentage of glazing and it’s “U” value and you will be provided with a package of insulation values to choose from. This option also has a great feature of generating a completed compliance report that you should submit with your application.
This method uses the REScheck software, which is available for free download. This method can take advantage of tradeoffs allowed in the code and may be the best choice for homes with large areas of glass, more complex designs and provide the most cost effective construction methods. To take advantage of the trade-off in basement insulation for high efficiency heating and cooling equipment don’t enter any Basement Wall area or the Mechanical Section and just note on the printout that you are taking advantage of the trade-off. Be sure to down load and read the user guide that is available for this method. If you are using this method please print-out the Compliance Report and Inspectors Check List and submit them with you application.