In addition to human error in data entry there are two main reasons why a Rescheck Report may fail: Windows and, to some extent, Insulation.
Window are typically one of the most frequent causes of failure of a Rescheck report especially if the information provided is inaccurate or vague. Windows are very important in the overall energy analysis of the building because they are the main source of heat loss and gain.
Some of the errors that are likely to be made with respect to windows that may cause Rescheck failures include:
Incorrect U-values: The U-value is the measure of the rate of heat transfer through a window. If the wrong U-value is used (for example, for conventional windows when energy efficient windows were used), the energy performance of the building will be calculated incorrectly.
SHGC (Solar Heat Gain Coefficient): This is the measure of the quantity of solar heat that a window admits into the building. The wrong SHGC values can lead to the wrong computation of heating and cooling loads and thus lead to wrong energy compliance report.
Window area or number of windows: If the total area of windows or the number of windows is wrongly indicated, this may affect the overall thermal performance of the building and make it non-compliant.
Failure to distinguish window types: Some windows have special features such as Low-E coatings or are double glazed which greatly enhance energy efficiency. This is because in the real world there are two categories of windows, the standard windows which are not very efficient and the more efficient windows, and this is what makes the generation of the incorrect report. These problems are quite frequent because windows can be quite different in their performance and selecting wrong information about them can easily lead to non-compliance.
On the other hand, while insulation is a very important factor in the energy performance of a building, it is not the number one reason why a Rescheck report fails to pass code. However, incorrect insulation data is almost equal to causing Rescheck failures.
Here’s why insulation plays a major role:
Wrong R-values: Insulation works by resisting the flow of heat and this is measured by the R-value. If the R-value of the walls, ceiling, floor, or any other component of the thermal envelope is put wrong (say R-13 when the actual insulation is R-19), the Rescheck software will get the building’s thermal resistance wrong and could produce a non-compliant report.
Wrong insulation or wrong method of application or both: If the software is not informed of the type of insulation material or the method of application of insulation (spray foam, fiberglass batt, blown-in insulation), the thermal performance may be assumed to be worse than the actual and this may result in errors in the compliance report.
Uninsulated regions: At times, some areas of the building may not be adequately insulated or may not have insulation at all, and this may be omitted in the Rescheck report, which would give faulty results.
Although insulation is an important part of achieving energy codes and can cause a Rescheck failure if the information is incorrect, windows (primarily U-values or SHGC) are usually the most common cause of failure. This is because windows, because of their importance in heat gain and loss, are more likely to be inaccurate and less precise than insulation data which is more consistent.
Therefore, while insulation is an important determinant of energy performance and compliance, window data is the major cause of Rescheck failures. This is because windows are very crucial in the loss and gain of heat and therefore more likely to be inaccurate or incorrect as opposed to insulation data which is more accurate and precise.