The Department will determine compliance as follows:

(a) The first sample size (n1) must be four or more units, except as provided by § 429.57(e)(1)(ii).

(b) Compute the mean of the measured energy performance (x1) for all tests as follows:

where xi is the measured energy efficiency or consumption from test i, and n1 is the total number of tests.

(c) Compute the standard deviation (s1) of the measured energy performance from the n1 tests as follows:

(d) Compute the standard error (sx1) of the measured energy performance from the n1 tests as follows:

(e)(1) For an energy efficiency standard (EES), determine the appropriate lower control limit (LCL1) according to:

And use whichever is greater. Where EES is the energy efficiency standard and t is a statistic based on a 97.5 percent, one-sided confidence limit and a sample size of n1.

(2) For an energy consumption standard (ECS), determine the appropriate upper control limit (UCL1) according to:

And use whichever is less, where ECS is the energy consumption standard and t is a statistic based on a 97.5 percent, one-sided confidence limit and a sample size of n1.

(f)(1) Compare the sample mean to the control limit.

(i) The basic model is in compliance and testing is at an end if:

(A) For an energy or water efficiency standard, the sample mean is equal to or greater than the lower control limit, or

(B) For an energy or water consumption standard, the sample mean is equal to or less than the upper control limit.