Reference Publication: Fairey, P. and Wichers, S. "Validation of EnergyGauge® USA Using the HERS BESTEST" submitted to Residential Energy Services Network. Florida Solar Energy Center, Cocoa, FL, December 15, 2004. Disclaimer: The views and opinions expressed in this article are solely those of the authors and are not intended to represent the views and opinions of the Florida Solar Energy Center. |
Validation
of EnergyGauge® USA
Using the HERS BESTEST
Philip
Fairey and Susan Wichers
Florida
Solar Energy Center (FSEC)
FSEC-DN-10-04
Abstract
This report presents results from the testing and validation of the EnergyGauge USA home energy rating software conducted using the HERS BESTEST procedures. The results show that EnergyGauge USA is an excellent and verifiable simulation program that is capable of meeting all national requirements for home energy rating software tools.
Table of Contents
HERS BESTEST (Judkoff & Neymark, 1995) is a verification procedure developed by the National Renewable Energy Laboratory (NREL) to determine the accuracy and effectiveness of the energy load prediction capability of software tools used for Home Energy Ratings. It uses a wide variety of building configurations and characteristics as test cases for the evaluation.
The procedure uses results from three, widely-used and well-validated, detailed building energy simulation software programs to develop a range of reasonable results for each of the test cases. The reference programs used to generate the test case results are as follows:
The results from these three reference programs are then statistically analyzed to determine the 90% confidence interval for each set of test case results. These 90% confidence intervals establish the range of acceptable results for each test case. The National Association of State Energy Officers' (NASEO) National Home Energy Rating Technical Guidelines and the Mortgage Industry's National Accreditation Procedures for Home Energy Rating Systems require that home energy rating software tools "pass" each test for each building configuration that the rating system software intends to evaluate.
The following test cases are provided by the HERS BESTEST procedure:
With the exception of Cases L322 and L324, each of the above test cases is simulated in Colorado Springs, CO to evaluate heating energy loads and in Las Vegas, NV to evaluate cooling energy loads.
Table 1 below consists of the 90% confidence intervals for the maximum and minimum ranges of allowable heating load predictions produced by the three reference programs compared against the heating energy load predictions of EnergyGauge USA in Colorado Springs, CO.
All EnergyGauge USA heating load results fall within the 90% confidence intervals required by national HERS standards.
Table 1 Annual Heating Load Results for Colorado Springs, CO |
|||
Test Case |
Range Minimum |
EnergyGauge |
Range Maximum |
L100 |
48.75 |
56.52 |
79.48 |
L110 |
71.88 |
79.10 |
103.99 |
L120 |
37.82 |
43.46 |
64.30 |
L130 |
41.82 |
44.74 |
53.98 |
L140 |
42.24 |
46.73 |
56.48 |
L150 |
40.95 |
48.95 |
71.33 |
L155 |
43.53 |
51.36 |
74.18 |
L160 |
48.78 |
57.00 |
81.00 |
L170 |
61.03 |
64.34 |
92.40 |
L200 |
106.41 |
125.25 |
185.87 |
L202 |
111.32 |
133.73 |
190.05 |
L302 |
56.12 |
57.67 |
86.90 |
L304 |
46.11 |
52.95 |
73.15 |
L322 |
73.71 |
98.25 |
111.69 |
L324 |
46.38 |
57.72 |
77.47 |
Heating Load Plots
Figures 1a and 1b below present the graphic representation of the data
contained
in Table 1 above.
Figure 1a. Heating load results for test cases L100-L160 using EnergyGauge USA in Colorado Springs, CO.
Figure 1b. Heating load results for test
cases L170-L324 using EnergyGauge USA in Colorado Springs, CO.
Table 2 below consists of the 90% confidence intervals for the maximum and minimum ranges of allowable cooling load predictions produced by the three reference programs compared against the cooling energy load predictions of EnergyGauge USA in Las Vegas, NV.
All EnergyGauge USA cooling load results fall within the 90% confidence intervals required by national HERS standards.
Table 2 Annual Cooling Load Results for Las Vegas, NV |
|||
Test Case |
Range Minimum |
EnergyGauge |
Range Maximum |
L100 |
50.66 |
54.50 |
64.88 |
L110 |
53.70 |
57.24 |
68.50 |
L120 |
47.34 |
50.14 |
60.14 |
L130 |
32.95 |
36.94 |
45.26 |
L140 |
19.52 |
24.69 |
30.54 |
L150 |
62.41 |
65.38 |
82.33 |
L155 |
50.08 |
52.84 |
63.06 |
L160 |
58.61 |
61.40 |
72.99 |
L170 |
41.83 |
41.89 |
53.31 |
L200 |
60.25 |
65.92 |
83.40 |
L202 |
52.32 |
53.50 |
75.95 |
Cooling Load Plots
Figures 2a and 2b give results from the cooling load tests using Las Vegas, NV as the climate.
Figure 2a. Cooling load results for test cases L100-L150 using EnergyGauge USA in Las Vegas, NV.
Figure 2b. Cooling load results for test
cases L155-L202 using EnergyGauge USA in Las Vegas, NV.
Heating Load Differential Results:
Table 3 below consists of the 90% confidence intervals for the maximum and minimum ranges of allowable heating load differential predictions produced by the three reference programs compared against the heating energy load differential predictions of EnergyGauge USA in Colorado Springs, CO.
All EnergyGauge USA heating load differential results save the ground contact results fall within the 90% confidence intervals required by national HERS standards. The ground contact results are highlighted in Table 3 and are examined in greater detail in the section entitled Comments on Slab and Basement Model Results.
Table 3 Annual Heating Load Differential Results for Colorado Springs, CO |
|||
L110-L100 |
19.36 |
22.58 |
28.12 |
L120-L100 |
-18.57 |
-13.06 |
-7.67 |
L130-L100 |
-27.50 |
-11.78 |
-5.97 |
L140-L100 |
-24.42 |
-9.79 |
-4.56 |
L150-L100 |
-12.53 |
-7.57 |
-3.02 |
L155-L150 |
-1.54 |
2.41 |
6.88 |
L160-L100 |
-3.72 |
.48 |
5.10 |
L170-L100 |
-7.12 |
7.82 |
17.64 |
L200-L100 |
56.39 |
68.73 |
107.66 |
L202-L100 |
-0.51 |
8.48 |
9.94 |
L302-L100 |
-3.29 |
1.15 |
14.50 |
L302-L304 |
5.66 |
4.72 |
17.75 |
L322-L100 |
15.17 |
41.77 |
39.29 |
L322-L324 |
21.25 |
40.57 |
28.22 |
Comments on Slab and Basement Model Results
Even though EnergyGauge USA falls within the BESTEST ranges for all individual load cases, it does not fall within all the ranges established for heating load differences. Table 3 shows that, for the slab (L302-L304) the difference is less than the minimum established by BESTEST and for the basement (L322-L100, L322-L324) differences, EnergyGauge USA load savings are greater than the maximum established by BESTEST. This result stems from the fact that EnergyGauge USA uses a slab and basement model published by LBNL (Winkleman, 1998) three years after the BESTEST procedure was developed. The reasons for these differences are not yet clear but they are being investigated and, if justified by the investigation, the ground model used by EnergyGauge will be adjusted in the future.
Heating Load Differential Plots
Figures 3a and 3b give results from the heating load differential (delta) tests using Colorado Springs, CO as the climate.
Figure 3a. Heating load differential
results for test cases L110-L160 using
EnergyGauge USA in Colorado Springs,
CO.
Figure 3b. Heating load differential
results for test cases L170-L324 using EnergyGauge USA in Colorado Springs,
CO. (See also Comments on Slab and Basement Model
Results above.)
Cooling Load Differential Results:
Table 4 below consists of the 90% confidence intervals for the maximum and minimum ranges of allowable cooling load differential predictions produced by the three reference programs compared against the cooling energy load differential predictions of EnergyGauge USA in Las Vegas, NV.
All EnergyGauge USA cooling load differential results fall within the 90% confidence intervals required by national HERS standards.
Table 4 Annual Cooling Load Differential Results for Las Vegas, NV |
|||
L110-L100 |
-0.98 |
2.74 |
7.84 |
L120-L100 |
-8.87 |
-4.36 |
0.68 |
L130-L100 |
-24.40 |
-17.56 |
-13.71 |
L140-L100 |
-38.68 |
-29.81 |
-27.14 |
L150-L100 |
8.72 |
10.88 |
20.55 |
L155-L150 |
-22.29 |
-12.54 |
-9.64 |
L160-L100 |
3.88 |
6.90 |
12.28 |
L170-L100 |
-15.74 |
-12.61 |
-4.83 |
L200-L100 |
6.63 |
11.42 |
21.39 |
L200-L202 |
2.03 |
12.42 |
14.86 |
Cooling Load Differential Plots
Figures 4a and 4b give results from the cooling energy load differential (delta) tests using Las Vegas, NV as the climate.
Figure 4a. Cooling load differential results for test cases L110-L150 using EnergyGauge USA in Las Vegas, NV.
Figure 4b. Cooling load differential results for test cases L150-L202 using EnergyGauge USA in Las Vegas, NV.
Judkoff, R. and J. Neymark, 1995. "Home Energy Rating System Building Energy Simulation Test (HERS BESTEST)," Vol. 1 and 2, Report No. NREL/TP-472-7332. National Renewable Energy Laboratory, Golden, Colorado 80401-3393. (This document also available online at http://www.nrel.gov/publications/.)
Winkelmann, F., 1998. "Underground Surfaces: How to Get Better Underground Surface Heat Transfer Calculation in DOE-2.1E," DOE-2 USER News, Vol. 19, No. 1, p. 6- 13. Lawrence Berkeley National Laboratory, Berkeley, CA.