Managed by UT-Battelle for the Department of Energy Weatherization Assistant: What’s New in Versions 8.4 and 8.5 Mark Ternes Mike Gettings Oak Ridge National Laboratory 2009 National Weatherization Training Conference July 22, 2009

2Managed by UT-Battelle for the Department of Energy Purpose of This Presentation  Discuss MHEA field test and analyses results that led to important technical changes in Version 8.4 –MHEA field validation (overall performance) –BESTEST (UA values and space-heating load) –RESNET procedures (energy consumption) –True-up using the MHEA field validation homes (overall performance)  Summarize potential program impacts from use of the revised MHEA  Identify and discuss other changes that have been made in Version 8.4 and 8.5

3Managed by UT-Battelle for the Department of Energy MHEA Field Validation Study  Validation performed at DOE request before full implementation of MHEA  Validation report published November 2007 (ORNL/CON-501)  Findings (86 homes) –MHEA over predicted space-heating energy savings of weatherization measures by ~200% on average per home –MHEA achieved an average realization rate of ~35% (actual savings divided by predicted savings)

4Managed by UT-Battelle for the Department of Energy Home Energy Rating System (HERS) Building Energy Simulation Test (BESTEST)  Uses a basic single-family, site-built house that is simplistic enough to be modeled in MHEA  10 different test configurations of this basic house –Insulation and infiltration levels –Glazing properties and orientation –Shading –Internal loads

Comparison of UA Calculations ComponentBESTESTMHEA (final) Floor – R Floor – R Wall – R Wall – R Wall – R Ceiling – R Ceiling – R Ceiling – R Windows – DP, wood, argon Windows – SP, metal Doors Infiltration – 0.67 ACH Infiltration – 1.5 ACH

6Managed by UT-Battelle for the Department of Energy Conclusions Regarding MHEA’s UA Calculations  Some deviations from BESTEST occur: –NOT because MHEA calculations are wrong –But because MHEA accurately reflects mobile home construction or for other explainable reasons  MHEA accurately calculates the UA-values of mobile home envelope components

7Managed by UT-Battelle for the Department of Energy Space-Heating Load Analysis  MHEA UA-values made to equal BESTEST values to focus the analysis on the load calculation engine  BESTEST criteria are based on the results from three hourly simulation programs –DOE-2 –BLAST –SERI-RES  Loads calculated for a Denver climate  Space-cooling loads not examined

Comparison of Space-Heating Loads Test configuration Annual space-heating load (MBtu) BESTEST rangeMHEA L100A48.75 to L110A71.88 to L120A37.82 to L130A41.82 to L140A43.24 to L150A40.95 to L155A43.53 to L160A48.78 to L170A61.03 to L200A to

Comparison of Change in Loads Test configuration Change in annual space-heating load compared to a base case (MBtu) BESTEST rangeMHEA L100A L110A19.36 to L120A to L130A-27.5 to L140A to L150A to L155A-1.54 to L160A-3.72 to L170A7.12 to L200A56.39 to

10Managed by UT-Battelle for the Department of Energy Conclusions Regarding MHEA’s Space- Heating Load Calculations  MHEA passes the BESTEST criteria for each of the 10 test configurations, usually falling near the midpoint of BESTEST’s allowable range  MHEA accurately calculates the space- heating load of a mobile home  MHEA’s loads essentially track BLAST and are about 3-9 MBtu higher than DOE-2

11Managed by UT-Battelle for the Department of Energy RESNET Procedures  Tests space-heating energy consumption calculations for various heating systems using the BESTEST base case test configuration  Compares energy consumption of one heating system to another –90% AFUE furnace to a 78% AFUE unit –9.85 HSPF heat pump to a 6.8 HSPF unit –Electric resistance furnace to a 6.8 HSPF heat pump  RESNET results are based on the results of six hourly simulation programs –Two DOE-2.1 tools –Two DOE-2.2 tools –Micropas version 6.5 –TRNSYS version 15

12Managed by UT-Battelle for the Department of Energy Results and Conclusions Regarding MHEA’s Space-Heating Energy Consumption Calculations  MHEA accurately calculates the space- heating energy consumptions of the tested systems Heating system comparison Change in space-heating energy consumption (%) RESNET rangeMHEA 78% to 90% AFUE gas furnace-13.3% to -11.6%-13.3% 6.8 to 9.85 HSPF heat pump-29.0% to -16.7%-18.3% 6.8 HSPF HP to electric furnace41.8% to 80.8%52.3%

13Managed by UT-Battelle for the Department of Energy So  MHEA found to accurately calculate: –UA-values –Space-heating loads (essentially equivalent to BLAST or DOE-2) –Space-heating energy consumptions  But re-analysis using the MHEA field validation mobile homes showed that: –MHEA still over predicted savings by 168% –MHEA still achieved a realization rate of only 37%

14Managed by UT-Battelle for the Department of Energy Modifications to True-Up MHEA Predictions to Field Validation Results  Modeling of field validation homes in MHEA –Turned off programmable thermostat measure (12% of the homes) –Floor insulation levels of 0 in. changed to 0.5 in. (14% of the homes)  Engineering modifications to MHEA –Changed MHEA’s internal load assumptions to be more consistent with HERS and NEAT –Reduced MHEA’s infiltration loads by ~25% –Added an R-value of 1 to the ceiling, floor, and walls  Applied a 0.6 correction factor to MHEA’s energy savings calculations

16Managed by UT-Battelle for the Department of Energy Results from True-Up Modifications  MHEA’s over prediction of energy savings reduced to just 28%  MHEA’s realization rate increased to 78%  Use of MHEA’s optional billing adjustment feature can further improve MHEA’s accuracy on individual homes –Over prediction of energy savings reduced to 16% –Realization rate increased to 87%

21Managed by UT-Battelle for the Department of Energy Simulation of Program Impacts from Use of the Revised MHEA  Compared recommendations from the revised MHEA (Version 8.4) to the original (Version 8.3) –Frequency that measures are recommended –Average investment levels per home  18 mobile homes in Ohio –13 heated by natural gas –5 electrically heated  Columbus weather (5723 HDD)  State-supplied fuel and installation costs  Included health & safety and repair items

22Managed by UT-Battelle for the Department of Energy Program Impact Results and Conclusions  Use of the revised MHEA does NOT eliminate the recommendation of insulation measures –Roof: from 72% of the homes to 61% –Floor: from 89% of the homes to 61% –Wall: 17% for both versions of MHEA –Storm windows: 83% of the homes to 39%  Average investment levels remained high –Average investment per home dropped from $2832 to $2193 –Recommended investment level changed less than $130 in 39% of the homes

23Managed by UT-Battelle for the Department of Energy MHEA Steering Committee Comments  MHEA is now more accurate –Estimated energy savings and SIRs are more reasonable  The changes made in the revised MHEA move the recommendations in the right direction –Measures with questionable economics – like storm windows or insulating a roof with a decent amount of insulation in it – are less likely to be recommended  Recommend issuing the revised MHEA once remaining programming issues are resolved

24Managed by UT-Battelle for the Department of Energy Conclusions  MHEA’s basic engineering calculations were found to be accurate  Several adjustments had to be introduced into MHEA to make its energy estimates agree with measured field data  Recommendations appear to be reasonable  Program impacts compared to Version 8.3 appear to be reasonable and as expected  Final report published December 2008 (ORNL/CON-506)  Version 8.4 of the Weatherization Assistant with the revised MHEA was released November 14, 2008