DEC REQUEST DS2012-020 STAFF ANALYSIS

ISSUE: DS2012-020. Petitioner seeks a Declaratory Statement on an interpretation of Table 402.1.1.3 of the Florida Building Code, Energy Conservation.

Petitioner in DS2012-020 seeks clarification of the following questions:

1. Are the U-values for mass walls incorrect as listed in Table 402.1.1.3 (reference by prescriptive path Section 402.1.1.2) and its applicable footnote b? Are the U-values stated in Table 402.1.3 in violation of Florida Law, because these values contradict the value of thermal mass by requiring more insulation on the exterior of the wall than the interiod side of the wall?

2. If only the insulation for mass walls, as shown in Table 402.1.1 and Table 402.1.1.3 meets the applicable R-factor or U-factor, does this alone constitute “compliance with th Florida Energy Code”, or must all footnotes contained within Table 4021.1.3 also be met in order to use the prescriptive path?

3. How has the compliance software and applicable reports derived from this software address the discrepancies in the insulation values for mass walls using the prescriptive compliance path as well as the requirement that ALL footnotes shown in Table 402.1.1 and Table 402.1.1.3 must be met before compliance with the Florida Energy Code can be claimed.

Situation:

Ms. Lorraine A. Ross, representing The Dow chemical Company, seeks clarification of required insulation levels for mass walls utilizing the prescriptive compliance path in the Florida Energy Code, Chapter 4, which addresses energy efficiency provisions for residential construction. Dow has been working with several insulation distributors, including G. Prouix of Fort Lauderdale, BlueLynx of Miami and All Interior Supply of Orlando and Hialeah, firms that are often asked questions regarding insulation requirements of the Florida Energy Code. Dow is committed to providing complete and accurate information regarding compliance with the Energy Code to its customers, including distributors, home builders, architects and other design professionals. To that end, Dow, along with these distributors, found that there is a discrepancy in insulation values for mass walls using the prescriptive compliance path in Chapter 4, Residential, of the Florida Building Code, Energy Conservation.

With respect to the prescriptive compliance path of the Florida Energy Code, Section 402.1.2 requires compliance with Table 402.1.1. It then offers three options:

· If Section 402.1.1.1, R-value computation method is chosen, the insulation required for mass walls is R-6 if the insulation is on the exterior of the wall and R-7.8 as stated in footnote i if more than half the insulation is on the interior of the wall.

· If Section 402.1.1.2, the U-factor alternative is chosen, the referenced Table 402.1.1.3 states that the insulation for mass walls is a U-factor of 0.124 (equivalent R-8) on the exterior of the wall and a U-factor of 0.165 (equivalent R-6) as stated in footnote b if more than half the insulation is on the interior of the wall.

· Since both methods are considered under the Prescriptive compliance path, these values for mass wall insulation should not be in conflict.

This declaratory statement requests recognition of a significant error for mass wall insulation in Table 402.11.3 footnote b (referred to in Section 402.1.1.2) that, if left uncorrected, results in less efficient homes than if any other prescriptive compliance path is taken.

Background:

1. Table 402.1.1 and Table 402.1.1.3 were intended to provide equivalent overall U-factors.

2. The Mass wall U-factor to be used in the Total UA Alternative is U-0.124 (statewide) or a total R of 8.065, roughly representing an R-7.8 interior insulated hollow concrete block wall. Footnote b to Table 402.1.1.3 in the original version read, “When more than half the insulation is on the exterior, the mass wall U-factor shall be a maximum of 0.165” (roughly R-6 insulation). During the Glitch fix cycle, staff proposed changing Footnote b from “exterior” to “interior” to agree with the IECC. In effect, what happened was that the footnote was intended to deal with the exterior wall (which had an insulation R-value of R-6 in Florida’s Table 402.1.1) but ended up comparing the block wall with interior insulation to an R-6 while leaving the exterior wall compared to an R-7.8 insulation.

Petitioner maintains that this one word change in Footnote b of Table 402.1.1.3 results in a less efficient mass wall than is required. This means that when insulation is added to the interior of a mass wall it needs only to comply with the equivalent of an R-6 not the intended R-7.8 equivalent. This error causes over a 20% deficiency in thermal performance for mass walls if the U-factor alternative compliance path is chosen. Petitioner is concerned that these erroneous values are included in the software used to demonstrate compliance with the Florida Building Code, Energy Conservation.

3. Petitioner maintains there is an inherent conflict in thermal performance between Table 402.1.1 and Table 402.1.1.3 as shown:

Mass Walls – Insulation levels	R-value if insulation is on the exterior	R-value if half insulation is on the interior of the wall
Table 402.1.1	6	7.8
Tale 402.1.1.3 (converting U-factor to R-value*)	8	6

*the lower the U-factor, the higher the R-value

Building science dictates that placing insulation on the exterior of mass walls in the Florida climate is more efficient due to the mass effect. The 2009 International Energy Conservation Code implies this relationship as well by the required efficiencies for exterior (R-4) vs interior (R-6) insulation on mass walls in Table 402.1 of that document. Therefore, the R-values cited in Table 402.1.1 of the 2010 Florida Building Code, Energy Conservation of R-6 for insulation placed on the exterior side of the wall and R-7.8 when more than half the insulation is on the interior side of the wall are correct.

4. Petitioner further maintains that mass wall insulation, as currently stated in Table 402.1.1.3 Footnote b (referred to in Section 402.1.1.2) is in violation of Florida Statutes. Energy-related legislative materials circulated by the Florida Building Commission staff in preparation for the March 7, 2012 meeting of the Energy TAC stated:

“Code for new buildings shall take into account exterior envelope physical characteristics (including thermal mass); HVAC, service water heating, energy distribution, lighting, energy managing & auxiliary systems design, selection, configuration and performance. [553.904, 553.905, FS]” (emphasis added)

Requiring more insulation on the exterior of the mass wall than on the interior of the mass wall negates the thermal mass effect in Florida climates and is therefore in violation of Florida law.

5. For this DEC analysis, staff calculated code compliance for a 2,000 square foot home using REScheck 4.3.3 (review only) and EnergyGauge USA 3.0. The home was 40’ x 50’ with a 17 foot garage wall on the 50 foot side, R-30 flat ceiling; 1,304 square feet of concrete block wall with R-5 insulation (interior and exterior cases), 136 square feet of R-13 16”oc frame wall around the garage, 400 square feet (20% of CFA) of double pane low-E windows (0.65 U-factor and 0.30 SHGC), with 40 square feet of solid door; and 163 linear feet of R-0 unheated slab-on-grade. All prescriptive requirements are assumed met.

a. REScheck analysis

Requirement where Requirement where

insulation is on the insulation is on the

Results: interior wall, U= 0.165 exterior wall, U=0.165

R-5 interior insulation Passes + 0.6% Fails - 5.0%

R-5 exterior insulation Fails - 5.0% Passes + 0.6%

b. EnergyGauge USA analysis. An E-ratio of 0.80 or less PASSES code:

E-ratio Interior R-5 E-ratio Exterior R-5

Tallahassee .80 .78

Tampa .78 .75

Miami .79 .77

6. Petitioner also questions whether additional criteria must be met beyond the building envelope to comply with the code. Section 402.1.1.3, Total UA alternative, states:

“If the total building thermal envelope UA (sum of U-factor times assembly area) is less than or equal to the total UA resulting from using the U-factors in Table 402.1.1.3 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table 402.1.1. All other prescriptive criteria of Table 402.1.1, the prescriptive criteria in Section 402.1.2.4 and footnotes to Table 402.1.1.3 shall be met. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The SHGC requirements of Table 402.1.1 shall be met in addition to UA compliance.” (emphasis added)

7. It has been pointed out that U-factors referenced in the code do not adequately reflect the values of typical CBS construction in Florida. The following table was provided by Rob Vieira of the Florida Solar Energy Center. It contains information on U-value calculations utilized in the EnergyGauge USA program. Note that an air space is included for the exterior insulation case but not with the interior insulation case because the more typical construction practice where the insulation is between the furring strips is assumed. When the code is changed, these more accurate U-factors should be used in Table 402.1.1.3.

INSULATION POSITION	Inside	Outside
Outside Film	0.17	0.17
Stucco	0.1999	0.1999
Ext R Value	0	6
Block	1.1002	1.1002
Interior R Value	7.8	0
Air Space	0	0.92
Drywall	0.4508	0.4508
Inside Film	0.68	0.68
Soil	0	0
Total R in Series	10.4009	9.5209
1/R Total	0.096146	0.105032
software check	yes	yes

Staff Recommendations: Based on the above facts and circumstances, staff provides the following recommendations as answers to proponent’s questions:

Question1:

To the question, Are the U-values for mass walls incorrect as listed in Table 402.1.1.3 (reference by prescriptive path Section 402.1.1.2) and its applicable footnote b? the answer is:

Option 1: No, the code reflects code changes as approved by the Commission.

Option 2: Yes. Table 402.1.1.3, Equivalent U-Factors, was intended to reflect the R-values in Table 402.1.1. Table 402.1.1.3 now compares the U-factor for insulation located on the interior of mass walls to that specified for insulation located on the exterior of mass walls in Table 402.1.1. Thus, footnote b should be corrected to read: “When more than half the insulation is on the exterior interior, the mass wall factors shall be a maximum of 0.165.”

To the question, Are the U-values stated in Table 402.1.1.3 in violation of Florida Law, because these values contradict the value of thermal mass by requiring more insulation on the exterior of the wall than the interior side of the wall? the answer is that this question is beyond the scope of this DEC statement.

Question 2:

To the question, If only the insulation for mass walls, as shown in Table 402.1.1 and Table 402.1.1.3 meets the applicable R-factor or U-factor, does this alone constitute “compliance with the Florida Energy Code”, or must all footnotes contained within Table 4021.1.3 also be met in order to use the prescriptive path? the answer is that all other prescriptive criteria of Table 402.1.1, the prescriptive criteria in Section 402.1.2.4 and footnotes to Table 402.1.1.3 shall also be met.

Question 3:

To the question, How has the compliance software and applicable reports derived from this software addressed the discrepancies in the insulation values for mass walls using the prescriptive compliance path as well as the requirement that ALL footnotes shown in Table 402.1.1 and Table 402.1.1.3 must be met before compliance with the Florida Energy Code can be claimed? the answer is that this question is beyond the scope of this DEC statement.