Article #1461 - REScheck Webcast Questions - Sunrooms and Additions
This article is based on questions asked during both the May 6, 2005 REScheck Training Webcast
and the July 28, 2005 REScheck Training Rebroadcast as well as questions received through email following these events. The original language of the questions and answers has been modified to make them as generic as possible while retaining the applicable specific information.
Does sunroom criteria apply to New York state code?
Yes, the sunroom requirements became effective in the 2001 IECC which NY has adopted. Therefore, if the addition meets the criteria defined in the code as a sunroom, the alternative prescriptive table can be used to show compliance. For more information on sunrooms, the latest issue of Setting the Standard Newsletter included an article on Special Code Requirements for Sunrooms and additions.
What if you have a project where you are constructing an addition to a house and a new roof on the old house what do you do?
First suggestion would be to show compliance to the addition separately. This would include the square footage of the new roof that only defines the addition area.
Second suggestion would be to show compliance for the roof as an individual component. Your location and heating degree days (HDD) will define the minimum amount of insulation that would be required in the new roof construction. For this approach, the IECC references several figures dependent upon the assembly component; again the HDD will determine the minimum U-factor of the roof assembly. For additional help on determining compliance to the roof assembly, please feel free to contact tech support at techsupport@becp.pnl.gov.
Third suggestion, if you cannot get the addition by itself to meet code (which is not uncommon due to the fact that the window wall ratio is only based upon the new two to three exterior walls of the addition that can be shown for compliance), try to show compliance for the entire house including the new addition. The new roof upgrade with the required amount of insulation might get you into compliance. For this approach, I would suggest using REScheck to run your take offs that define the building envelope.
The following link offers additional information on this subject:
Entering an Addition in the REScheck Software
Does a sunroom's perimeter get calculated into the exterior wall square footage of the building if the IECC tables are going to be used?
The prescriptive envelope component criteria in the 2003 International Energy Conservation Code (IECC) is an alternative compliance path for sunrooms and additions to existing residential buildings and structures.
The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. The SHGC is the fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits.
Sunrooms and/or additions that meet the criteria defined in the 2003 IECC can show compliance by using the Prescriptive Envelope Component Criteria table below for the designated heating degree days (HDD) applicable to the location.
TABLE 1 2003 IECC/Sunrooms (Section 502.2.5)
| HDD (heating degree day) | Fenestration U-factor (MAX) | Ceiling R-value (MIN) | Wall R-value (MIN) | Floor R-value (MIN) | Basement wall R-value (MIN) | Slab perimeter R-value and depth (MIN) | Crawl space wall R-value (MIN) |
|---|---|---|---|---|---|---|---|
| 0 - 1,999 | .75 | R-19 | R-13 | R-11 | R-5 | R-0 | R-5 |
| 2,000 - 3,999 | .50 | R-19 | R-13 | R-19 | R-8 | R-5, 2 ft. | R-10 |
| 4,000 - 5,999 | .50 | R-19 | R-13 | R-21 | R-10 | R-9, 2 ft. | R-19 |
| 6,000 - 8,499 | .50 | R-24 | R-13 | R-21 | R-11 | R-13, 4 ft. | R-20 |
| 8,500 - 12,999 | .50 | R-24 | R-13 | R-21 | R-19 | R-18, 4 ft. | R-20 |
TABLE 2 2003 IECC/Additions (Section 502.2.5)
| HDD (heating degree day) | Fenestration U-factor (MAX) | Ceiling R-value (MIN) | Wall R-value (MIN) | Floor R-value (MIN) | Basement wall R-value (MIN) | Slab perimeter R-value and depth (MIN) | Crawl space wall R-value (MIN) |
|---|---|---|---|---|---|---|---|
| 0 - 1,999 | .75 | R-26 | R-13 | R-11 | R-5 | R-0 | R-5 |
| 2,000 - 3,999 | .50 | R-30 | R-13 | R-19 | R-8 | R-5, 2 ft. | R-10 |
| 4,000 - 5,999 | .40 | R-38 | R-18 | R-21 | R-10 | R-9, 2 ft. | R-19 |
| 6,000 - 8,499 | .35 | R-49 | R-21 | R-21 | R-11 | R-13, 4 ft. | R-20 |
| 8,500 - 12,999 | .35 | R-49 | R-21 | R-21 | R-19 | R-18, 4 ft. | R-20 |
The suite of REScheck software tools cannot be used to show compliance using the prescriptive criteria alternative compliance defined for sunrooms and additions in the 2003 IECC. Compliance can be shown on your building plans by verifying the criteria and minimum component insulation and maximum u-factor for fenestration have been met. Attaching the applicable table and reference to your building plans can also be used for documentation.
Does REScheck accommodate values for isocyuranate installations?
The R-value for isocyanurate insulation is entered in REScheck in the same manner as other insulation material.
When do existing buildings need to be brought up to code?
Existing buildings are not required to be brought up to code unless the exterior building envelope or any energy related parts or portions are being changed (such as window replacements, roof replacement, additions, lighting, service water heating, and HVAC systems).
In an addition, would I enter all of the walls including the shared wall with the existing part of the house?
Insulation and energy code requirements for additions are for the new exterior walls only. The common wall between the existing and new addition would be considered a wall between two conditioned spaces and therefore should not be included in your compliance reporting.
Refer to Energy Code Requirements for Sunrooms and Additions for more information.