[Code of Federal Regulations]
[Title 10, Volume 3]
[Revised as of January 1, 2005]
From the U.S. Government Printing Office via GPO Access
[CITE: 10CFR434.516]

[Page 403-404]
 
                            TITLE 10--ENERGY
 
                    CHAPTER II--DEPARTMENT OF ENERGY
 
PART 434_ENERGY CODE FOR NEW FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH 
RISE RESIDENTIAL BUILDINGS--Table of Contents
 
          Subpart E_Building Energy Cost Compliance Alternative
 
Sec. 434.516  Building exterior envelope.

    516.1 Insulation and Glazing. The insulation and glazing 
characteristics of the Prototype and Reference Building envelope shall 
be determined by using the first column under ``Base Case'', with no 
assumed overhangs, for the appropriate Alternate Component Tables (ACP) 
in Table 402.4.1.2, as defined by climate range. The insulation and 
glazing characteristics from this ACP are prescribed assumptions for 
Prototype and Reference Buildings for calculating the Energy Cost 
Budget. In calculating the Design Energy Consumption of the Proposed 
Design, the envelope characteristics of the Proposed Design shall be 
used.
    516.2 Infiltration. For Prototype and Reference Buildings, the 
infiltration assumptions in subsection 516.2.1 shall be prescribed 
assumptions for calculating the Energy Cost Budget and default 
assumptions for the Design Energy Consumption. Infiltration shall impact 
perimeter zones only.
    516.2.1 When the HVAC system is switched ``on,'' no infiltration 
shall be assumed. When the HVAC system is switched ``off,'' the 
infiltration rate for buildings with or without operable windows shall 
be assumed to be 0.038 cfm/ft\2\ of gross exterior wall. Hotels/motels 
and multi-family high-rise residential buildings shall have infiltration 
rates of 0.038 cfm/ft\2\ of gross exterior wall area at all times.
    516.3 Envelope and Ground Absorptivities. For Prototype and 
Reference Buildings, absorptivity assumptions shall be prescribed 
assumptions for computing the Energy Cost Budget and default assumptions 
for computing the Design Energy Consumption. The solar absorptivity of 
opaque elements of the building envelope is assumed to be 70%. The solar 
absorptivity of ground surfaces is assumed to be 80% (20% reflectivity).
    516.4 Window Management. For the Prototype and Reference Building, 
window management drapery assumptions shall be prescribed assumptions 
for setting the Energy Cost Budget. No draperies shall be the default 
assumption for computing the Design Energy Consumption. Glazing is 
assumed to be internally shaded by medium-weight draperies, closed one-
half time. The

[[Page 404]]

draperies shall be modeled by assuming that one-half the area in each 
zone is draped and one-half is not. If manually-operated draperies, 
shades, or blinds are to be used in the Proposed Design, the Design 
Energy Consumption shall be calculated by assuming they are effective 
over one-half the glazing area in each zone.
    516.5 Shading. For Prototype and Reference buildings and the 
Proposed Design, shading by permanent structures, terrain, and 
vegetation shall be taken into account for computing energy consumption, 
whether or not these features are located on the building site. A 
permanent fixture is one that is likely to remain for the life of the 
Proposed Design.