## 3.1 Overview

This chapter covers building envelope features and compliance strategies and highlights the energy code requirements that affect the design of the building envelope for newly constructed low-rise residential buildings. See Chapter 9 for more information on alterations and additions.

The design of envelope components can significantly affect the energy demand needed to meet heating and cooling loads to maintain the desired inside comfort temperature of the building.

Heating and cooling load calculations are used to determine the mechanical system design needed for space heating and cooling.

• Heating Loads: The principal components of heating loads are infiltration and conduction losses through building envelope components, including walls, roofs, floors, slabs, windows, and doors.

o Example: A dwelling unit located in Climate Zone 16 typically has a large heating load due to moderate summers, cool temperatures, and snow cover that predominates for more than half of the year.

• Cooling Loads: Cooling loads are dominated by solar gains through windows, skylights, and roof/attic assemblies.

o Example: A dwelling unit located in Climate Zone 15 typically has a large cooling load due to extremely hot and dry summers and moderately cold winters.

### 3.1.1 Navigating This Chapter

This chapter is organized by building envelope component as seen in the Table of Contents.

This chapter includes:

• An overview of changes to building envelope requirements for the 2019 Energy Standards

• A description of fenestration terminology, requirements and labeling, U-factor, solar heat gain coefficient (SHGC) requirements, and credits that can be used under the performance approach.

• Description of opaque envelope terminology, requirements related to insulation, roof products, radiant barriers, air barriers, vapor retarders, and attic ventilation

• Compliance approaches for alternative construction assemblies such as log homes, straw bale, structural insulated panels (SIPs) and insulated concrete form (ICF) construction

Role Icons. The content of this chapter applies to multiple roles in the compliance process. The icons shown in Figure 3-1 are used to identify information that is specific to individual roles to help navigate the compliance process.

Figure 3-1: Role Icons

| Designer |  | Plans Examiner
| Contractor/Installer |  | Building Inspector
| HERS Rater/ATT |  | Energy Consultant