CHAPTER 1: OVERVIEW OF ENERGY EFFICIENT CONSTRUCTION

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1 Chapter 1: Overview of Energy Efficient Construction 1 CHAPTER 1: OVERVIEW OF ENERGY EFFICIENT CONSTRUCTION Chapter 1 is a quick reference guide that discusses the key components and features of energy efficient construction, and overall site planning. In addition, four common home designs (shown in cross-section) illustrate how to integrate these energy efficient features. When these key components are incorporated into a home design they save money spent on utilities, improve indoor air quality, enhance comfort, prevent moisture problems, and increase the long-term durability of the building. Features of the key components are discussed in the following pages and are described in the other chapters. Details of how to implement these innovations must be included in the plans and specifications for the home. The details must be described thoroughly to the subcontractor responsible for their installation. Too often, an excellent plan falls short of expectations because of inadequate attention to details.

2 2 Chapter 1: Overview of Energy Efficient Construction ENERGY EFFICIENT HOMES: THE KEY COMPONENTS AND THEIR FEATURES AIR BARRIER SYSTEM (CHAPTER 4) An air barrier system eliminates leakage between conditioned and unconditioned spaces. Seal all openings between living areas and crawl spaces, unheated basements, attics, and garages MOISTURE BARRIER SYSTEM (CHAPTER 4) An effective moisture barrier system keeps bulk (free) moisture from wood framing and interior of home. Drain water away from the foundation Install capillary breaks Use 6 mil polyethylene ground cover Carefully flash roof details, around windows and doors, and over other roof and wall penetrations through which wind-driven rain may leak CONTINUOUS INSULATION SYSTEM (CHAPTER 5) A continuous insulation system creates as unbroken an insulation layer as possible between conditioned and unconditioned spaces, such as: Foundation walls, exterior framed walls, floors over unconditioned or exterior spaces, ceilings below unconditioned or exterior spaces (including attic access covers) Wall areas adjacent to attic spaces or basement spaces, such as knee walls, attic stairways, and high interior walls with attic or exterior space Behind wall areas between conditioned and unconditioned spaces, such as band joists, garage walls, basement stairways, and mechanical room walls ENERGY EFFICIENT FRAMING (CHAPTER 5) Energy efficient framing reduces thermal bridging by using fewer solid members in the walls to increase the overall R-value of the wall. Use advanced framing techniques Use insulated headers

3 Chapter 1: Overview of Energy Efficient Construction 3 ENERGY EFFICIENT WINDOWS AND DOORS (CHAPTER 6) Energy efficient windows and doors must be properly located and installed. Design home with minimal east and west glass area Locate additional glass area on south side for passive heating in winter months Consider passive solar designs to further reduce heating needs Use double-paned windows with low-emissivity coatings and other high performance features (Ufactors less than 0.35) Shade windows in summertime with overhangs or glazing treatments ENERGY EFFICIENT HEATING AND COOLING SYSTEMS (CHAPTER 7) Energy efficient heating and cooling systems utilize high efficiency equipment designed for the local climate. These systems must be both properly sized and installed. Locate equipment in conditioned spaces Use sealed combustion devices to eliminate potential for backdrafting PASSIVE RADON SYSTEM (CHAPTER 7) Install a passive radon system to minimize expenses of a potential problem. Radon is a cancer-causing, radioactive gas. Cost of converting a passive system to an active system is much less than having to install an entire radon mitigation system ENERGY EFFICIENT DUCTWORK (CHAPTER 8) Energy efficient ductwork supplies proper airflow to provide adequate comfort conditioning if the size and layout of the ductwork are correct. Measure airflow to guarantee balance and comfort Locate ductwork in conditioned spaces Seal all duct leaks, except those in removable components, with mastic or mastic plus fiber mesh; seal leaks around removable components with tape having UL-181 A or B rating Have ductwork pressure tested for tightness Reduce the amount of flexible ductwork and made sure it does not have sharp bends WATER HEATING (CHAPTER 9) Saving energy, while heating water, requires selection of efficient equipment. Use heat traps to prevent convective loops Install water heater wraps Install energy efficient water heaters Use hot water conserving fixtures and appliances

4 4 Chapter 1: Overview of Energy Efficient Construction ENERGY EFFICIENT APPLIANCES AND LIGHTING (CHAPTER 10) Energy efficient appliances and lighting reduce a home s operating costs. Install fluorescent or compact fluorescent lamps, if operating for more than 4 hours per day Use recessed lighting fixtures selectively. Choose only insulation contact (IC) rated lighting fixtures Use high-pressure sodium or metal halide lamps for exterior lighting (daylight sensors needed if used for security lighting) Select ENERGY STAR rated appliances OVERALL SITE PLANNING To enhance the energy efficiency of a home that incorporates these key components, the home must also be located properly on the lot to best utilize the environment. Landscaping is added and used to full advantage. Figure 1-1 contains general site planning and landscaping guidelines that will aid in creating an energy efficient home. Builders have limited options about the orientation of a home on most building lots; therefore, the developer must consider home orientation when planning a subdivision. Builders can modify house plans, to some extent, to ensure that glassed areas are properly located with the majority of the glassed areas being oriented within 20 degrees of south. In Figure 1-1, the length of the house (with many glass windows) faces south in order to take advantage of the winter sunlight. The following eight general site planning and landscaping guidelines can be located in Figure 1-1. Site planning and landscaping guidelines include: 1. Major glassed areas are oriented to the south within 20 degrees; overhangs provide summer shade, but do not block winter sunlight. 2. A garage to the west blocks summer sun and winter winds. 3. Deciduous trees shade east, west, southeast, southwest, and northeast sides in the summer. 4. A windbreak of evergreen trees and shrubs to the north will buffer winter winds. 5. A trellis, with deciduous vines, shades the east wall. Windows should be limited on the east side, which receives early morning sun. 6. Ground cover reduces reflected sunlight. 7. Gutter systems direct water away from the foundation. 8. Water is removed from the foundation, using a continuous foundation drain in a gravel bed, with a fabric filter connected.

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6 6 Chapter 1: Overview of Energy Efficient Construction FOUR HOME DESIGNS THAT INCORPORATE ENERGY EFFICIENT FEATURES The following four home cross-sections show how the key components of energy efficient home construction can be adapted to a number of basic homes. These components can be mixed in various combinations to achieve an energy efficient home. Figure 1-2 shows a two-story home cross-section with a conditioned basement. The attic is not used for storage or HVAC. Attic access is only provided to locate a roof leak. HVAC is provided to the second floor by the use of a duct chase from the basement through the floor trusses on the second floor that contain the duct system. The HVAC system can be located any place, other than the attic, in this cross-section. Figure 1 2 Two-story Home Cross-section with a Conditioned Basement, No Attic Use

7 Chapter 1: Overview of Energy Efficient Construction 7 Figure 1-3 shows a two-story home cross-section with a conditioned mini-basement (crawl space) that uses the attic for HVAC and storage. To keep the HVAC system in a conditioned space, the rafters are insulated. The attic is now considered to be within the insulated envelope of the home. The ceiling joists must be designed to support the additional load and vibration of the HVAC system and to support any storage load. Figure 1 3 Two-story Home Cross-section with a Conditioned Mini-Basement (Crawl Space); Attic used for HVAC and Storage

8 Chapter 1: Overview of Energy Efficient Construction Figure 1-4 shows a two-story home cross-section with a vented crawl space, insulated floor and unconditioned attic storage.

8 8 Chapter 1: Overview of Energy Efficient Construction Figure 1-4 shows a two-story home cross-section with a vented crawl space, insulated floor and unconditioned attic storage. The HVAC system must be in a conditioned space. In this example, because the ceiling is insulated, the HVAC is located on the first floor. This design requires the use of floor trusses on the second floor for the duct system and utilizes the crawl space for the first floor duct system. Because the first floor ducts are not within the building envelope, it is important that they be insulated and sealed. Ceiling trusses must be designed to handle the storage load and be high enough to prevent the compression of the insulation. Figure 1 4 Two-story Home Cross-section with a Crawl Space; Attic Storage

9 Chapter 1: Overview of Energy Efficient Construction 9 Figure 1-5 shows a two-story home cross-section with a slab floor. The attic is not used for storage or HVAC. This design is more difficult for a single story home. The HVAC equipment can be located in the insulated envelope of the building; however, keeping the duct system in the envelope takes planning. Recommendations for the design and installation of ducts in unconditioned areas are discussed in Chapter 8. Figure 1 5 Two-story Home Cross-section on a Slab; No Attic Use

Green Remodeling Illustrations GREEN REMODELING ILLUSTRATIONS GREEN BUILDING GUIDELINES FOR HOME REMODELING

Green Remodeling Illustrations GREEN REMODELING ILLUSTRATIONS GREEN BUILDING GUIDELINES FOR HOME REMODELING WWW.STOPWASTE.ORG New Addition Consider the following green remodeling options in a new addition.