2012 National Green Building Standard Commentary

By Association of National

This companion to the ANSI-approved 2012 National Green Building Standard provides valuable insight to the intention and implementation of the practices and provisions found in the Standard. This Commentary is a useful resource for residential designers, land developers, builders and remodelers using the Standard as a tool for developing or renovating residential properties of all types to reduce their relative environmental impact. The Commentary expands on the compliance language in the Standard, including:? Scope and Administration? Compliance Method for all applications of the Standard: Single family and multifamily new construction Renovation and addition chapters include whole-house renovations and functional areas Green subdivision development? Requirements and prescriptions for all chapters within the Standard: Site design and development Lot design, preparation, and development Resource Efficiency Energy efficiency Water efficiency Indoor environmental qualityThis latest edition incorporates all changes made to the 2012 Standard and is a valuable tool to assist in the design, construction and compliance of any sustainable residential project.

• Language: English
• Publisher: BuilderBooks
• Release date: Jan 1, 2014
• ISBN: 9780867187281

Book preview

Entity.

CHAPTER 1. SCOPE AND ADMINISTRATION

101 GENERAL

The provisions of the NGBS apply to all types of residential construction inclusive of the building, site, lot, and accessory structures. Where only a part of the building is for residential use (mixed-use buildings), the NGBS applies only to the residential portion(s) of the building. (See Section 304 for additional guidance.) The NGBS applies to new residential construction projects and renovation of existing residential buildings, including historic buildings. The renovation provisions apply to all types of residential buildings including multi-unit buildings and residential portions of mixed-use buildings. The NGBS does not provide specific provisions for renovation of accessory structures. Therefore, renovation of an existing accessory structure has to result in a structure that complies with applicable provisions for new construction to achieve compliance with the NGBS.

The building’s occupancy is established in accordance with the governing local building code. Where the ICC family of building codes is adopted, chapter 3 of the International Building Code (IBC) is used to establish the occupancy category. All four types of residential occupancies addressed in the IBC are included in the scope of the NGBS: R1, R2, R3, and R4. Residential occupancies include buildings where the occupants are transient in nature (e.g., hotels) and buildings where the occupants are primarily permanent in nature (e.g., apartment buildings). The scope of the NGBS also includes one- and two-family dwellings as defined in the International Residential Code (IRC). Buildings or portions thereof classified as institutional are not included in the residential occupancy and cannot seek compliance under the NGBS. Section 508 of the IBC provides additional requirements for mixed-use buildings, including provisions for height, allowable area, separation, incidental uses, etc.

The NGBS and its criteria are also applicable to subdivisions and building sites intended for the eventual construction of buildings or additions thereto classified as residential occupancy. The terms subdivision, site, and lot are defined in chapter 2 of the NGBS. The terms subdivision and site are used interchangeably in the context of chapters 3 and 4 of the NGBS and apply to the compliance method for green subdivisions covered in Section 302. The term lot applies to the chapter 5 land development practices included in the compliance method of Section 303 for green buildings.

The NGBS and its criteria further apply to alternations, additions, and renovations of existing single-family and multifamily residential buildings. Renovation is the more encompassing term and includes the process for restoring or improving an existing building or dwelling unit that may include changes to the landscape. The term alternation covers any construction and renovation to an existing structure that requires a permit. Alternations do not include additions. The term addition refers to an extension or increase in the floor area or height of a building or structure. The NGBS is applicable to all of these types of construction activities.

The NGBS establishes criteria for rating the reduction of environmental impact and the related performance improvements expected from implementing environmentally preferable design and construction practices. The criteria is expressed in terms of points assigned to individual green building practices and the minimum point thresholds required to achieve one of the four performance levels. (Refer to the chapter 3 commentary for additional information on the compliance method.) In addition, the NGBS assigns mandatory status to practices viewed as essential to the green building designation. All mandatory and optional practices are grouped into seven universally recognized green building categories, which are organized by chapters in the NGBS. These include:

Chapter 4 – Site Design and Development

Chapter 5 – Lot Design, Preparation, and Development

Chapter 6 – Resource Efficiency

Chapter 7 – Energy Efficiency

Chapter 8 – Water Efficiency

Chapter 9 – Indoor Environmental Quality

Chapter 10 – Operation, Maintenance, and Building Owner Education

These green building categories are aligned with the primary guiding principles driving any green building project. Each category is associated with its own specific intent that serves the overall green building goals of reduced impact on nature’s resources by providing:

Land development practices that preserve and restore site features to the extent possible while reducing the effects of storm water runoff and enhancing the performance of buildings

Design and construction practices that result in resourcing efficient building systems, minimizing material waste, and improving durability of materials and systems

Building technologies and design techniques that aim at reducing the energy and water consumption needed to operate the building

Materials and design features that improve the quality of the indoor environment

Educational and operational resources that help owners and occupants achieve optimum long-term building performance

Where appropriate, the NGBS and this commentary include focused intent statements to provide additional insight into the basis for the green building practices.

Because new green building techniques and technologies are emerging at a rapid pace, the NGBS recognizes that flexibility is needed to permit innovative approaches and techniques not specifically enumerated by the provisions. Therefore, where warranted and consistent with the intent of the NGBS, the Adopting Entity (see Section 103) may award points to encourage the recognition of such technologies. The implementation of this guiding principle is further explained in Section 102.4 Alternative Compliance Methods and Section 301.2 Awarding Points.

Practices selected from the NGBS must not violate the provisions of statutes and regulations governing construction of a given project in a given jurisdiction. The NGBS is intended to provide a method for improving a project’s environmental performance beyond typical minimum practices or minimum code requirements. However, inclusion of materials or practices in the NGBS does not infer local code acceptability. It is therefore the responsibility of the building designer to ensure compliance with all applicable regulations.

Referenced documents are included in the provisions of the NGBS to provide additional criteria for compliance with prescribed measures and, in some cases, to provide alternative compliance criteria and methods (e.g., ENERGY STAR for homes as an alternative compliance for bronze-level energy requirements). All applicable requirements of the reference document must be met in order to demonstrate compliance with a mandatory provision of the NGBS or to receive points for a non-mandatory practice. Where a provision of the NGBS refers to a part of a specification, standard, or code, compliance with that specific part of the reference document is sufficient to meet that provision. Where a provision of the NGBS refers to a referenced document in its entirety, all of the relevant criteria of that document must be met to achieve compliance with that provision. The NGBS references the specific version/year of the document as listed in chapter 13. New editions of referenced documents do not supersede the referenced documents for the purpose of complying with the NGBS.

The 2012 NGBS includes five appendices:

Appendix A – Ducted Garage Exhaust Fan Sizing Criteria (referenced in Section 901.3(1)(c) of the NGBS);

Appendix B – Whole Building Ventilation System Specifications (referenced in Section 902.2.1 of the NGBS);

Appendix C – Climate Zones

Appendix D – Examples of Third-Party Programs for Indoor Environmental Quality

Appendix E – Accessory Structures

Appendices A and B are part of the NGBS and contain design information for mechanical systems. To qualify for points under Sections 901.3(1)(c) and 902.2.1 of the NGBS, the design of the applicable mechanical systems must comply with the criteria of the corresponding appendices. Both appendices are extracted from ASHRAE Standard 62.2-2007 and are included with the NGBS to facilitate the design process.

To facilitate the application of the practices that depend on the climate zone of the construction site location, appendix C provides climate zone designations by state, county, and territory. The climate zone designations are consistent with those published by the ICC. Appendix C is part of the NGBS.

Appendix D provides a list of third-party certification programs that meet the intent of the NGBS for several practices in chapter 9 addressing source emission control. Appendix D is not part of the NGBS, and the listed programs are only examples of compliant programs. This list is not intended to be comprehensive. Because the updated NGBS includes substantial revisions to the third-party credentialing requirements, the consensus committee decided to provide this complimentary list to help users with interpretation and application of the new provisions. Other programs that are not listed in the appendix but comply with the requirements of the provisions can be used to achieve compliance with the applicable practices.

Appendix E provides compliance criteria for accessory structures. It is not the intent of the NGBS to require compliance for accessory structures in order to achieve compliance for the primary building. The user should refer to Section 306.2 of the NGBS. Appendix E is part of the NGBS only if specifically adopted by the Adopting Entity. Based on the compliance rules setup by the Adopting Entity, compliance with appendix E can be voluntary or mandatory. The intent for including provisions for accessory structures was to align the scope of the NGBS with the scope of minimum green building codes (e.g., International Green Construction Code, local green codes) where the NGBS is or can be referenced. Separating the provisions for accessory structures into a standalone appendix provides a wide degree of flexibility for the adopting entity with regard to establishing compliance rules based on the market preferences and requirements of locally adopted minimum building codes.

102 CONFORMANCE

The NGBS is a rating system, which provides a menu of options for achieving a specified rating level expressed in terms of a minimum number of points. In addition to the minimum point thresholds, the NGBS designates select practices as mandatory. These practices are viewed as essential and universal for any project seeking a green rating (i.e., without these practices a home could be not considered green in the view of the consensus committee). Combining mandatory provisions with a point system provides the users with flexibility in selecting construction technologies appropriate for their projects, markets, and customers. All applicable mandatory practices must be implemented to qualify for any performance level of the NGBS. Certain practices in the NGBS are mandatory only at higher rating levels (e.g., Section 801.5). (Refer to the commentary in chapter 3 for additional information on the compliance method and mandatory practices.)

The NGBS is written in language conducive to implementation in design and construction and, as appropriate, verification of compliance. Chapters 1, 2, and 3 provide framework for the entire NGBS and are mandatory as reflected by use of the term shall. To comply with the NGBS, a project must satisfy all applicable provisions of chapters 1, 2, and 3. The practices in chapters 4–11 are mandatory only if the user claims the associated points toward a rating level or the practice is designated as mandatory. The practices in chapter 12 are mandatory as applicable to the scope of the specific remodeling activity as defined in that section. In those chapters, the practices use various forms of to be.

In accordance with Section 103, administration of the NGBS is within the purview of the Adopting Entity. The Adopting Entity establishes an applicable verification protocol, including requirements for the documentation of compliance with the provisions and practices of the NGBS. The intent of this section is to provide flexibility for the Adopting Entity and the individual responsible for documentation in determining the type and method of compliance verification; the required documentation does not need to be excessive and should not create an unnecessary burden on the user or the Adoption Entity.

Section 103.3 of the NGBS provides a list of documents that the Adopting Entity may use for verification of compliance. In many cases, documentation that substantially verifies compliance with applicable green building practices may be provided by reference to common construction documents (e.g., plans and specifications listing products, written certifications by the builder indicating compliance with the specified practice). Additional methods acceptable for adequately demonstrating compliance include product specifications, manufacturers’ information, proof of purchase, and a wide variety of other documents.

Where third-party certifications or accreditations are required by a practice to qualify for points, applicable certificates verifying conformance should be provided (e.g., Section 901.6(2)). Some practices in the NGBS specify the documentation required to qualify for points (e.g., Section 702.2 requires documentation of the energy cost performance analysis).

The NGBS allows the Adopting Entity to recognize practices not explicitly listed in the NGBS. Section 301.2(3) establishes rules for assigning points to innovative products and practices.

An alternative practice should meet the intent of another practice already listed in the NGBS or a broader intent of one of the chapters. It is not the intent of this provision to allow adoption of practices that provide a benefit not currently recognized by the NGBS. For example, sound control is not currently recognized by the NGBS as a green feature and does not fall under the alternative compliance clause.

The Adopting Entity should establish a formal process for evaluating the suitability, applicability, and compliance of a proposed alternative practice with respect to the intent of the NGBS and the assignment of appropriate points.

103 ADMINISTRATION

This section requires the Adopting Entity involved in administration of the NGBS to establish a verification process to validate claims of compliance to the specified rating levels.

According to the definition in chapter 2, Adopting Entity is the government jurisdiction, green building program, or any other third-party compliance assurance body that adopts this standard, and is responsible for implementation and administration of the practices herein.

The NGBS does not provide specific criteria for establishing a verification process. However, the framework for verification processes that are part of product certification services and building inspection procedures is well established in the construction industry. These processes follow accepted industry standards and typically include all or several of the following elements:

Criteria for maintaining independent third-party status

Review of design

Review of construction documentation

Review of performance data provided by other third parties in support of compliance claims

Inspections

Documentation of the review and inspection results

Educational requirements for inspectors/verifiers

Internal third-party procedures to ensure data quality and integrity

Procedure for awarding certification of compliance

Ongoing monitoring and continual improvement (e.g., continuing education of inspectors, audits of inspectors, internal reviews)

Oversight (e.g., by an accreditation agency)

The Adopting Entity may perform all third-party functions with in-house staff, or it can have an arrangement with other independent organizations and/or individuals to provide some of the services.

The NGBS certification program administered by the Home Innovation Research Labs is an example of a national program designed to meet the provisions of Section 103. Home Innovation serves as an Adopting Entity for the NGBS and establishes specific rules and procedures for demonstrating compliance. More information on the Home Innovation’s verification program can be found at www.homeinnovation.com/green.

CHAPTER 2. DEFINITIONS

This chapter provides definitions for terms used in the NGBS and establishes requirements for the use of terms defined and not defined in the NGBS. Where applicable, definitions in the NGBS were harmonized with the definitions in the 2009 International Code Family published by the International Code Council. All definitions from chapter 2 of the NGBS are duplicated below to facilitate the use of this commentary.

201 GENERAL

Unless otherwise expressly stated, the following words and terms shall, for the purposes of the NGBS, have the meanings shown in this chapter.

Words used in the present tense include the future; words stated in the masculine gender include the feminine and neuter; the singular number includes the plural and the plural, the singular.

Where terms are not defined in the NGBS, and such terms are used in relation to the reference of another document, those terms shall have the definition in that document.

Where terms are not defined through the methods authorized by this section, such terms shall have ordinarily accepted meanings as the context implies.

202 DEFINITIONS

ACCESSORY STRUCTURE. A structure, the use of which is customarily accessory to and incidental to that of the residential building; the structure is located on the same lot or site as the residential building; the structure does not contain a dwelling unit; and (1) is classified as Group U – Utility and Miscellaneous in accordance with the ICC International Building Code, or (2) is classified as accessory in accordance with the ICC International Residential Code, or (3) is classified as accessory to the residential use by a determination of the Adopting Entity.

ADDITION. An extension or increase in the floor area or height of a building or structure.

ADOPTING ENTITY. The governmental jurisdiction, green building program, or any other third-party compliance assurance body that adopts this standard and is responsible for implementation and administration of the practices herein.

ADVANCED FRAMING. Code compliant layout, framing, and engineering techniques that minimize the amount of framing products used and waste generated to construct a building while maintaining the structural integrity of the building.

AFUE (Annual Fuel Utilization Efficiency). The ratio of annual output energy to annual input energy, which includes any non-heating season pilot input loss, and for gas or oil-fired furnaces or boilers, does not include electrical energy.

AIR BARRIER. Material(s) assembled and joined together to provide a barrier to air leakage through the building envelope. An air barrier may be a single material or a combination of materials.

AIR HANDLER. A blower or fan used for the purpose of distributing supply air to a room, space, or area.

AIR INFILTRATION. The uncontrolled inward air leakage into a building caused by the pressure effects of wind or the effect of differences in the indoor and outdoor air density or both.

AIR MAKE-UP. Air that is provided to replace air being exhausted.

ARCHITECTURAL COATINGS. A material applied onto or impregnated into a substrate for protective, decorative, or functional purposes. Such materials include, but are not limited to, primers, paints, varnishes, sealers, and stains. An architectural coating is a material applied to stationary structures or their appurtenances at the site of installation. Coatings applied in shop applications, sealants, and adhesives are not considered architectural coatings.

BIOBASED PRODUCT. A commercial or industrial product used in site development or building construction that is composed, in whole or in significant part, of biological products, renewable agricultural materials, including plant, animal, and marine materials, or forestry materials.

BROWNFIELD (also EPA-Recognized Brownfield). Real property, the expansion, redevelopment, or reuse that may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant, and includes Brownfield site as defined in Public Law 107-118 (H.R. 2869) – Small Business Liability Relief and Brownfields Revitalization Act (i.e., Pub.L. 107-118, § 1, Jan. 11, 2002, 115 Stat. 2356, provided that: This Act [enacting 42 U.S.C.A. § 9628, amending this section, 42 U.S.C.A. § 9604, 42 U.S.C.A. § 9605, 42 U.S.C.A. § 9607, and 42 U.S.C.A. § 9622, and enacting provisions set out as notes under this section and 42 U.S.C.A. § 9607] may be cited as the ‘Small Business Liability Relief and Brownfields Revitalization Act.’)

CERTIFIED GEOTHERMAL SERVICE CONTRACTOR. A person who has a current certification from the International Ground Source Heat Pump Association as an installer of ground source heat pump systems or as otherwise approved by the Adopting Entity.

CLIMATE ZONE. Climate zones are determined based on Figure 6(1).

CLUSTER DEVELOPMENT. A design technique that concentrates residential buildings and related infrastructure at a higher density within specified areas on a site. The remaining land on the site can then be used for low intensity uses such as recreation, common open space, farmland, or the preservation of historical sites and environmentally sensitive areas.

COGENERATION. An energy process that consecutively generates useful thermal and electric energy from the same fuel source.

COMMON AREA(S).

Areas within a site or lot that are predominantly open spaces and consist of non-residential structures, landscaping, recreational facilities, roadways, and walkways, which are owned and maintained by an incorporated or chartered entity such as a home owner’s association or governmental jurisdiction; or

Areas of a multi-unit building that are outside the boundaries of a dwelling unit and are shared among or serve the dwelling units, including, but not limited to, hallways, amenity and resident services areas, parking areas, property management offices, mechanical rooms, and laundry rooms.

COMPOST FACILITY. An outdoor bin or similar structure designed for the decomposition of organic materials, such as leaves, twigs, grass clippings, and vegetative food waste.

CONDITIONED SPACE. An area or room within a building being heated or cooled, containing non-insulated ducts, or with a fixed opening directly into an adjacent conditioned space.

CONSTRUCTED WETLAND. An artificial wetland system such as a marsh or swamp created as a new and/or restored habitat for native wetland plant and wildlife communities as well as to provide and/or restore wetland functions to the area. Constructed wetlands are often created as compensatory mitigation for ecological disturbances that result in a loss of natural wetlands from (1) anthropogenic discharge for wastewater, storm water runoff, or sewage treatment; (2) mines or refineries; or (3) the development.

CONSTRUCTION WASTE MANAGEMENT PLAN. A system of measures designed to reduce, reuse, and recycle the waste generated during construction and to properly dispose of the remaining waste.

CONTINUOUS PHYSICAL FOUNDATION TERMITE BARRIER. An uninterrupted, non-chemical method of preventing ground termite infestation (e.g., aggregate barriers, stainless steel mesh, flashing, or plastic barriers).

COP (Coefficient of Performance). A measure of the heating efficiency of ground and air-source heat pumps defined as the ratio of the rate of heat provided by the heat pump to the rate of energy input, in consistent units, for a complete heat pump under defined operating conditions. (See EER as a measure of the cooling efficiency of heat pumps.)

DEMAND CONTROLLED HOT WATER LOOP. A hot water circulation (supply and return) loop with a pump that runs on demand when triggered by a user-activated switch or motion-activated sensor.

DESUPERHEATER. An auxiliary heat exchanger that uses superheated gases from an air conditioner’s or heat pump’s vapor-compression cycle to heat water.

DIRECT-VENT APPLIANCE. A fuel-burning appliance with a sealed combustion system that draws all air for combustion from the outside atmosphere and discharges all flue gases to the outside atmosphere.

DRAIN-WATER HEAT RECOVERY. A system to recapture the heat energy in drain water and use it to preheat cold water entering the water heater or other water fixtures.

DURABILITY. The ability of a building or any of its components to perform its required functions in its service environment over a period of time without unforeseen cost for maintenance or repair.

DWELLING UNIT. A single unit providing complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation.

EER (Energy Efficiency Ratio). A measure of the instantaneous energy efficiency of electric air conditioning defined as the ratio of net equipment cooling capacity in Btu/h to total rate of electric input in watts under designated operating conditions. When consistent units are used, this ratio becomes equal to COP. (See also COP.)

ENERGY MANAGEMENT CONTROL SYSTEM. An integrated computerized control system that is intended to operate the heating, cooling, ventilation, lighting, water heating, and/or other energy-consuming appliances and/or devices for a building in order to reduce energy consumption. Also known as Building Automation Control (BAC) or Building Management Control System (BMCS).

ENERGY MONITORING DEVICE. A device installed within a building or dwelling unit that can provide near real-time data on whole building or dwelling unit energy consumption.

ENGINEERED WOOD PRODUCTS. Products that are made by combining wood strand, veneers, lumber, or other wood fibers with adhesive or connectors to make a larger composite structure.

ENVIRONMENTAL IMPACT. See LCA (Life Cycle Analysis/Assessment).

ENVIRONMENTALLY SENSITIVE AREAS.

Areas within wetlands as defined by federal, state, or local regulations;

Areas of steep slopes;

Prime Farmland as defined by the U.S. Department of Agriculture;

Areas of critical habitat for any federal or state threatened or endangered species;

Areas defined by state or local jurisdiction as environmentally sensitive.

EROSION CONTROLS. Measures that prevent soil from being removed by wind, water, ice, or other disturbances.

EXISTING BUILDING. Building completed and occupied prior to any renovation considered under this standard.

EXISTING SUBDIVISION. An area of land, defined as site in this chapter, that has received all development approvals and has been platted and all infrastructure is complete at time of