Photovoltaic and Solar-Thermal Technologies in Residential Building Codes: Tackling Building Code Requirements to Overcome the Impediments to Applying New Technologies

Research output: NRELTechnical Report


This report describes the building code requirements and impediments to applying photovoltaic (PV) and solar-thermal technologies in residential buildings (one- or two-family dwellings). It reviews six modern model building codes that represent the codes to be adopted by most locations in the coming years: International Residential Code, First Draft (IRC), International Energy Conservation Code(IECC), International Mechanical Code (IMC), International Plumbing Code (IPC), International Fuel Gas Code (IFGC), and National Electrical Code (NEC). The IRC may become the basis for many of the building codes in the United States after it is released in 2000, and it references the other codes that will also likely become applicable at that time. These codes are reviewed as they apply tophotovoltaic systems in buildings and building-integrated photovoltaic systems and to active-solar domestic hot-water and space-heating systems. The first discussion is on general code issues that impact these technologies--for example, solar access and sustainability. Then, secondly, the discussion investigates the relationship of the technologies to the codes, providing examples, while keepingtwo major issues in mind: How do the codes treat these technologies as building components? and Do the IECC and other codes allow reasonable credit for the energy impacts of the technologies? The codes can impact the implementation of the above technologies in several ways: (1) The technology is not mentioned in the codes. It may be an obstacle to implementing the technology, and the solution isto develop appropriate explicit sections or language in the codes. (2) The technology is discussed by the codes, but the language is confusing or ambiguous. The solution is to clarify the language. (3) The technology is discussed in the codes, but the discussion is spread over several sections or different codes. Practitioners may not easily find all of the relevant material that should beconsidered. The solution is to put all relevant information in one section or to more clearly reference relevant sections. (4) The technology is prohibited by the code. Examples of this situation were not found. However, energy credit for some technologies cannot be achieved with the requirements of these codes. Finally, four types of future action are recommended to make the codes reviewed inthis report more accommodating to renewable energy technologies: (1) Include suggested language additions and changes in the codes; (2) Create new code sections that place all of the requirements for a technology in one section of an appropriate code; (3) Apply existing standards, as appropriate, to innovative renewable energy and energy conservation technologies; and (4) Develop new standards,as necessary, to ease code compliance. A synergy may be possible in developing suitable code language changes for both photovoltaic and solar hot-water systems. The installation of rooftop photovoltaic panels and solar hot-water collectors involves many overlapping issues. Roof loading, weather tightness, mounting systems, roof penetrations, and similar concerns are identical for bothtechnologies. If such work can be coordinated, organizations supporting both technologies could work together to implement the appropriate revisions and additions to the codes.
Original languageAmerican English
Number of pages86
StatePublished - 1999

Bibliographical note

Prepared from a longer subcontractor report for the National Renewable Energy Laboratory, entitled 'Renewable Energy and Energy Efficiency Technologies in Residential Building Codes', by David Wortman and Linda Echo-Hawk (September 20, 1998).

NREL Publication Number

  • NREL/TP-550-26579


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