Wiring the Past for the Future
The United States is aging, and its buildings are getting older, too. Because of their association with historic people and events and because they represent unique lifestyles and periods in our nation’s history, interest in preserving these older buildings has increased. Federal, state and local governments; individuals; and other entities, such as the National Trust for Historic Preservation, want to protect unique architecture. Similarly, there is growing interest in preserving building-centric sites where historical events occurred. Adding to this trend is the growing awareness that it may be more economical and environmentally responsible to renovate and repurpose a structurally sound existing building than to demolish it and start over with a new building.
Maintaining the architectural integrity of a historic building
while renovating it to meet current codes and ensuring it functions as a modern building—is a challenge for the design and construction team. However, this challenge is becoming increasingly common, and electrical contractors with expertise in historic preservation may find a new market niche with owners, designers and construction managers engaged in this work. Historic preservation requires innovation and creative solutions to integrate modern power, communications and control systems safely into historic buildings to make them functional for use in the 21st century.
Historic building determination
An old building is not necessarily a historic building no matter its age. The definition and criteria vary for determining whether a building is historic or just old. In general, the qualifying criteria follow the federal government’s lead, and the National Park Service uses it for listing buildings on the National Register of Historic Places (NRHP). To list a building on the NRHP, it must be at least 50 years old, and it must look as it did during the period of interest. In addition, the building should be architecturally significant and/or associated with important historic or cultural events or a part of the lives of historically significant people.
Having a building that is listed on the NRHP or recognized as contributing to a historic district is very important to building owners because it is a prerequisite to qualify for the federal tax credit that is given for renovating a historic building. Similarly, the criteria imposed by state or local governments and other entities are often prerequisites for qualifying for their tax incentives and grants.
Building codes and historic buildings
Building codes are written primarily for new construction or the renovation of existing buildings that do not have historic significance. These types of existing buildings can be modified without regard to preserving the original architecture. Building codes are constantly evolving and improving as the building industry gains more experience in the protection of life and property from fires, natural disasters and building failures. This learning process is a very important part of code development. However, the evolution of building codes can conflict with historic building preservation; the latter’s goal is to faithfully restore and preserve the building as it was at a time when building codes were either nonexistent or not as comprehensive as they are today.
Many building codes
in the United States are prescriptive, such as the National Electrical Code (NEC), and specify the minimum requirements that must be met for an installation. However, many of these prescriptive codes also include a provision that allows for the use of alternative methods that meet the intent of the building code when approved by the authority having jurisdiction (AHJ). In the 2011 edition of the NEC, alternative methods are allowed in Section 90.4 by “special permission,” where it is ensured that equivalent objectives can be achieved by establishing and maintaining effective safety. Article 100 defines the term “special permission” as the written consent of the AHJ. The provision that allows the use of alternative methods acceptable to the AHJ in lieu of the prescriptive code requirements can be vital to the success of a historic preservation project.
Recognizing the need to maintain the architectural integrity of historic buildings
while not compromising public protection, the need to promote sustainability and energy efficiency, or disabled accessibility—government entities have either developed or adopted building codes that address the unique challenges associated with historic buildings. For example, California has the State Historical Building Code (SHBC), which provides alternative requirements for the rehabilitation, preservation, restoration or relocation of structures that are designated historic buildings. The 2010 edition of the SHBC can be found on the California Department of General Services’ website at www.dgs.ca.gov; Section 8-904 covers electrical systems.
more states, counties and municipalities are developing or adopting codes for the renovation of existing buildings that often specifically address historical buildings. The International Existing Building Code (IEBC) is a model code promulgated by the International Code Council (ICC) as part of its building code series; the latest is the 2012 edition. The purpose of the IEBC is to encourage the continued use of existing buildings, including historic buildings. The objective of the IEBC is to maintain public safety without requiring full compliance with the new construction requirements of its other model codes. The IEBC is available through the ICC website at www.iccsafe.org.
At the federal level, about one-fourth of buildings owned by the U.S. General Services Administration (GSA) are either listed or eligible for listing on the NRHP and include residences, courthouses, post offices, office buildings and other structures. The GSA is dedicated to preserving the architecture of these historic buildings and provides an extensive library of resources that include guidelines, standards, and procedures for renovating and maintaining these historic buildings. These resources can be found on the GSA’s website at www.gsa.gov.
When undertaking a historic building project, the electrical contractor needs to be aware of the applicable building codes and the respective editions of the codes that apply to the project. Increasingly, local, state, and federal government entities want to encourage the continued use of existing buildings and the preservation of historic buildings. As a result, these government entities are modifying new construction building codes, developing their own existing building code, or adopting a model code such as the IEBC. Even if a project does not come under an existing or historic building code, the electrical contractor should be familiar with the codes and other resources discussed in this section because it may help formulate alternative methods for achieving the project’s preservation objectives that are acceptable to the AHJ.
Historic building boundaries
There is a misconception that historic buildings must be restored in their totality with all areas being faithfully returned to their original look and use. This is only the case when a property is being renovated to be used as a museum. Most often, only portions of a historic building are required to be restored to its original look, leaving other features and areas of the building to be upgraded and modified as required for changes in occupancy and use. Many times, it is just the building’s exterior, roof and surrounding area that need to be restored and maintained as historically accurate. In fact, it may just be that the portion of the building facade readily visible to the passing public from surrounding streets and walkways that needs to be maintained in its original form, and more leeway may be allowed for the portion of the roof and other facades away from the public eye. For example, a flat roof with a surrounding parapet may allow the electrical contractor to install a photovoltaic array on a historic building that would contribute to its energy efficiency but would not affect its architectural integrity.
Similarly, interior corridors, stairways, elevator cores and certain common areas open to the public may need to maintain their historical look, while other rooms that have specific functions (such as offices, classrooms and laboratories) may be allowed greater flexibility in layout and appearance, so they can be updated and used effectively. These interior common areas may present a challenge to the electrical contractor in terms of emergency lighting and exit signage. This is where the electrical contractor’s ingenuity may come into play, allowing it to meet the intent of codes without compromising the architectural look of the space. Self luminous exit signs that meet the requirements of Section 7.10 of NFPA 101, Life Safety Code, could be installed along egress paths on what appears to be portable furnishings that are, in fact, permanently fixed in place and not movable. Similarly, general lighting could be used for emergency lighting by installing an uninterruptible power supply on the lighting branch circuit as allowed by NEC 700.12(C).
Technology and historic buildings
Where it is not possible to install conventional power, communications and control devices, equipment or systems in or on a historic building, technology may provide the answer. Wireless communications and control systems are available for just about every need. Bluetooth- and Wi-Fi-enabled devices can be used for wireless voice, data and video communications. Similarly, monitoring and control of lighting, electrical and mechanical systems can be accomplished using ZigBee-enabled devices, and fire alarm and security systems can also be unobtrusive, using other highly secure and reliable radio frequency technologies. Wireless devices can be more easily placed to reduce visual impact on a building surface than wired devices, because the location of a wired device will be dictated by where the wire can be brought through the building surface.
In addition to wireless solutions
the availability of low-voltage power and control systems that are listed as Class 2 power-limited systems and comply with Part III of NEC Article 725 is increasing. These systems typically use small-gauge multi-conductor cables that do not require raceway if the proper cable type is used. These systems are safe from both fire and shock and are easier to install in historic buildings than conventional systems.
Options now abound to keep historic buildings functional, preserving the past while setting up the future.