Update Building Systems Appropriately Whole Building Design Guide

Update Building Systems Appropriately

by the WBDG Historic Preservation Subcommittee

Last updated: 09-16-2014

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For many historic structures, building systems are new additions that must be incorporated with as much sensitivity to the original fabric as possible.

Careful planning is required to balance preservation objectives with interior systems, such as HVAC. electrical, plumbing, structural systems, information and communication technologies, and conveyance systems. Since new mechanical and other related systems, such as electrical and fire suppression, can use up to 10% of a building’s square footage and 30%40% of an overall rehabilitation budget, decisions must be made in a systematic and coordinated manner. While it might not be possible to always completely conceal the presence of new technology, it may be possible to lessen the impact on a building’s integrity and retain as much of the original building fabric as possible.

Exposed spiral ductwork is appropriate in this industrial interior. This treatment is not appropriate in more finished interiors, where plaster covers walls and ceilings.

(Photo courtesy of the National Park Service.)

However, more recently constructed buildings, such as early 20th century commercial buildings, may contain early systems that may be historic themselves and can be reused. For example, decorative ventilation grilles and switch plates may contribute to a building’s significance as much as marble wainscoting or decorative stenciling.

The interior character of a historic building should be respected when installing new systems. For example, in a finished interiori.e. one with plaster on the walls and ceilings, such as a house, office building, hotel or apartment buildingnew systems and ductwork should be concealed in attics or basements, or placed in boxed soffits. In industrial interiorsi.e. a warehouse or factorythese features may be exposed.

Apartment Building, Washington, DC (late 1920’s). Beam slightly elongated to accommodate sprinkler pipes and other systems in a highly ornate residential apartment building. (Photo courtesy of the National Park Service)

Changesboth big and smallcan have a significant cumulative impact over time. Care must be taken during initial project design and periodic upgrades to avoid the incremental loss of integrity. Following are four basic principles to keep in mind when upgrading systems in historic properties:

  • Sympathetic Upgrades. Building systems upgrades should be sympathetic to the architect’s specific design intent, e.g. utilitarian spaces vs. highly finished spaces.
  • Update Building Systems Appropriately Whole Building Design Guide
  • Reversibility. Building systems upgrades should be installed to avoid damage to or to be removable without further damagingcharacter-defining features and/or finishes.
  • Retention of Historic Fabric. «Work around» the historic fabric as much as possible. The basic mind-set prescribes forethought and respect for historic materials. For example, design systems efficiently enough to fit into existing openings or be accessible off site.
  • Life-Cycle Benefit. Long-term preservation emphasizes life-cycle benefits of reusing historic properties and planning for changing needs. As such, consider the following:
    • Minimize intrusions and long-term impact on historic materials as future repairs and replacements are made.
    • Complex systems will require more maintenance to perform properly.
    • Explore alternatives that will allow the reuse of existing system elements, e.g. reuse ducts to avoid replacement costs.
    • Design zone systems that will allow repairs to be done without disrupting the entire building.
    • Take advantage of financial benefits of historic properties, such as special use rental or increased rental rates, of restoring lobbies and other significant spaces previously altered.

Early Planning

During the initial design phase, preservation zones are defined within the individual preservation management plan. giving a hierarchy of significance to the building’s spaces and features (i.e. primary, secondary, and tertiary spaces). An understanding of the building’s most important spaces and features is critical to evaluating preservation trade-offs and preserving character-defining qualities. It is better to install new equipment in secondary or tertiary spaces, and avoid or minimize intrusions in primary architectural spaces. Basements and attics are usually good locations for horizontal routing of systems; existing chases such as fireplaces, flues, and utility closets are good for vertical routing of systems; and use existing penetrations and chases to the greatest extent possible. Also, janitorial closets can be good locations for electrical equipment. Where possible, use this opportunity to improve on the placement and function of a building’s systems so as to emphasize the building’s integrity.

Be aware that some basements may themselves be historically significant because of prior use, storage, or other factors, not necessarily related specifically to the building containing the basement. Also basements excavated prior to the NHPA might have intruded into significant archaeological sites, so ground disturbances due to new utility trenches, exterior waterproofing, installing French drains, etc. must be subject to Section 106 consultations, either as part of the building undertaking or as separate undertakings.


A. HVACHeating, Ventilation, and Air-Conditioning

Choose a system and/or equipment that is appropriate for the use of the building. For instance, a museum has different climatic needs than an office building.

To preserve the distinctive decorative pressed-tin ceiling on the interior of this finished late 19th-century commercial building, spiral duct work was left exposed. This approach was taken because in this instance, it would be more intrusive to add a boxed soffit. The exposed duct was painted the color of the walls to lessen its impact. Depending on the circumstances, painting the duct the color of the ceiling may work as well. It was also placed at the perimeter of the room, so the important open retail space was not subdivided, and was installed close to the ceiling, so this new feature does not appear more prominent as it hangs down. This solution meets the Secretary’s Standards. (Photos by Audrey Tepper)

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