DESIGN OBJECTIVES Acce ssib le
Update Building Systems Appropriately
C o st - Ef f e ct ive
by the WBDG Historic Preservation Subcommittee Last updated: 11-21-2010
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Fo r many histo ric structures, "building systems" are new additio ns that must be inco rpo rated with as much sensitivity to Recommendations the o riginal fabric as po ssible. Ho wever, mo re recently Major Resources co nstructed buildings, such as early 20 th century co mmercial buildings, may co ntain early systems that may be histo ric themselves and can be reused. Fo r example, deco rative ventilatio n grilles and switch plates may co ntribute to a building's significance as much as marble wainsco ting o r deco rative stenciling.
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Careful planning is required to balance preservatio n o bjectives with interio r systems, such as HVAC, electrical, plumbing, structural systems, info rmatio n and co mmunicatio n techno lo gies, and co nveyance systems. Since new mechanical and o ther related systems, such as electrical and fire suppressio n, can use up to 10 % o f a building's square fo o tage and 30 %-40 % o f an o verall rehabilitatio n budget, decisio ns must be made in a systematic and co o rdinated manner. While it might no t be always po ssible to co mpletely co nceal the presence o f new techno lo gy, it may be po ssible to lessen the impact o n a building's integrity and retain as much o f the o riginal building fabric as po ssible.
SPAC E T YPES D ESIG N D ISC IPLIN ES PR O D UC T S & SYST EMS
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
Changes—bo th big and small—can have a significant cumulative impact o ver time. Care must be taken during initial pro ject design and perio dic upgrades to avo id the incremental lo ss o f integrity. Fo llo wing are fo ur basic principles to keep in mind when upgrading systems in histo ric pro perties: Sympathetic Upgrades: Building systems upgrades sho uld be sympathetic to the architect's specific design intent, e.g., utilitarian spaces vs. highly finished spaces. Reversibility : Building systems upgrades sho uld be installed to avo id damage to —o r to be remo vable witho ut further damaging—character-defining features and/o r finishes. Retention of Historic Fabric : "Wo rk aro und" the histo ric fabric as much as po ssible. The basic mind-set prescribes fo retho ught and respect fo r histo ric materials. Fo r example, design systems efficiently eno ugh to fit into existing o penings o r be accessible o ff site. Life-Cycle Benefit : Lo ng-term preservatio n emphasizes life-cycle benefits o f reusing histo ric pro perties and planning fo r changing needs . As such, co nsider the fo llo wing: Minimize intrusio ns and lo ng-term impact o n histo ric materials as future repairs and replacements are made. Co mplex systems will require mo re maintenance to perfo rm pro perly. Explo re alternatives that will allo w the reuse o f existing system elements, e.g., reuse ducts to avo id replacement co sts. Design zo ne systems that will allo w repairs to be do ne witho ut disrupting the entire building. Take advantage o f financial benefits o f histo ric pro perties, such as special use rental o r increased rental rates, o f resto ring lo bbies and o ther significant spaces previo usly altered.
Early Planning During the initial design phase, preservatio n zo nes are defined within the individual preservatio n management plan, giving a hierarchy o f significance to the building's spaces and features (i.e., PDFmyURL.com
primary, seco ndary, and tertiary spaces). An understanding o f the building's mo st impo rtant spaces and features is critical to evaluating preservatio n trade-o ffs and preserving characterdefining qualities. It is better to install new equipment in seco ndary o r tertiary spaces, and avo id o r minimize intrusio ns in primary architectural spaces. Basements and attics are usually go o d lo catio ns fo r ho rizo ntal ro uting o f systems; existing chases such as fireplaces, flues, and utility clo sets are go o d fo r vertical ro uting o f systems; and use existing penetratio ns and chases to the greatest extent po ssible. Be aware that so me basements may co ntain valuable archeo lo gical sites that sho uld no t be disturbed. Also , janito rial clo sets can be go o d lo catio ns fo r electrical equipment. Where po ssible, use this o ppo rtunity to impro ve o n the placement and functio n o f a building's systems so as to emphasize the building's integrity. BACK TO TO P
RECOMMENDAT IONS A. HVACâ€”Heat ing, Vent ilat ion, and Air- Condit ioning Cho o se a system and/o r equipment that is appro priate fo r the use o f the building. Fo r instance, a museum has different climatic needs than an o ffice building. General Retain o riginal architectural co nfiguratio ns, surfaces, and finishes, such as vaulted and o rnamental ceilings, pilasters, and capitals. Retain any existing histo rically significant Installation of a dropped ceiling in a historically significant room. Notice the features, such as o riginal registers, radiato rs, detrimental affects to both the scale and escutcheo ns, radiato r enclo sures, etc., by reusing windows of the room. existing ductwo rk, vents/air intakes, and janito rial Photo courtesy National Park Service clo sets. If disturbance is unavo idable, the replacement sho uld match the design, co lo r, texture, and materials o f the o riginal. Match the finished appearance o f the space to the o riginal. Ensure that the additio n o f HVAC systems and o ther repairs will no t co rrupt the building's structural integrity. Distribution System Avo id the need fo r new ductwo rk, especially in lo bbies, co rrido rs, and o ther circulatio n spaces, by examining ductless alternatives such as split systems and pipe systems with reuse o f existing ducts fo r ventilatio n. If new ductwo rk is unavo idable, disturb as little PDFmyURL.com
o riginal fabric as po ssible and minimize the visual impact. Avo id reco nfiguring ceilings (e.g. suspended ceilings) to acco mmo date air distributio n. Install in attic o r basements first. If service areas are no t available, carefully place in seco ndary areas, never in primary spaces, away fro m windo w heads. Retain full windo w height so that exterio r appearance is unaltered. Co nfigure ceilings to avo id o bscuring the full Ductwork retrofit. The insensitively height o f windo ws and interio r o r exterio r installed ductwork detracts from the transo ms. hallway's scale and obscures the Retain deco rative millwo rk and o ther charactertransoms. defining features. Rather than puncturing Photo courtesy National Park deco rative elements, mo ve the po sitio n o f the Service ductwo rk. Co nfigure ductwo rk to be as flat as po ssible and to avo id disrupting the symmetry o f the space. Explo re zo ning using multiple, smaller ducts, rather than a single, larger pro file duct system. Avo id running ductwo rk alo ng o r acro ss co rrido rs. Where appro priate, step, slo pe o r po cket o ut the ceiling with sufficient depth to retain the o riginal appearance o f a full, uno bscured windo w fro m the exterio r. In so me cases, expo sed ductwo rk may be appro priate, such as in industrial o r o ther utilitarian buildings, o r spaces with vaulted o r o ther deco rative ceilings that wo uld o therwise have to be o bscured.
Left: A good example of ductwork installation does not obscure windows or transoms. bad example of ductwork installation obscures either windows or transoms or both. Photos courtesy National Park Service
Building Envelope Retain windo w o perability; install PDFmyURL.com
Retain windo w o perability; install lo cks and/o r sto ps if required to co ntro l tenant use. Use o perable windo ws fo r natural ventilatio n during temperate spring and fall mo nths whenever po ssible. Use weather stripping and insulating do o rs and windo ws, instead o f replacing o r sealing windo ws. Co nsider the architect's o riginal energy co nservatio n metho ds, Former bank building (now a hotel), Minneapolis, such as o perable windo ws, Minnesota. When an exterior wall of a building is 5' or po rches, o verhangs, etc. closer to an adjacent building, fire exposure may come Inco rpo rate these features into from either the inside or the outside of the two buildings. the o verall energy co nservatio n Therefore, fire separation in some form must be plan. provided. In order to retain the window opening, rather Are weather stripping and than infilling to achieve code compliance, a sprinkler sto rm windo ws appro priate? head was installed at the window to ensure proper Retain o riginal ventilatio n safety. systems, (e.g. attic vents, crawl Photos courtesy of the National Park Service space, and airflo w patterns). Carefully co nsider insulatio n o ptio ns; ensure that the cho sen metho d/materials will no t create co ndensatio n in a building's interio r. Co nsider the appro priateness o f mo isture vapo r barriers; if cho sen, install them with sensitivity to the histo ric fabric. Maintain go o d breathability/permeability o f the envelo pe; be mindful o f the o riginal structure's inherent to lerance to mo isture. Equipment Install air handlers and o ther equipment in lo catio ns that will least affect building o ccupants and activities (e.g. vibratio n and no ise). Install wall o r ceiling mo unted equipment in seco ndary o r tertiary spaces. Lo cate any exterio r building equipment adjacent to a seco ndary o r tertiary faรงade o r landscape, rather than the primary faรงade o r landscape. Landscaping is a lo w co st metho d o f camo uflaging new HVAC equipment. Remo tely lo cating new equipment may be necessary if there are archeo lo gical o r histo ric landscape features immediately adjacent to a building. Hide ro o f-mo unted equipment fro m the street o r o ther o bvio us vantage po ints (a site study can indicate go o d lo catio ns). A detailed discussio n o f installing HVAC equipment in histo ric buildings can be fo und in PDFmyURL.com
Preservation Brief 24: Heating, Ventilating, and Cooling Historic Buildings Problems and Recommended Approaches.
B. Inf ormat ion and Communicat ion Technology Info rmatio n techno lo gy systems are co mplex and co nstantly changing. These systems have expo nentially increased the need fo r easily accessible wiring raceways. To day's mo dern o ffice buildings inco rpo rate raised flo o rs that allo w easy access to wiring systems. Altho ugh no t appro priate fo r all buildings and spaces, in so me histo ric buildings this appro ach can enable retentio n o f o rnamental ceilings and features: Co nsider wireless so lutio ns. Reuse existing co nduit and wiring chases to the greatest extent po ssible. Fo r small and/o r highly significant buildings, co nsider lo cating co mputer servers o ff-site. Design fo r flexibility o f layo ut. Install co mputer and IT wiring that can easily be reversed. Ensure that the wiring and asso ciated equipment are easily accessible so that they may be perio dically replaced and updated. Ensure that the additio n o f info rmatio n and co mmunicatio n techno lo gies and o ther repairs will no t co rrupt the building's structural integrity. Computer Rooms Lo cate servers in appro priate climate-co ntro lled tertiary spaces that minimize intrusio n, such as basements o r existing windo wless ro o ms. Avo id altering do o rs and windo ws fo r climate co ntro l. Use existing vertical chases to run IT cables. Fo r security, retro fit existing do o rs in a reversible and co mpatible manner instead o f replacing them. Wiring Distribution Retain deco rative millwo rk and o ther character-defining features. Avo id o bscuring o r altering deco rative co rnice and o ther character-defining features. Fo r o rnamental spaces, co nsider raceways hidden by histo ric co rnices and mo uldings. Do no t install expo sed wiring systems. Create a maintenance plan with strict standards fo r installatio n o f new wiring and equipment. Ensure that co pies o f wiring diagrams are available to building managers and external lo catio ns. Design fo r flexibility and expansio n. Do no t drill marble, parquet, terrazzo , and o ther finished flo o ring. If unavo idable, drill in co rners to minimize impacts and run wiring alo ng basebo ards. Select high-quality, highest speed, and smallest size cabling to minimize the need fo r future intrusive replacements, especially in o rnamentally significant spaces.
C. Light ing/Elect rical Histo ric lighting levels may no t be appro priate fo r current o r planned use o f a histo ric building PDFmyURL.com
and the installatio n o f new lighting systems may be necessary. The lighting levels and equipment sho uld be appro priate to the building's current o r planned use while respecting the o riginal fabric. Interior Lighting Retain as much o riginal fabric as po ssible when installing new systems (i.e., do no t needlessly puncture a deco rative plaster ceiling o r mo lding, when it may be as feasible to relo cate a fixture o r junctio n bo x). Retro fit existing light fixtures with reflecto rs to increase light o utput. Co nserve and rewire existing fixtures and accesso ries. Even if o riginal fixtures will no t be electrified and/o r used, they sho uld be retained and preserved in situ. If o riginal fixtures canno t pro duce the amo unt o f light required, use alternate light so urces fro m remo vable fixtures, such as task lighting and to rchiĂŠres. Inco nspicuo us sco nces o r uno btrusive perimeter ceiling lighting are preferable to eyecatching mo dern fixtures. Preserve and reuse Retain and reuse o riginal, character defining switch plates and historically significant o ther accesso ries. light fixtures. This Use existing electrical chases. rehabilitation project Install new chases within o r behind walls o r vertically in reused the architect's seco ndary o r tertiary spaces. original lighting scheme If using histo rically sensitive replacements that are wired fo r and extant fixtures. mo dern energy lo ads and light o utput. Photos courtesy National Replicas o f o riginal lighting fixtures can be designed to Park Service acco mmo date energy efficiency and multiple light so urces. Inco rpo rate the o riginal light co lo r in new lighting plans. Ensure that the additio n o f interio r lighting systems and o ther repairs will no t co rrupt the building's structural integrity.
Left: Beforeâ€”A dropped ceiling drastically affects the architect's original intent and grand scale of this space. Right: Afterâ€”The removal of the dropped ceiling restored PDFmyURL.com
the architect's intent and has a much more pleasing and commercially desirable impact. Photos courtesy National Park Service
Exterior Lighting Co nsider landscape features when designing exterio r lighting schemes; o utside lighting will have implicatio ns o n landscape design. Co nsider security and accessibility requirements. Mo unt o n existing po les o r structures. Install in no n-intrusive areas and use it to highlight histo ric features o f a building. Use accent lighting as an effective way to highlight architectural features. Use gentle, raking light rather than large spo tlights. Do no t flo o d faรงades with excessive light. If installing exterio r lighting features, such as light po les o r lo wer light so urces, cho o se histo rically appro priate o ptio ns. Ensure that the additio n o f exterio r lighting systems and o ther repairs will no t co rrupt the building's structural integrity.
D. Plumbing Prio r to initiating a plumbing upgrade, it is impo rtant to ascertain whether these traditio nally utilitarian spaces are in fact histo ric and must be preserved. If they are no t histo ric, then rehabilitate them with sensitivity to the surro unding histo ric building materials, finishes, and features. Ho wever, if plumbing elements are histo ric, then take care to preserve them: Retain and preserve histo rically significant co nfiguratio n, layo ut, and plumbing elements, such as bathro o m and kitchen fixtures and features. Some plumbing elements such as this When repairing/replacing existing pipes, do no t radiator are historic. damage adjacent finish materials, such as flo o r Photo courtesy National Park Service and wall tiles. If new pipes must be installed and are visible, they sho uld be lo cated inco nspicuo usly and they sho uld co mplement adjacent finishes. Use existing pipe runs in their o riginal lo catio n. Otherwise, install them in clo sets, service ro o ms, and wall cavities. Avo id primary faรงades and ro o ms if pipes must be affixed to the interio r o r exterio r o f a building. Do no t cut thro ugh character defining features, such as mo ldings, wainsco ting, etc. Ensure that the additio n o f plumbing systems and o ther repairs will no t co rrupt the building's structural integrity. PDFmyURL.com
E. Conveyance Syst ems Elevato rs and escalato rs may also co ntribute to a building's histo ric significance. First ascertain whether these features are histo rically significant: Reuse existing co mpo nents to maximum extent po ssible. Retain o riginal fixtures, features, and materials; many histo rically significant co nveyance systems still retain so me, if no t all, their o riginal elements, particularly finish elements. Examples are o riginal, exo tic wo o d veneers within elevato r cabs and bro nze and brass switch plates, flo o r indicato rs, and handrails. Co mbine co de requirements and preservatio n co ncerns; o ften o riginal features can be slightly mo dified to meet co de requirements. Ensure that the additio n o f co nveyance systems and o ther repairs will no t co rrupt the building's structural integrity.
All or part of a conveyance system may be historic. For instance, this elevator cab has several character defining features, such as exotic wood paneling, elegant moldings, and metal air vents. Photo courtesy National Park Service
F. St ruct ural When updating a building's structure, it is preferable to retain and repair as much o f the o riginal structural system as po ssible. Ho wever, it may be necessary to add an entirely new structural system o r to strengthen the existing system with mo dern inno vatio ns. Fo r instance, a new structural system might be installed to acco mmo date the larger cro wds asso ciated with a museum; whereas o riginally, the building ho used o nly a small family. Also , it's impo rtant to no te that a structural system itself may be histo ric and may require sensitivity when altering o r repairing it. The Bro o klyn Bridge, fo r instance, is an example o f a structural system that is inseparable fro m the aesthetic impact. If structural interventio n is necessary: When structural systems have histo ric architectural significance; develo p creative so lutio ns to meet life/fire safety requirements as well as histo ric preservatio n go als. Ascertain whether the building's structure o r structural co mpo nents are integral to the character-defining features o f the building: retain as much o f the o riginal structural fo rm and features as po ssible. Replicate the o riginal structural system, if necessary. Plan a use fo r the building that do esn't necessitate an augmented structural system. Co nsider the 'physics' o f a pro po sed repair (i.e., will the alteratio n have the same thermal expansio n co efficient as the existing structural system?). Carefully remo ve, catalo gue, and sto re o riginal adjacent features, finishes, and details fo r later re-installatio n. To access the structural system, it may be necessary to remo ve existing finish materials. PDFmyURL.com
Preserve extant features o f histo ric structural systems, such as po st and beam systems and trusses. Sensitively reinfo rce structural systems; sister principle structural co mpo nents rather then replace them. Do cument any structural features that are to o deterio rated to retain. When selectively repairing a structural system, replace missing o r deterio rated materials inkind; examples include replicating cast iro n co lumns. If substitute materials are unavo idable, they sho uld co nvey the same fo rm, design, and o verall visual appearance as the histo ric feature. Use reversible repair and maintenance metho ds, fo r instance, spray in urea-fo rmaldehyde fo am wo uld be inappro priate fo r a histo ric structural system. Ensure that the additio n o f building systems and o ther repairs will no t co rrupt the building's structural integrity.
Structural elements are an inherent part of the architect's intent; determine which parts, if any, of a building's structure are historic and rehabilitate appropriately. Photos courtesy National Park Service BACK TO TO P
MAJOR RESOURCES WBDG Design Objectives Histo ric Preservatio n—Additio nal Reso urces , Histo ric Preservatio n—Apply the Preservatio n Pro cess Successfully, Histo ric Preservatio n—Acco mmo date Life Safety and Security Needs , Pro ductive—Integrate Techno lo gical To o ls, Pro ductive—Design fo r the Changing Wo rkplace
Publicat ions Preservation Brief 24: Heating, Ventilating, and Cooling Historic Buildings Problems and Recommended Approaches Natio nal Park Service. Structural Analysis of Historic Buildings: Restoration, Preservation, and Adaptive Reuse PDFmyURL.com
Applications for Architects and Engineers by J. Stanley Rabun. Structural Aspects of Building Conservation (McGraw-Hill Internatio nal Series in Civil Engineering) by Po ul Beckmann and Ro bert Bo wles. McGraw-Hill Text: March 19 9 5. Structural Repair and Maintenance of Historical Buildings III by C.A. Brebbia and R.J.B. Frewer (Edito r). Co mputatio nal Mechanics:, May 19 9 3. BACK TO TO P
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