Sustainable Historic Preservation

by the WBDG Historic Preservation Subcommittee

Last updated: 08-25-2009

Introduction

Historic buildings are inherently sustainable. Preservation maximizes the use of existing materials and infrastructure, reduces waste, and preserves the historic character of older towns and cities. The energy embedded in an existing building can be 39% of the embedded energy of maintenance and operations for the entire life of the building. Sustainability begins with preservation.

Historic buildings were traditionally designed with many sustainable features that responded to climate and site. When effectively restored and reused, these features can bring about substantial energy savings. Taking into account historic buildings' original climatic adaptations, today's sustainable technology can supplement inherent sustainable features without compromising unique historic character.

Preservation keeps our nation's history and culture alive and we learn much from the methods and practices of those who came before us. With our threatened environment, it is imperative that we make sustainable living a part of our lives. The public benefits of both preservation and sustainability are very clear and there is no reason why these goals cannot work together. Revising the current version of LEED to better account for the social values and environmental benefits of preserving historic structures is a good start. The discussion, however, must continue to engage the preservation, sustainability, and construction communities to assure the best possible outcome.

Description

Preserving a building is often called the ultimate recycling project, yet preservationists commonly fight the stigma that historic buildings are inefficient and require daunting corrective measures to retrofit for energy saving devices and systems. Green and sustainable design has become an increasingly popular issue in both the preservation and new construction industries. Preservation and green goals overlap, and reconciling their differences is possible, provided that both sides strive to be as creative and flexible as possible.

The LEED for Neighborhood Development Rating System (LEED-ND) integrates the principles of smart growth, new urbanism, and green building into the first national system for smart, green, and healthy neighborhood design. LEED-ND also addresses historic buildings.

The U.S. Green Building Council recently adopted LEED-EB® as a guideline for greening Existing Buildings. While this is a valuable checklist for maximizing the sustainable qualities of existing buildings in a real estate portfolio, it stops short of addressing historic buildings specifically. This page provides guidance for meeting LEED® and similar sustainability standards in historic building projects. Within the five LEED® categories, the following issues require special attention:

1) Sustainable Sites

Heat Island Reduction

Before the mid 20th century, most parking areas were pervious surfaces often surrounded by trees and covered with gravel to minimize mud problems. Specify low albedo porous paving, such as masonry pavers, reduce heat island effects and create the added benefit of controlling storm water runoff. Where treatment of runoff water is required provide an impervious barrier below a pervious surface to direct runoff to an oil-water separator and/or a treatment facility.

2) Water Efficiency

Reducing water use can negatively impact historic plantings and landscape features. Preserve historic plantings and landscape features by balancing the water goals within the building and site.

Water Use Reduction

Historically, water conservation was a part of daily life. Cisterns collected rainwater and water was reused. Modern gray water recycling systems have evolved from traditional water conservation methods. Specify low flow toilets or consider options similar to historic technology.

'Cultural landscapes' often play central roles in the overall makeup or character of historic properties. They also need water to survive. Therefore, like historic structures, they must be cared for respected, even historic plantings that may not be native species. Efficient irrigation systems may be used to save water, and recycled 'grey' or rainwater may be captured for use in gardens and surrounding landscapes. But restricting water for irrigation to achieve the percentage savings required by LEED may irreparably change the important relationship between a building and its surrounding landscape. Unfortunately, currently there are no provisions within LEED for exempting cultural heritage areas from these calculations.

3) Energy and Atmosphere

Minimum Energy Performance

• Working historic shutters can reduce heat gain significantly. Closing shutters in the morning and opening them in the late afternoon controls heat gain during warm months. In cold months, following the opposite pattern reduces heat loss. This is particularly effective when a building has significant thermal mass.

• Awnings, where historically appropriate, are efficient, and work with the seasonal path of the sun. Properly designed awnings can reduce heat gain by 65% and more.
• In warm climates, make use of existing, deep overhangs to provide shade during the hottest part of the day while allowing sunlight to come in during cold months and cooler parts of the day. Overhangs also keep roof drainage away from building foundations, often negating the need for gutters and downspouts.
• Operable historic windows, louvers, and monitors substantially reduce demand for heating and cooling during temperate months. Educate occupants on effective use of windows. Open the top sash of a double hung window to allow warm air from the top of the room to escape. Open the bottom sash on the shade side of a room to pull in cool air while displacing warm air. It may be possible to maintain the operability of historic transoms over doors to provide cross ventilation in certain situations. However, most fire codes will not allow the use of operable transoms in certain types of facilities because it defeats fire walls and allows smoke/fire to easily migrate from space to space.

• Preserve high ceilings to allow air to circulate and light to enter into a building.
• Courtyards in hot climates traditionally provided shaded outdoor spaces and well-ventilated indoor spaces. Fountains and other water features reduce the energy required to cool these spaces and make courtyards more comfortable during the summer and temperate months. As water condenses, air is cooled. Located in a walled area, cool air is trapped low, providing relief and humidity in hot dry climates. Retain historic open courtyards and water features to achieve these benefits.
• Historic masonry buildings are exceptionally durable and benefit from significant thermal mass. Thermal mass helps regulate the temperature inside by storing heat and cold within the mass of the wall.

Reuse of Historic Windows

LEED fails to acknowledge that historic windows are important features and that their energy efficiency can be upgraded. LEED encourages the use of highly energy efficient windows, which often requires the removal of historic windows that are potentially reusable. Moreover, original windows are character-defining features of historic buildings and their removal can significantly alter a structure's integrity, thus conflicting with preservation goals and the Secretary's Standards.

With property maintenance, windows built from old growth wood can function indefinitely and their performance can be substantially bolstered by using storm windows, caulk, and weather-stripping. Studies have shown that these simple improvements can result in efficiency similar to that of new insulated glass windows. Modern windows also have a relatively short lifespan and can be difficult, if not impossible, to repair. Once modern windows fail, there are few ways they can be recycled, and they will likely end up in landfills. This begins an environmentally insensitive cycle of removal and replacement.

Therefore, the most responsible approach is to retain historic windows that last and retrofit them with increased effectiveness rather than install new windows that, without exception, will fail and cannot be repaired. Regrettably, the replacement window industry is strong, and old windows are touted as poor performers, so the common practice of replacing windows in not likely to change much in the immediate future. To combat this, LEED should consider awarding points for the repair and continued use of old windows where significant improvements in energy efficiency are demonstrated, as well as where significant amounts of historic fabric are being retained and reused.

Specifically, many historic buildings featured hinged, wood storm windows that can be reused. Historic windows were constructed of dense, old growth wood. The life cycle of the majority of modern replacement windows is much shorter. Historic windows can be reused in an energy efficient manner. A traditional single-glazed, double hung window has an R-value of 1, compared to R3 for a new double-glazed, low-e, double hung window. If the historic wall assembly has an R-value in the teens, taking a window from R1 to R3 will not provide sufficient energy savings to offset the cost of replacement windows and associated waste. The primary cause of infiltration can be addressed with jamb insulation, weather stripping, and trim repair. For an extra layer between the occupant and the elements, a storm window can be mounted to the existing window—interior or exterior—with little change to the character of the original unit.

4) Materials and Resources

Source Reduction and Waste Management

Consider use of appropriate salvage historic materials for restoration of lighting, hardware, and other specialty items. Most mid-sized cities have resources for salvaged building materials. Upgrade, rather than replace, historic fixtures.

Optimize Use of IAQ Compliant Products

Early paints and stains featured pigments made from natural plant materials and minerals. Use low volatile organic compounds (VOC) finishes.

Exterior and Interior Materials

While LEED does not yet focus on the value of durable materials in sustainable building, use of durable, renewable natural materials conserves resources in the long-term and is one of the significant sustainable aspects of historic buildings. Consider the embedded energy of existing materials in approaching rehabilitation of interior spaces.

5) Indoor Environmental Quality

Outside Air Introduction and Exhaust Systems

Before the advent of mechanical air conditioning, most historic buildings featured natural ventilation, usually based on the chimney effect. Wherever practical, provide for natural ventilation to maximize efficient air flow, reduce occurrence of sick building syndrome, and increase occupant alertness.

Controllability of Systems: Lighting

Many early offices took advantage of a combination of natural light and task lighting. Retain large window openings and specify low height, directional lamps that illuminate work surfaces effectively. Consider installing sensors to maximize use of natural light by activating ambient electric light only as needed.

Daylighting and Views: Daylighting

Retain tall windows to allow natural light to penetrate a building. With the added benefit of higher ceilings, natural light can travel far into a space. Buildings in a "C" or "E" plan form were common and essentially functioned to facilitate natural light and ventilation. Additionally, skylights provide a flood of natural light, and were often used on the north face of a roof so not to produce glare.

Relevant Codes and Standards

Standards and Guidelines

• Cultural Resource Management Guideline—NPS-28
• Secretary of the Interior's Standards for the Treatment of Historic Properties
• Secretary of the Interior's Standards for the Treatment of Historic Properties with Guidelines for the Treatment of Cultural Landscapes
• Secretary of the Interior's Standards and Guidelines for Archeology and Preservation
• Secretary of the Interior's Standards and Guidelines for Architectural and Engineering Documentation: HABS/HAER Standards
• Secretary of the Interior's Standards for Historic Vessel Preservation

Additional Resources

WBDG

Design Objectives

Historic Preservation, Sustainable

Products and Sytems

Federal Green Construction Guide for Specifiers

Government Agencies

• U.S. General Services Administration
• Sustainable Design Program
• Historic Preservation

Organizations and Associations

• The Association for Preservation Technology International
• National Preservation Institute
• National Trust for Historic Preservation
• Sustainable Buildings Industry Council
• U.S. Green Building Council

Online Articles

• Preservation Brief 3: Conserving Energy in Historic Buildings, National Park Service
• Sustainable Design and Historic Preservation, Sharon C. Park, National Park Service (PDF 336 KB, 4 pgs)

Publications

• Environmental Resource Guide The American Institute of Architects.
• Preservation Brief 44: The Use of Awnings on Historic Buildings by National Park Service. 2004.
• Sustainable Architecture: White Papers Earth Pledge, 2000.
• Thermal Delight in Architecture by Heshong, Lisa. Boston, MA: MIT Press, 1999.

Government Agency Historic Preservation Resources

• Department of the Army
• Agency's Historic Preservation Policy, Procedures, Guidance, Relating to Buildings and Structures (Appendix C)
• U.S. Army Environmental Command
• USACE Tribal Issues
• Department of Navy
• U.S. Navy Historic Preservation
• Department of Veterans Affairs
• Office of Facilities Management—Historic Preservation
• National Park Service
• National Register of Historic Places
• Technical Preservation Services Branch
• U.S. General Services Administration
• Historic Preservation

Other Agencies/Organizations

• The American Institute of Architects (AIA) Historic Resources Committee
• American Institute for Conservation of Historic and Artistic Works (AIC)
• American Society of Landscape Architects (ASLA)
• The Association for Preservation Technology International (APT)
• National Alliance of Preservation Commissions (NAPC)
• National Conference of State Historic Preservation Offices (NCSHPO)
• National Trust for Historic Preservation (NTHP)

Incentives for Historic Buildings

• Tax Incentives for Historic Buildings

How to Find a Preservation Professional

(e.g., preservation consultants, architectural historians, architectural or fine arts conservators, technical consultants, including structural, mechanical, electrical, and civil engineers, etc.)

• The American Institute of Architects
• American Institute for Conservation of Historic and Artistic Works
• The Association for Preservation Technology International
• Federal Agency Lists of Pre-qualified Bidders (GSA, Smithsonian) including federal methods of solicitation and selection
• Federal Preservation Officers
• Local Historical Societies (contact your SHPO for list of local organizations)
• National Trust for Historic Preservation
• State Historic Preservation Offices
• State Nonprofit Preservation Alliances

Technical Information on Historic Materials

• American Institute for Conservation of Historic and Artistic Works
• ASTM International
• The Association for Preservation Technology International
• General Services Administration (GSA)—Specifications for historic buildings
• National Institute of Standards and Technology (NIST)
• National Park Service Preservation Briefs
• Preservation Trades Network
• Conservation Principles, Policies, and Guidance for the Sustainable Management of the Historic Environment(PDF 133 KB)
• Consiglio Nazionale delle Ricerche: Dipartimento Patrimonio Culturale: Studies the effect of the environment on cultural heritage