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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 significant of the embedded energy of maintenance and operations for the entire life of the building. Sustainability begins with preservation. The report The Greenest Building: Quantifying the Value of Building Reuse delved into the question of how green an existing building truly is. The Preservation Green Lab, a part of the National Trust for Historic Preservation, with the assistance of building constructors, sustainability consultants and life-cycle analysts, established a set of case studies of recognizable building types; both renovated existing and new construction, in order to quantify the benefits of building reuse against that of new construction.
The Association for Preservation Technology International's Sustainable Preservation Technical Committee (TC-SP) recognizes the imperative for leadership through preservation to address the causes and effects of the climate crisis. Through research, collaboration, outreach, and education, the TC-SP facilitates technical information exchange about the physical, social, and cultural aspects of environmental sustainability and promotes best practices for climate action through the responsible stewardship of our built heritage and cultural landscapes.
Recent advances in life-cycle analysis (LCA) typically used in product design, are expanding into building/construction materials allowing the team to review new construction energy impacts. With some exception, comparing similar uses, types and locations, the existing buildings reduce climate impact over the newly built. Additionally, the studies suggest that even sustainably-constructed new built structures do not recoup energy outlays for approximately 30 years when measured against a renovated existing building. While more development is needed to mature the LCA approach, studies show reusing older buildings result in immediate and lasting environmental benefits.
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.
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 development of the International Green Construction Code (IgCC) by the International Code Council (ICC) is intended to become a new overlay standard to encourage the integration of sustainable design into new construction. The IgCC also provides provisions for existing buildings and existing building sites to incorporate sustainable design practices. This overlay code allows for local jurisdictions to tailor, through adopting electives, suitable options that address local and regional sustainability goals. Green building rating systems continue to grow in importance and prominence and have expanded to include existing buildings over the years. The USGBC's LEED rating system, the Living Future Institute's Living Building Challenge, Green Globes, the International Well Building Institute's WELL Standard, PHIUS (Passive House Institute U.S.), or the Sustainable SITES Initiative may all play a role in a project or be required. So be sure to check for the latest requirements to determine how best to implement them to an existing historic building or historic architectural work.
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's LEED® Building O+M is 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:
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 high albedo porous paving, such as masonry pavers, reduce heat island effects and create the added benefit of controlling storm water runoff. Where treatment of run-off water is required provide an impervious barrier below a pervious surface to direct runoff to an oil-water separator and/or a treatment facility.
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.
Outdoor 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 these traditional water conservation methods. Specify low flow toilets and water conserving fixtures or consider options that are similar to historic water conservation methods.
"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 and respected, even historic plantings that may not be native species. Efficient irrigation systems may be used to save water, and recycled 'gray' 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.
Energy and Atmosphere
Green buildings address energy and atmosphere issues through strategies that reduce the amount of energy required, and by using more benign or renewable forms of energy. Suggestions on approaches to the specific LEED credits within this category are discussed below.
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.
The increasing availability of energy modeling software allows the historic preservation and design team members to collaborate at the early stages of design to tailor high-performing interventions without compromising historic fabric. Digital analysis of existing historic envelope assemblies may reveal opportunities and risks. The result is a more appropriate design of mechanical systems and thermal insulation values. Computational energy modeling may also reveal new paths for meeting requirements associated with building rating systems and energy codes.
Renewable Energy Production
A project should be assessed for the potential to incorporate on-site renewable energy including solar, wind, geothermal, low-impact hydropower, biomass, and biogas strategies in order to reduce environmental and economic impacts associated with fossil fuel energy use.
Green Power and Carbon Offsets
A "no impact" way to capitalize on renewable resources is to buy energy produced remotely. This avoids the need for expensive "add-ons" that have the potential to adversely affect the character of a historic building. Wind power and ground-source energy can be purchased from the local utility company at reasonable rates.
Reuse of Historic Windows
Historic windows are important features that can be upgraded to meet energy efficiency, security, and other requirements. While federal energy saving standards and LEED® rating targets, in particular, encourage use of highly energy efficient windows, historic window replacement is rarely the only option for meeting building performance goals. Original windows are character-defining features, often made of durable old growth wood that is no longer available. With proper maintenance, windows built from old growth wood can function indefinitely and their performance can be substantially bolstered by using caulk, and weather-stripping to eliminate infiltration, or adding using storm windows to reduce heat gain and loss, provide a sound barrier or protect occupants from glass fragmentation risks.
Studies have shown that these simple improvements can result in efficiency similar to that of new insulated glass windows. Many modern replacement windows have a relatively short lifespan, compared to historic windows, and are made of glazing assemblies that cannot easily be repaired, leading to a cycle of disposal and waste that conflicts with sustainability goals for protecting the environment as well as Secretary of the Interior Standards for protecting cultural resources. The most environmentally responsible approach is to maintain, repair, and retrofit historic windows for improved performance, whenever possible, rather than replacing them.
Optimizing any building's energy performance requires evaluating the building enclosure, systems, and occupants together as a whole. For example, 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.
Some historic buildings also featured hinged, wood storm windows that can be reused. Historic windows were constructed of dense, old growth wood. Where this is not the case, a new storm window can be mounted to the existing window—interior or exterior—to provide an extra layer between the occupant and the elements, with little change to the historic character of the building. The Window Preservation Standards Collaborative is one initiative that is being taken to perform testing and develop data on historic window performance and repair standards.
Projects exploring historic window replacement need to examine window conditions throughout the building and consider alternatives that preserve as many historic windows as possible. This might entail replacing only irreparably deteriorated windows, consolidating sound windows on principal facades or lower stories most visible to pedestrians.
To assist federal asset management and design teams in identifying issues to be addressed and objectively comparing appropriate alternatives, the U.S. General Services Administration has prepared a guideline, Upgrading Historic Windows , that includes a window project analysis matrix for assessing a range of factors to be considered in a potential window replacement scenario. These factors include:
- preservation of historic materials,
- preservation of historic design and appearance,
- long-term performance, maintained as directed,
- maintenance requirements/convenience,
- life-cycle cost,
- energy performance, and
- security (blast resistance) requirements, if applicable.
Appropriate analysis of the window upgrading options promotes sound decisions, wise use of federal funds and conservation of finite resources.
Materials and Resources
Building Life-Cycle Impact Reduction
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. Retain, repair, or upgrade historic fixtures, rather than replace them.
Exterior and Interior Materials
While LEED® is now more focused on the value of durable materials in sustainable buildings, the extensive 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 embodied energy of existing materials in approaching rehabilitation of interior spaces.
Indoor Environmental Quality (IEQ)
Use Low-Emitting Materials
Early paints and stains featured pigments made from natural plant materials and minerals. Use low- or no-volatile organic compounds (VOC) finishes.
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, Standards, and Guidelines
- International Code Council ICC IgCC International Green Construction Code
Standards and Guidelines
- ASTM E2813, Standard Practice for Building Enclosure Commissioning
- NPS-28 Cultural Resource Management Guideline
- Secretary of the Interior's Standards for Rehabilitation and Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings
- Secretary of the Interior's Standards for the Treatment of Historic Properties
- Guidelines for the Treatment of Cultural Landscapes
- The Secretary of the Interior's Standards and Guidelines for Archeology and Historic Preservation (As amended and annotated by the National Park Service)
- Heritage Documentation Programs: HABS/HAER/HALS
- Secretary of the Interior's Standards for Historic Vessel Preservation Projects
- UFC 1-200-02, High Performance and Sustainable Building Requirements
Organizations and Associations
- Association for Preservation Technology International
- Green Building Initiative (Green Globes)
- International WELL Building Institute
- International Living Future Institute
- National Preservation Institute
- National Trust for Historic Preservation
- Phius (Passive House Institute U.S.)
- Sustainable SITES Initiative
- U.S. Green Building Council
- Window Preservation Standards Collaborative
- "An Analysis of the Thermal Performance of Repaired and Replacement Windows," by Robert Scope and Bradford S. Carpenter, Vol. XL; No. 2, 2009
- Dallas Hall, Southern Methodist University, small project case study of dome waterproofing
- Development of Fire Mitigation Solutions for PV Systems Installed on Building Roofs—Phase 1, NFPA Fire Protection Research Foundation report, July 2016.
- Energy Efficiency and Renewable Energy Tax Incentives Federal and State Energy Tax Programs by Jerome L. Garciano. July 2013
- Environmental Resource Guide by The American Institute of Architects.
- Heat Island Compendium by the U.S. Environmental Protection Agency
- Preservation Brief 3: Improving Energy Efficiency in Historic Buildings, National Park Service
- Preservation Brief 9: The Repair of Historic Wooden Windows by National Park Service
- Preservation Brief 13: The Repair and Thermal Upgrading of Historic Steel Windows by National Park Service
- Preservation Brief 44: The Use of Awnings on Historic Buildings by National Park Service
- Saving Windows, Saving Money: Evaluating the Energy Performance of Window Retrofit and Replacement, by the National Trust for Historic Preservation Green Lab
- Sustainable Architecture: White Papers Earth Pledge
- Sustainable Design and Historic Preservation by Sharon C. Park, National Park Service
- Testing the Energy Performance of Wood Windows in Cold Climates by Vermont Division for Historic Preservation, funded by NCPTT, 1996-08.
- Thermal Delight in Architecture by Heshong, Lisa. Boston, MA: MIT Press. December 1979.
Government Agency Historic Preservation Resources
- Advisory Council on Historic Preservation (ACHP)
- Department of the Army
- Department of Navy
- Department of Veterans Affairs
- National Park Service
- U.S. General Services Administration
- The American Institute of Architects (AIA) Historic Resources Committee
- American Institute for Conservation (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 Officers (NCSHPO)
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 (AIA) Historic Resources Committee
- American Institute for Conservation
- The Association for Preservation Technology International
- Federal Agency Lists of Pre-qualified Bidders (GSA, Smithsonian) including federal methods of solicitation and selection
- Advisory Council on Historic Preservation-Federal Preservation Officers
- Local Historical Societies (contact your SHPO for list of local organizations)
- National Trust for Historic Preservation
- State Historic Preservation Officers
Technical Information on Historic Materials
- American Institute for Conservation
- ASTM International
- The Association for Preservation Technology International
- Conservation Principles, Policies, and Guidance for the Sustainable Management of the Historic Environment
- Consiglio Nazionale delle Ricerche: Dipartimento Patrimonio Culturale: Studies the effect of the environment on cultural heritage
- General Services Administration (GSA)—Preservation Tools and Resources
- National Institute of Standards and Technology (NIST)
- National Park Service Preservation Briefs
- Preservation Trades Network