Abstract
Leadership in Energy and Environmental Design (LEED) is the standard for green building design and green building operations certification in the United States and is becoming more prominent in the world. Cities and states are currently adopting LEED into their general building regulations for public buildings, and many energy codes are now using LEED as a reference for design and construction of new buildings. LEED building criteria are being reinvented as buildings evolve and are now entering their third revision, with the advent of LEED V.3. Each of these revisions addresses new problems arising when existing conditions have been overlooked or new technologies and practices have evolved during the last revision period. New developments in LEED V.3 point models continue to favor new or recent construction as compared with historical buildings. LEED V.3 does not adequately address the major renovation needs required for historical buildings attempting to maintain their historical fabric.
This article addresses the current problems for historical buildings attempting to achieve LEED V.3 certification, specifically focusing on two LEED rating systems, LEED for New Construction and Major Renovations and LEED for Existing Buildings: Operations and Maintenance. The intent is to see how current trends in green design and construction are influencing current changes in legislation and the impact of those changes on historical building renovations. Offering new insight into how the United States Green Building Council (USGBC) may approach possible changes to LEED V.3, this article attempts to find new solutions to adequately integrate historical buildings under the LEED umbrella.
Introduction
The environmental costs of construction are greater than any other industry, and energy usage of constructed buildings accounts for 40% of the energy usage worldwide (Cheng, Chiang & Tang, 2005). To combat negative environmental effects during construction processes and building occupancy, the U.S. Green Building Council (USGBC) came up with a green building rating system to encourage intelligent, environmentally conscious building. The system currently developed is Leadership in Energy and Environmental Design (LEED), which concentrates on improving fundamental areas of building design, specifically, “energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts” (USGBC, 2010).
In the certification process, potential LEED buildings amass points in the different design categories to gain a certified, silver, gold, or platinum rating. LEED design fundamentals are currently organized into six areas of certification; neighborhood development, homes, commercial interiors, core and shell, buildings operations and maintenance, and new construction (with individual focus on schools, healthcare, and retail). In 2009, the USGBC updated the LEED system, reweighting many of the categories to account for importance within the categories rather than placing them on a level playing field. Part of this initiative was a response to issues brought up by conservationists who felt existing buildings were not being recognized adequately for existing material content. This paper will focus on two different certifications, LEED for Existing Buildings: Operations & Maintenance (LEED-EB) and LEED for New Construction (LEED-NC). The discussion will look at how existing buildings, specifically historical structures work within the context of LEED V.3 2009 rating system.
LEED touches every aspect of the life cycle of a building—from design and construction, to finance and selling, and through to ownership. The varying range of industries affected during a building’s life cycle can be represented by the increasing number of different green building types whose owners choose to implement green aspects into the construction and maintenance processes (Kelly, 69).
LEED buildings encompass a large variety of building typologies, including educational buildings, government intuitions, medical buildings, housing complexes, homes, churches, theaters, retail buildings, and mixed use with the potential to move into all areas of development. LEED accomplishes this diversity through the use of six areas of certification touching on every perspective of ownership including the complete building owners, leasing building owners, retailers, public owned buildings, renters, etc. With such a broad range of involvement in construction, it is important to understand LEED processes and their impacts upon all areas of design and construction.
LEED New Construction and Major Renovations
LEED for New Construction and Major Renovations (LEED-NC) is designed with conservation in mind, but for the purpose of purely new construction and not for historical conservation practices. Changes to LEED have brought new insight into the practice of conservation by channeling preservation ideals through the certification process. How much can be done using the new LEED V.3 rating system in conjunction with historic conservation is yet to be seen. The benefit of choosing new construction over historic conservation is that new construction can be more readily designed around the current point system as it employs a clean slate system. Historical buildings are fixed construction requiring greater modification for new systems to be integrated into the existing systems. Although there is a cost savings benefit to retrofitting a existing building, the loss of the historical aspects of the building can be more damaging than the environmental benefits. This first section looks at LEED-NC from the perspective of a historical building adapting to the challenges the LEED system. Both historical buildings and newly designed buildings are required to fulfill the same minimum requirement and must operate under the same point system.
Sustainable Sites (SS) outlines possible ways to approach and maintain a site. Water Efficiency (WE) outlines possible water reduction, treatment, and reuse of potable water and non-potable water. Energy and Atmosphere (EA) outlines possible methods for energy savings and increased air quality. Materials and Resources (MR) outlines possible modes for the reuse and recycling of construction materials and operations materials. Indoor Environmental Quality (IEQ) seeks strategies to promote better indoor air quality. Innovation in Design (ID) is an optional credit, requiring design to go above and beyond baseline energy standards outside the stated LEED rating systems (i.e., new green innovation). Regional Priority (RP) is an optional credit achievable by going beyond specific requirements in LEED based on project location.
LEED Existing Buildings: Operations and Maintenance
LEED for Existing Building: Operations and Maintenance (LEED-EB) is designed for completed buildings who wish to continue or begin a relationship with the green lifestyle under the LEED certification process. The concept is revolutionary for existing buildings with no LEED background; certification is now possible under a different set of categories without the expense of renovation. Although the model works for the general umbrella of existing buildings, there are some categorical inconsistencies in the requirements for historical buildings as a product of their age. Below is a look at the different LEED categories. Both historical buildings and newly designed buildings are required to fulfill the same minimum requirements and must operate under the same point system.
Sustainable Sites (SS) outlines methods to deal with the built site in respect to managing and protecting the exterior environment. Water Efficiency (WE) outlines possible water reduction, treatment, and reuse of potable water and non-potable water through retrofitting process of existing fixtures. Energy and Atmosphere (AE) outlines possible methods for energy savings and increased air quality through post construction energy saving measures. Materials and Resources (MR) require use of sustainable purchasing and solid waste management programs that promote high levels of direct material reuse and recycling. Indoor Environmental Quality (IEQ) seeks strategies to promote better indoor air quality by maintaining, retrofitting, or replacing existing air handling units. Innovation in Operations (IO) is an optional credit requiring operations practices and performance to go above and beyond baseline energy standards outside the stated LEED rating systems. Regional Priority (RP) is an optional credit achievable by going beyond specific requirements in LEED based on project location.
Issues with the LEED and Historical Buildings
The current rating systems initiated by the LEED point systems with respect to historical structures does not properly take into account the specific challenges that are required to renovate and maintain an historical property. Under LEED for new construction historical buildings will need to undergo exterior and interior changes to stand up to high levels of certification. The Existing Buildings: Operations and Maintenance rating system would be the natural choice for an historical building project that cannot stand up to the rigors of the LEED-NC rating system, however the requirements are inconsistent between new and existing construction and arguably may not go far enough at times. Developments in historical buildings will result in an architecture of holes, shells, and large adaptable spaces, (i.e., existing gyms or warehouses) in order to conform to the requirements of LEED at the same level of new construction.
LEED for New Construction and Major Renovations
Unbalance can be seen in comparing the sliding scale points under the major category of Energy and Atmosphere as compared to Materials and Resources. Two of the major categories in EA allow up to 26 points combined for energy efficiency and on-site renewable energy (wind, solar, geothermal, etc.), EA Credit 1 and EA Credit 2. Comparably, MR only allows for up to 4 points in building reuse in two combined categories, MR Credit 1.1 and MR Credit 1.2. Energy and Atmosphere is one of the most difficult credits for historical buildings to obtain and Materials and Resources is the easiest. The balance between the two categories is strikingly uneven.
Sustainable Sites category is balanced, as many requirements for building site selection fall under even terms in categories regarding site density and transportation accessibility. There are discrepancies in regard to credits for Credit 6.1 – SS Credit 7.2, storm water design and heat island effect, which would require greater aesthetic changes to an historical building’s roof and exterior landscaping. During the design phase of a newly constructed building, these requirements could be easily and seamlessly designed into the building and site before construction would begin. Historical buildings would be required to adapt physically, removing pieces of their architectural elements to make room for modern technologies.
Meeting Indoor Environmental Quality categories creates greater challenges as existing buildings must follow strict guidelines from ASHRAE 90.1-2007 for dealing with exterior airflow from an air handling unit system or through natural ventilation. While these guidelines are becoming law for many municipalities, meeting or going beyond these requirements for historical renovation projects may cause great aesthetic interior changes to the building envelope as new air handling units, delivery systems, and monitoring systems will be needed to increase required airflow.
LEED Existing Buildings: Operations and Maintenance
Inequalities arise in the Water Efficiency core requirement, as existing buildings older than 1997 are allowed to use 60% more water as compared with new construction. The core requirement is the basis for other requirements in the WE category that utilize the core water usage base requirement for further calculation of water reduction. Arguments can be made whether this gives historical buildings an advantage in the WE category or creates equality with new buildings.
Under the Energy and Atmosphere category, all buildings are required to reach a minimum efficiency in the 69 percentile range against buildings of a like kind (EA Credit 1 1-18 points), however historical buildings are at a disadvantage in this requirement. Also EA Credit 1 is weighted using the core requirement and contains the largest amount of possible point gains (1-18) based on percent efficiency above the 69 percentile. New buildings have greater ability to build efficiency into their design before construction, whereas historical buildings require extensive modifications to existing electrical system requiring removal, relocation, and replacement of many electrical features. In relation to energy usage, air handling and delivery systems will require updates to have units that run with a greater efficiency. Building envelopes will have to be resealed and insulated to maintain a controlled environment for the new system to be efficient.
The Materials and Resources category applies equally to the purchasing and disposal of materials for both historical and newly constructed buildings, but it does not recognize historical buildings as reused materials in the MR credit process. This would appear as a balanced category; however, compared with the SS Credit 1, which awards points to newly constructed buildings that fall under LEED for New Construction, historical buildings are not adequately recognized as stored energy and are awarded nothing for their reuse characteristics.
Meeting Indoor Environmental Quality categories creates greater challenges as existing buildings must follow strict guidelines from ASHRAE 90.1-2007 for dealing with exterior airflow from an air handling unit system or through natural ventilation. Similar to LEED-NC the IEQ category for LEED-EB does not contain extra points for optimized energy performance; however, the base requirement may still require great aesthetic interior changes within the building envelope as new air handling units, delivery systems, and monitoring systems will be needed to increase required airflow.
LEED’s Fundamental Assumptions about Historical Buildings
While LEED integrates ideas of conservation of existing buildings, it does not approach existing buildings as historical architectural artifacts. The USGBC does not weigh new construction against historical structures in the LEED certification process. It has actively been working since 2006 with the National Trust for Historic Preservation and The American Institute of Architects to include provisions that account for historical buildings preservation (Roberts, 2007). To assume the USGBC operates completely without the interest of historic preservation is to ignore the adaptive nature of the USGBC and the LEED rating system to current environmental, social, and technological changes. The LEED rating system, although progressive in change, does not adequately account for the inequities between new construction and historically preserved buildings attempting LEED certification.
Fundamental problems are revealed with “linkages” or connections found between points in the system. Internal linkages, points gained within a credit category that are linked, and external linkages, points that are linked indirectly within two different categories, can create quick point gains in the LEED certification process (Lavy & Fernandez-Solis, 2009). Problems for designers arise when attempting to historically renovate a building under the LEED rating system as many of the large value interconnected points are related to energy usage and air handling efficiency, points difficult for historical buildings to obtain. Moreover, designers often address these interconnected internal and external points first as a way to maximize points in the rating system (Lavy & Fernandez-Solis, 2009).
It may be argued that achieving LEED certification is a difficult task under its current limitations with respect to historical preservation. Existing taboos about green buildings permeate a misunderstanding of the true cost of green buildings, much of which can be contributed to the lack of consistent data on the true expense of green building (Miller, Spivey, & Florance, 2008). Inconclusive data about the effectiveness of green building design predictions and actual outcomes create uncertainty within the construction industry of how to properly design for a LEED building and whether it is even worth pursuing (Beck, 2009). New difficulties faced in achieving LEED certification for historical structures, tied with pre-existing perceptions of high expense and complexity, create a negative environment resisting the desire for LEED certification (Lavy & Fernandez-Solis, 2009.)
Legislation, LEED, and Historical Structures
The face of building and construction regulation is changing, as social responsibility concerns increase among society and energy costs continue to rise. Even as the cost of becoming LEED certified costs a project anywhere from 3% to 8% more, depending on the level of certification (silver to platinum) and location, the push by government institutions to encourage green building on all levels continues to increase (Miller, Spivey, & Florance, 2008).
Governments at all levels are conforming to green standards through LEED in two distinct ways; by creating building laws that require adherence to LEED standards and through green building incentives. Recent Federal incentives, including the Energy Policy Act of 2005 and the American Recovery and Reinvestment Act, allow for tax breaks for green building construction and incentives for investments in green building technologies (Kelly, Bramhandkar, & Rosenthal, 2010). Federal regulations on buildings are often less intrusive in establishing starting points for building laws and regulations. Some local government regulations go further, enforcing strict green building requirements on new and existing construction projects.
Many federal departments have adopted some form of LEED certification for their new building projects (Abair, 2008) and with the passing of the 2009 Stimulus Bill, US$4.5 billion were made available to revamp 75% of federal buildings to make them more energy efficient, further supporting green building and green maintenance in the public sector (Erpenbeck & Schiman, 2009). While the federal government financially backs the green building movement, local governments are effective at instituting green building practices because of their insight into specific localized economic and environmental issues that cannot be handled effectively on a federal level (Retzlaff, 2009).
Municipalities initiate green building regulations in two ways: by mandating requirements for publicly funded building projects and privately funded building projects. Local building codes continue to become stricter, enforcing green building regulations, first for public buildings (government buildings and schools) and now on private projects including new existing buildings. Although three quarters of all “cities and counties” have mandated LEED building systems on all public buildings, “only twelve jurisdictions had enacted a requirement for certain private buildings to use the LEED assessment system.” (Retzlaff, 2009, p.70)
Aimed at reducing carbon emissions, the city of San Francisco has gone even further in green regulatory action by enacting LEED requirements on major renovations to existing private buildings due to the city’s lack of new construction (Hupp, 2009). Although San Francisco’s actions to create an energy efficient city may be viewed as progressive, changes in private building codes across the country will eventually evolve to mirror many of their current building code standards. The level to which each individual community decides to act is different, but with as many as 45 states and 137 cities already issuing some form of LEED initiative, the impact of the green building revolution will continue to be felt in how we live our lives and design buildings (Argibay, 2010).
Cities adopting codes such as San Francisco’s building code for existing buildings that require private building endeavors to be LEED accredited, could cause the purity of strict historical preservation to become threatened. As building codes continue to adapt and be influenced by the green building movement, historical buildings and movements to protect these properties will either come into greater conflict with the LEED system of green building or the two will become a homogeneous composite of new and old ideals.
When LEED is applied to building codes for private development, the reaction may become damaging in one of two ways: by removing the original architectural intent of the building or by removing the building completely. As regulations progress, so will stricter LEED standards for all new and existing buildings. Currently, most municipalities requiring LEED certification do so at a silver level; however, these standards will only continue to become tougher, eventually requiring a gold or platinum rating for many cities (Retzlaff, 2009). Tougher standards will require greater changes to achieve the mandated points forcing designers to change the architectural character of existing buildings under renovation. If owners view renovating existing buildings to LEED building standards as too expensive, and architects find the design process to be too cumbersome, then priority might be given to razing an existing structure in favor of constructing a completely new designed building.
Views of Conservation and the Importance of Historical Buildings to the Green Movement
Appropriate levels of historical conservation of buildings depend on subjective views and the individual buildings to be preserved. Historically, these views have been known as preservation, rehabilitation, and restoration. As progressive ideas of conservation emerge, new concepts can be broken down into three polarizing view points: pure conservation, adaptive conservation, and modern conservation.
Pure conservation ideals react against the idea of changing any element of the building as it is viewed as a purely historical element. In this thought process, the conservationist must work to keep the original historical intent of the building, even to the point of how it operates. As this form of conservation is similar to that of museum pieces, changes to electrical, mechanical, as well as building envelope changes will not be tolerated. Both LEED-NC and LEED-EB would tear at the fabric of the historical and architectural integrity of the building that falls into this group.
Adaptive conservation attempts to change as little as possible by means of replacing damaged or worn out elements with the best period related items through careful recreation. Mechanical and electrical changes would be tolerated as long as the resulting equipment would not be evident throughout the structure (i.e., no visible duct work) and it retains its original architectural purpose. Adaptive conservation has the ability to work with LEED-NC and LEED-EB on basic certification levels; however, as stricter LEED ratings are required, adaptive conservation ideals may conflict with the LEED rating system.
Modern conservation maintains major building elements, but allowing for major additions to update the space to modern use. Most of the building’s major structural elements, exterior envelope, and bearing walls are maintained under modern conservation; however, all forms of building technologies and modern architectural elements are applied to create a new space while maintaining the basic architectural ideas the old building once possessed. Modern conservation is very adaptive and has the greatest capabilities to attain LEED ratings for both LEED-NC and LEED-EB at the highest levels.
Historical buildings not only have value as representatives of a historical moment in time, but as story tellers of energy and effort that took place to create that building. This makes all historical buildings the embodiment of green building. Every material put into a building has a history of energy; from the mining of the raw material, to the manufacturing of that material into a usable product, ending with the process of shipping and installing the product. The total energy of all these materials that make up a building’s components is known as “embodied energy.”
The choice to reuse an already existing structure is the most efficient form of construction when compared with building new. Even when a new building uses strict guidelines to manage waste, recycled content, and local materials, the existing building still performs better creating less waste and lower carbon emissions during construction. While the LEED rating system does account for some of this embodied energy in its current rating system, many historians question whether it goes far enough. In reaction, the USGBC is developing a new rating system called the “Life Cycle Assessment of Building Assemblies” in conjunction with the Materials and Resources section already in place (Campagna, 2008). The new pilot credit is worth a maximum of 7 LEED points and creates a new avenue for historical buildings; however, it only accomplishes this in one category. Comparable with the existing energy efficiency categories, will the points amount to enough to offset the differences seen in historic buildings versus new construction in the LEED rating system?
New Rating System
Current point systems in the LEED rating systems do not account for the challenges faced by historical buildings. While the USGBC is working with National Trust for Historic Preservation to make the LEED system receptive toward historic building challenges, the current process of revision is slow and unorthodox. Each historical building is unique in its design and any conservation effort to restore such a building will require a unique set of ideas and design specifications when integrating LEED standards. A new LEED rating system for historical buildings is needed to address the unique challenges required of historical buildings. With the spirit of the existing rating system, the new system should incorporate the idea of embodied energy into all categories of the system and seek new, unique solutions to historical preservation problems faced in a “green” society. Limitations on how an historical building is defined are needed to instill integrity in the process, as not all old buildings are necessarily historical buildings. A new type of system should be able to weigh historical elements against energy efficiency. If a building uses a system that increases energy efficiency while maintaining the building’s historical integrity, then higher points should be awarded; however, if moderate efficiency is achieved with moderate preservation methods then lower points are awarded. It is important to identify that it should not be either historical preservation or environmental preservation, but a combination of both ideals.
Conclusion
The proliferation of construction pollution and energy usage will persist as populations continue to grow globally. As a reaction, investment in green building and certification on all levels, public and private, promoting responsible building practices will increase, as society increasingly sees positive benefits to such a movement. Existing buildings will play an increased role in this movement, but how is not a complete certainty. There are many differing views on how to approach the conservation of existing and historical structures. The next step is to evaluate appropriately the level to which we give historical buildings credit for simply existing as embodied energy in a “green” society. It will remain important to challenge owners, designers, and constructors not to choose between, but to establish a balance between the architectural history of buildings and the desire to create energy-efficient buildings.
