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The accepted definition of sustainability from the U.N. World Commission on Environment and Development's 1987 report, "Our Common Future" is that sustainability involves "meeting the needs of the present without compromising the ability of future generations to meet their own needs." The intersection of sustainable design and historic preservation would seem a natural alliance.

Older and historic buildings comprise more than half of the existing buildings in the United States. Retention and adaptive reuse of these buildings preserves the materials, embodied energy, and human capital already expended in their construction. The recycling of buildings is one of the most beneficial "green" practices, and stresses the importance and value of historic preservation in the overall promotion of sustainability.

OHP promotes energy and resource conservation in historic buildings and believes this can be accomplished responsibly without compromising the qualities that define their intrinsic historic character. This web page intends to further the discussion and provide examples of sustainability in preservation.

Maydestone Deep Energy Retrofit Report

Maydestone Final Energy Report
The Maydestone Deep Energy Retrofit Report has been released by the Sacramento Municipal Utility District (SMUD). This report studied the energy usage for one year of the Maydestone Apartments Historic Preservation Tax Credit project, which received many energy saving features at the time of the renovation. Download the complete report here.

The report describes the energy conservation features installed, and compares their simulated performance to their actual performance. This technical report informs developers, preservation professionals, engineering consultants and the general public of the feasibility and success of an energy retrofit on a historic rehabilitation.


2016 CA Energy Code Part 6 Draft Language

Concern has been expressed regarding the draft 2015 ICC Energy Code (IECC) that mandates the provisions of the energy code for historic buildings unless a report has been submitted to the Code official demonstrating that compliance with that provision would threaten, degrade or destroy the historic form, fabric, or function of the building. While other parts of Title 24 adopt the ICC Model Code, the Energy Code Part 6 does not. Draft language for the 2016 California Energy Code is available here in PDF format. By downloading the proposed Code language and searching on the key word "historic", all exemptions and requirements for historic buildings can be found. It appears from an initial search that existing language is left intact for the 2016 Part 6 revision.

2013 CALGreen Update Summary
CALGREEN, 24 Part 11, has been updated for 2013. The update clarifies existing code adds new requirements for Water Efficiency, Building Maintenance Operation, Pollution Control and Outdoor Air Quality. Download a summary of changes to the Code here.

Certain sections do not go into effect until July 1, 2014. A bulletin describing those sections may be found here.

2013 Residential Compliance Manual Introduction
Concern has been raised that the new CALGreen Code requires window replacement in existing construction.  Part of the CALGreen update includes the removal of conflicting direction with other parts of the Code, including Part 6 Energy Efficiency. The 2013 Residential Compliance Manual supplements and provides guidance for Part 6 Energy Efficiency. The Introduction to the 2013 Residential Compliance Manual provides a summary of the current code, including guidance on historic residences, which still retains qualified exemptions.  The Introduction to the Manual can be downloaded here.

In addition, Section 3, Building Envelope Requirements of the 2013 Residential Compliance Manual, paragraph 3.5.3.B of 'Mandatory Measures, Feature and Devices', states that:
"Site-built Products. There are no specific air leakage requirements for site-built fenestration products but the Standards require limiting air leakage through weatherstripping and caulking."

It appears that no requirement to replace existing windows exists at this time, and that qualified historic residences are taken into consideration. Design professionals are encouraged to review this information provided in the context of all Code requirements for their specific project.


LEED ND and Historic Preservation
The U.S. Green Building Council has released guidelines for using their LEED for Neighborhood Development product as a tool for preservation.  The guidelines quotes from the recently released report from the National Trust's Preservation Green Lab to make the case that the reuse of historic buildings avoids the energy that would be consumed in the procurement, manufacture, transportation and assembly of virgin materials into a new building.

The Guidelines provide compelling reasons to retain and reuse historic buildings, which are typically already strategically located in well-developed locations with existing infrastructure in place.  The Guidelines further provide instructions to incorporate the rehabilitation of historic buildings into their LEED for Neighborhood Development product, and givers three case studies of projects that have accomplished LEED ND Certification.
Download the PDF file here.


A report just produced by the National Trust for Historic Preservation Green Lab provides cost guidance for homeowners weighing the financial and energy tradeoffs between replacing or repairing older, less efficient windows. This report, "Saving Windows, Saving Money: Evaluating the Energy Performance of Window Retrofit and Replacement", builds on previous research by examining multiple window improvement options, comparing them to replacement windows across multiple climate regions.

PDF of Report: National Trust

Saving Windows, Saving Money’s key findings offer homeowners, contractors, architects and others with compelling evidence of the merits of retrofitting windows as opposed to outright replacement.

Key findings include:

► Retrofit measures can achieve performance results comparable to new replacement windows. This study shows that there are readily available retrofit measures that can achieve energy savings close to new, high performance replacement windows when the performance for each upgrade option is taken into account.

► Almost every retrofit option Offers a better Return on Investment (ROI) than replacement windows. Findings from the cost analysis showed that new, high performance windows are by far the most expensive measure, costing at least double that of common retrofit options when considering materials, installation and general construction commonly required for an existing home. In all climate zones analyzed, cellular shades, interior storm panels and various exterior storm window configurations offer a higher average return on investment compared to new, efficient replacement windows.

►The Bottom Line. Retrofitting windows with high performance enhancements can result in substantial energy savings across a variety of climate zones. Selecting options that retain and retrofit existing windows are the most cost effective way to achieve these energy savings and to lower a home’s carbon footprint. Retrofits extend the life of existing windows, avoid production of new materials, reduce waste and preserve a home’s character.


OHP is pleased to announce the awarding of two “Historic Communities are Green Communities” grants for the 2013 fiscal year.

The San Francisco Planning Department was awarded a $22,453 grant with a proposal to integrate historic preservation into the effort to create EcoDistricts into the neighborhoods South of Market Street (SOMA).  Innovative ways to repurpose historic industrial manufacturing structures into new green energy manufacturing will be incorporated.  The project will focus on ways in which historic resources can contribute to district scale systems, including how retrofitting could help these resources contribute to and draw from an EcoDistrict.

San Francisco EcoDistrict Map
EcoDistricts have become popular around the world as a means to accelerate neighborhood-scale sustainability, sharing energy distribution, water distribution and wastewater treatment and collective solid waste and recyclable processing. They are typically designed and built new. San Francisco is pioneering the retrofit of existing neighborhoods to fit the EcoDistrict model.

A final report will be made available at the conclusion of the Grant funding period showing implementation plans that will augment the EcoDistrict and Central Corridor land use plans. Recommendations for policies and programs that support retention of historic buildings as components of district scale systems, including policy impacts on economic viability, standards for process and review, code amendments, and interagency coordination will additionally be discussed.

North Park Main Street (San Diego) was awarded $22,500 for its proposal to continue the work they started with the award of the first “Historic Communities are Green Communities” grant, which outlined specific methods Owners and Tenants of historic North Park properties could retrofit their building envelopes using the Secretary of the Interiors Standards for Rehabilitation to become more energy efficient, as well as ways to conserve water, energy and materials.  The focus of this grant will create a Virtual Sustainability Center, which:

• brings the goals of preservation and sustainability directly to the public
• provides a connection between preservation and sustainable practices
• provides a database of historic structures in the district, highlighting improvements and sustainable alterations made to them.
• includes specific notes about the preservation of the resources. The SOIS will be directly referenced.
• includes case studies of successful integration of sustainable strategies while keeping the historic nature.

North Park Land Use Map                     Rendering

In addition, the progress of these measures is tracked by calculating and collecting sustainable results, so that:
• carbon and water footprint baselines can be established;
• greenhouse gasses can be inventoried;
• climate data can be registered;
• historical data for use in promoting best sustainable practices can be assessed.

North Park Historic Building 2               Storefront Shading

The results will be documented with a short digital movie, which will highlight green activities of Owners, tenants and community organizers, document case studies with interviews of business and historic building owners, and promote business community participation in the NPMS program.

To download the whole report, see the "Sustainable North Park Main Street Report" link below.

Congratulations Grant award recipients!


In 2009, Wayne Donaldson, California’s State Historic Preservation Officer, challenged North Park Main Street to become the state’s first Sustainable Main Street program. Community leaders embraced this challenge and later that year convened a group of local stakeholders to develop the framework of a sustainability plan in North Park. Working in partnership with OHP, volunteer professionals at Platt/Whitelaw Architects, OBR Architecture, and Zagrodnik+Thomas Architects, NPMS has completed its Sustainable North Park Main Street Study. This Study models energy conservation retrofits using prototypical North Park commercial buildings and expected energy savings, and provides concrete examples of conservation practice for energy, water, open space and tenant operations.

Environmental Quantification of Historic Buildings Report from National Trust

The Greenest Building: Quantifying the Environmental Value of Building Reuse, the eagerly anticipated report from the Preservation Green Lab of the National Trust for Historic Preservation is now available. This report which provides the most comprehensive analysis to date of the potential environmental benefit of building reuse, concludes that, when comparing buildings of equivalent size and function, building reuse almost always offers environmental savings over demolition and new construction.

The report’s key findings offer policy-makers, building owners, developers, architects and engineers compelling evidence of the merits of reusing existing buildings as opposed to tearing them down and building new.

  • Reuse Matters:  Building reuse typically offers greater environmental savings than demolition and new construction. It can take between 10 to 80 years for a new energy efficient building to overcome, through efficient operations, the climate change impacts created by its construction. The study finds that the majority of building types in different climates will take between 20-30 years to compensate for the initial carbon impacts from construction.

  • Scale Matters:  Collectively, building reuse and retrofits substantially reduce climate change impacts. Retrofitting, rather than demolishing and replacing, just 1% of the city of Portland’s office buildings and single family homes over the next ten years would help to meet 15% of their county’s total CO2 reduction targets over the next decade.

  • Design Matters:  The environmental benefits of reuse are maximized by minimizing the input of new construction materials. Renovation projects that require many new materials can reduce or even negate the benefits of reuse.


Repair or replacement of original windows is always one of the hottest topics in preservation. There are reasons to replace windows that are too deteriorated to be technically feasible to repair, but energy conservation is not a reason in and of itself to replace an original window. Our new web page WINDOW REPAIR & RETROFIT: Studies + Research  features several well-documented studies that demonstrate repair as a viable and preferable sustainable choice. These studies are guaranteed suitable for printing out and waving in the air at your next historic preservation meeting.


Cities are beginning to include CEQA requirements to mitigate greenhouse gas production in their General Plans. Some cities with good examples are showcased on the Legislation, Policies, Ordinances  page.

Major Renovation Design Incentives:  Savings By Design is offering incentives to designers of nonresidential new construction or major renovation projects that are located within the service territory of a participating utility and will reduce Title 24 energy consumption requirements by at least 15% on a whole building performance basis. Check here for all the requirements of the program.


There has been concern among historic preservation commissions as to how or whether to approach the review of design of solar installations in historic districts or on historic resources. Parts of the language contained within the Solar Rights Act suggest that no "aesthetic" reviews are permitted. However, the Solar Rights Act, interpreted as a whole, suggests alternative courses of action. Visit our Solar Rights Act web page to learn more.


OHP is seeking examples of California green preservation rehabilitations, both LEED certified and non-LEED certified, sustainable local ordinances that incorporated historic building considerations, and stories of green and preservation experiences. Questions and/or examples can be forwarded to Mark Huck, AIA, LEED AP.