The built environment accounts for 40% of global emissions. Facing increasing pressure from investors and regulatory agencies to demonstrate environmental and social responsibility, owners and managers of commercial real estate (CRE) are focused on improving energy efficiency and sustainability in their portfolios. But what about historic properties—can owners of historic properties achieve efficiency and sustainability goals?
Often perceived as inefficient and antiquated, historic buildings may be viewed as an obstacle to, rather than a vehicle for, sustainable improvements. It may seem cost-prohibitive to bring historic buildings up to current standards. Furthermore, regulations meant to protect historic features may make owners or prospective buyers reluctant to even attempt to improve them. Perhaps because of this, many historic buildings are exempt from energy conservation codes that apply to new construction—but that doesn’t necessarily absolve owners of responsibility for the environmental and/or social impacts of their historic buildings or remove the pressure to show environmental stewardship. Fortunately, these perceptions of historic buildings are far from the truth. Historic buildings can contribute to positive ESG (Environmental, Social & Governance) metrics and play a valuable role in improving the efficiency and sustainability of a CRE portfolio.
Inherent Efficiencies of Historic Buildings
Built before modern HVAC and lighting systems were available, historic buildings rely on passive design which takes advantage of daylight, solar orientation, and ventilation to reduce the need for heating and cooling. Features such as operable windows; clerestory windows and skylights offer natural light and fresh air. Wide, overhanging eaves; exterior awnings and shutters; and/or heavy masonry walls provide thermal regulation.
Furthermore, by virtue of their age alone, historic buildings are inherently sustainable. Built with long-lasting, traditional, locally sourced materials that have stood the test of time, they have provided decades, even centuries, of function.
Environmental Benefits of Using Historic Buildings
Each year, approximately 1 billion square feet of buildings are demolished and replaced with new construction in the USA. Adaptive reuse and rehabilitation of existing buildings is akin to recycling—inherently sustainable and better for the environment than demolition and new construction.
According to Carl Elefante, past president of the American Institute of Architects (AIA), “the greenest building is one that is already built.” Compared with new construction, remodeling historic buildings uses less energy and building materials. One study estimated that a new, green, energy-efficient office building that includes as much as 40 percent recycled materials would nevertheless take approximately 65 years to recover the energy lost in demolishing a comparable existing building.
Improving the Efficiency of Historic Buildings
Yes, historic buildings can be adapted for energy efficiency. There are many examples of historic buildings throughout the world that have received substantial green improvements conducted in an impactful yet sensitive way. These improvements provide real benefits to the environment and building occupants while preserving historic character.
Proposed energy efficiency improvements must be assessed for their potential negative impact on a building’s historic character. Special care must be taken not to damage, remove, destroy, or drastically change significant historical features while completing renovation and rehabilitation works. Typically, statutory approval will be required, depending on local regulations.
Many simple upgrades can improve the energy efficiency and/or reduce carbon emissions of historic properties. With careful implementation to protect and enhance the building in question, any of the following measures might be appropriate:
- Ensure building envelope is in good condition to reduce drafts and leaks
- Reglaze existing historic windows with slimline double-glazed units
- Install underfloor heating, warmed by ground source heat pumps
- Install photovoltaic cells on south-facing roofs
- Install MVHR system using historic chimney flues as vent routes
- Use recycled materials such as steelwork and certified timbers
- Add roof insulation
- Add vapor-permeable insulation to inner face of external walls
- Install LED light fittings, low water use fittings, and/or heat pumps
- Switch to green and clean sources of energy
- Install smart thermostats
- Add secondary interior glazing for insulation and soundproofing
- Add shade trees
- Add window shades
More radical options also exist, as appropriate. However, it is first important that upgrades and improvements be designed to complement and work effectively with the building’s inherent original efficiencies.
The cost of adapting historic properties can be significantly offset by financial incentives, particularly Historic Tax Credits (HTCs). HTCs are available for buildings listed on the National Register of Historic Places (NHRP). Even if a property is not currently listed on the NHRP, if it is architecturally and historically significant and over 50 years old, there is an opportunity to apply to have the building listed on the NRHP to create eligibility for HTCs.
Because the regeneration of historic properties and neighborhoods can be the catalyst that a community needs to spark social, economic, and environmental revitalization, federal and state governments offer tax credits to subsidize rehabilitation of designated historic buildings. These can also be paired with other financial motivators such as Solar Tax Credits, Low Income Housing Tax Credits, New Market Tax Credits, PACE funding, TIF, Opportunity Zones and Brownfield incentives to contribute significantly to the capital stack of the project.
Getting Off on the Right Foot
Improving the efficiency and sustainability of a historic building begins with forming an integrated team. The team should include energy and engineering experts as well as a historic architecture consultant with technical expertise in building science to ensure that the character and integrity of the building is maintained during any upgrades. A qualified team will help navigate regulatory and approval requirements, secure financial benefits, deliver real energy efficiency improvements, and protect what is best about the buildings.
Don’t implement energy-retrofit measures without first diagnosing the building’s performance, physical condition, and energy needs. Conduct an energy audit early in the project to determine where problems exist and identify opportunities for improvements. Work with your team to determine which measures will be most cost effective and provide the maximum comfort and energy savings.
Smart and substantial upgrading of historic buildings will help mitigate climate change, benefit the economy, and preserve culture, history, and local identities. With careful handling, these buildings with a prestigious past can contribute to a low-carbon future.