Sidebar: Historic Preservation and Green Building: A Lasting Relationship
Energy and Atmosphere
Energy Modeling
Model existing buildings using software programs such as Energy-10 or, for larger buildings, DOE-2. Modeling can provide valuable information about how well or poorly an existing assembly is performing and can help the project team overcome biases.
Heating and Cooling
If the building envelope is relatively inefficient, increasing the efficiency of the HVAC system will tend to have a favorable cost-benefit ratio. Efficient systems requiring higher-than-average capital investment, such as ground-source heat pumps, could be more cost-effective in these cases.
Low-Impact Retrofits
Consider using systems, such as radiant heating and cooling and displacement ventilation, that reduce the size of the HVAC system and eliminate the need for ductwork or dropped ceilings that can conceal, destroy, or detract from historic features.
Daylighting
Often built when artificial lighting was less prevalent, many older buildings feature large windows that promote daylighting. Capitalize and expand on those assets when possible, while mitigating against glare, solar gain, and heat loss. In some cases, older daylighting systems were covered up or altered during renovations; restoring original features can sometimes bring daylighting back.
Natural Ventilation
Many historic buildings use (or at one time used) operable windows and other natural ventilation features. Often, these features were altered or sealed during renovations, and restoring these capabilities may reduce energy consumption and improve comfort.
Renewable Energy
Install photovoltaic panels on flat roofs or away from the building where they will not detract from its historic character.
Embodied Energy
In determining whether to rehabilitate or replace a building or building component, factor in its embodied energy compared with that of the replacement building or component. Life-cycle assessment tools such as Athena Environmental Impact Estimator may be helpful.
Refrigerants
Replace CFC-based equipment, or retrofit existing equipment to HFC refrigerant.
Building Envelope
Windows
Restoring historic windows and adding either interior or exterior storm windows can improve energy performance while maintaining historic features. Don’t focus on windows while ignoring the whole building envelope, however; window performance can be a relatively small driver of energy performance, depending on glazing percentage and other factors.
Insulation
Add insulation where possible without damaging historic aspects of the building. Consult a building-science expert to investigate the vapor profile and drying potential of the existing envelope assembly and the proposed rehabilitation to prevent moisture and durability problems.
Roofs
Green roofs and reflective roofs provide various environmental benefits. Neither may be possible for historic sloped roofs, but they should be considered with less-visible low-slope or flat roofs.
Interior
Plumbing Fixtures
Consider replacing underperforming plumbing fixtures with modern, efficient fixtures, or upgrade existing fixtures with components that reduce water use.
Lighting Fixtures
Incorporate appropriate, modern, efficient lighting technology, including lamps, luminaires, and daylighting with occupancy sensors.
Materials
Materials Reuse and Recycling
In addition to reusing structural elements, save building materials from areas that need to be gutted or demolished, and reuse them in a way that is consistent with their historic character. Sell or donate to salvage markets any historic materials that can’t be reused in the building.
Materials
Look for ways to maintain the good indoor environmental quality common in older buildings by specifying nontoxic, low-VOC (volatile organic compound) materials in all areas.
Finishes
Oil-based finishes, which tend to have high VOC content, are often preferred on historic properties for aesthetics and authenticity, even though low-VOC acrylic finishes are often just as good. Whenever possible, choose low-VOC paints and finishes.
Paint Strippers
Though often used in rehabilitation projects, conventional paint strippers, including those containing methylene chloride, are notoriously hazardous and should be avoided. Less-hazardous alternatives are available—look for low-VOC, nontoxic, biodegradable products such as those listed in GreenSpec®Directory.
Hazardous Materials
Remediate or encapsulate hazardous materials, such as asbestos and lead paint, according to relevant local statutes. (These materials typically fall outside LEED requirements for landfill waste diversion.)
Site and Other General Considerations
Monitoring
Conduct as much environmental monitoring as possible prior to doing any work to aid in understanding how the building functions and what environmental impacts are affecting it. Continue monitoring after work is complete.
Expansion
If a building is not large enough for the desired programming, consider expanding it rather than demolishing and rebuilding. Increasing the density of existing buildings creates environmental benefits, and numerous buildings have successfully been expanded—up-, out-, or downward—while maintaining their historic character.
Durability
Many historic buildings have survived because they are aesthetically pleasing, functional, and well built, using durable materials, and because they employ relatively simple, effective, and enduring designs. Identify those factors, and honor, preserve, and learn from them. (See EBN Vol. 14, No. 11.)
Repairability
Older buildings tend to have materials and components that are designed and suited for repair by local tradespeople. Many of those components are relatively efficient, environmentally friendly, and locally available, and the expertise to repair them may still exist. Supporting these local sources supports regional economies and contributes to long-term building maintainability.
Reversibility
When altering features and floorplans of historic buildings, preservationists champion the use of building methods that don’t needlessly damage original features. Design to allow choices to be revisited and changes to be made in future renovations. (See EBN Vol. 12, No. 2for more on designing for flexibility.)
Passive Survivability
Many historic buildings were designed with sensitivity to their sites and built to be relatively capable of withstanding loss of electricity while maintaining livability (see EBN, Vol. 15, No. 5for more on passive survivability). While maintaining some of these features of passive survivability, such as natural ventilation, may be difficult to reconcile with modern energy and comfort standards, inventory these features and maintain or enhance them when possible.
Integrated Design
Use an integrated design process to capitalize on existing green and historic features, and maintain or increase those in rehabilitation. Understand the Secretary’s Standards, and, in turn, discuss and consult with historic preservation experts and NPS authorities on environmental design goals.
Landscaping
The existing site and landscaping plan, if intact, usually contributes to the historic fabric of a building, and the flexibility needed to reduce its maintenance and irrigation needs may be limited. On the other hand, historical research may reveal that original plantings offering environmental benefits were removed over time. Consider adding rainwater catchment and graywater systems to meet irrigation needs.
