Old is the new New
Historic buildings often incorporate many sustainable features. In addition to skills and design that went into the historic buildings, they are a reservoir of embodied energy. Embodied energy is the energy used to create a product. Building materials require energy for their extraction, manufacture, transportation and construction; in addition, building demolition requires energy for disassembly, removal and transport, and if materials are not recycled these materials add to waste stream.
Historic buildings are therefore an important sustainable resource, and their preservation is a key component of green architecture. In particular many institutions are incorporating green features in new buildings, but sustainability also requires investment in historic structures. Preserving buildings is in some ways akin to recycling.
However, to remain viable historic buildings may require adaptation to make them more energy efficient. Historic buildings are not necessarily energy inefficient, and may actually be more energy efficient than some more recent structures. Even if they are efficient they can often be adapted to increase efficiency. Retrofits may include the addition of thermal insulation of the exterior envelope at walls and roofing. Windows may be modified by the repair of existing, or adding storm units, or existing windows may be replaced with insulating units. Appliances may be replaced with low-energy appliances, and plumbing fixtures with low water consumption fixtures. Solar panels may also be added. Recent developments include building integrated photovoltaic systems that integrate the system with the roofing as opposed to a separate panel system.
With existing buildings, tradeoff of retention of historic materials needs to be weighed against energy saving measures. For example, historic windows in some cases may effectively be repaired in place to limit air infiltration. In other situations the addition of storm units, or replacement with new insulated glass units may be desired. With replacement units the lifespan of the new units needs to be evaluated. Replacing existing windows with new units means the embodied energy of the existing windows will be wasted, so new units should be units with a high life expectancy.
With increasing emphasis on green architecture it will be important to evaluate the effects of sustainable alterations to existing structures. In February, I plan to attend the Association for Preservation Technology symposium entitled “Energy Efficiency, Insulation, and Historic Building Envelopes,” and look forward to finding out more about these opportunities to continue to make our historic buildings viable. Topics of the seminar include insulating historic solid masonry walls, condensation and steel sash windows, and balancing energy performance and durability in historic retrofits. I’ll be reporting back on what I learn so stay tuned.