In April 2016, NSERC CREATE Heritage Engineering organized a workshop on “Sustainable Preservation” with special guest speaker Nancy Rankin of J.G. Waite Associates, New York. Using case studies from Nancy’s practice in the rehabilitation of historic buildings, the workshop considered the impact of design, rehabilitation and retrofit options on heritage structures. Nancy presented case studies on:

  • The Rotunda, University of Virginia, UNESCO World Heritage Site (designed by Thomas Jefferson, built 1822-6);
  • The Pullman National Monument industrial community, Chicago (designed by Solon Spencer Beman, built 1880),
  • Cincinnati Union Terminal, Cincinnati (designed by Paul Philippe Cret, Alfred T. Fellheimer, Steward Wagner and Roland Wank, built 1933);
  • Hamilton Grange National Memorial, New York (designed by John McComb Jr. for Alexander Hamilton, built 1802);
  • Yin Yu Tang, Salem, Massachusetts (built late 18th century in Anhui province, China and moved to Salem 2003);
  • Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary, Baltimore, Maryland (built 1806-21).

Workshop participants divided into four groups to consider each case study in the context of themes in sustainability, based on Jean Carroon’s What Makes Existing Buildings Green:

  • Embodied energy in historic buildings – the attempt to quantify the energy used directly and indirectly in raw material acquisition, production of materials, and assembly of those materials into a building
  • Durability and indigenous materials – the appropriate use of indigenous materials is often demonstrated in historic buildings, including inherent durability for the local climate, lower transportation requirements and support of local economies.
  • Reparability – moving from a culture of replacement to one of repair and renewal is essential for reducing our environmental impact and becoming a regenerative society.
  • Passive survivability – the design features in a building that allow it to function even when modern systems and energy sources fail, are often demonstrated by historic buildings.

An NSERC CREATE professor or collaborator chaired each group and a student acted as rapporteur.

The Durability and Indigenous Materials group considered the ways in which each case study approached the theme and identified three distinct gaps for further research: analyzing compatibility of materials and understanding where appropriate replacement materials can be applied (i.e. composite woods); formulating methodologies to analyze modern heritage; and creating more durable temporary projects to allow for continued use of a building while a long-term strategy is identified. Some of the areas for improvement are: creating better communication between materials research and trades to ensure that everyone has the most up-to-date knowledge about specific materials; establishing historic protection for buildings that are imported from other countries; and putting an emphasis on conserving intangible cultural heritage values.

The Reparability group identified seven issues as important: retain as much as you can; consider the appropriate use of spaces in design planning; implement repairs based on priority of zones; repairing inappropriate interventions; understanding heritage values and character-defining elements before interventions; providing suitable craftsmanship; the adviseability of implementing sacrificial interventions to decrease the deterioration rate; and applying durable interventions. Some of the risks associated with repairs were: interventions often imply new materials and techniques; and implementing modern climate control systems in traditional buildings.

The Passive Survivability group summarized their theme as aiming to maximize the inherent qualities of buildings that allow them to function and to limit the use of active systems to condition spaces. They identified elements of passive survivability in the case studies presented by Nancy Rankin: maximizing natural light through the use of skylights, building orientation and restoration of clear glazing; creating natural ventilation through high ceilings, natural airflow, building elevation and prevailing winds; and using porches, overhangs, shutters and trees to create shading and control solar gains. The group identified three gaps in existing knowledge: the limits of modeling and software, including challenges in capturing certain shapes and details typical of heritage buildings and challenges in transitioning between point cloud data and BIM; the lack of a model for quantification of passive ventilation systems; and the gap between conservation theories and conservation practice.