Window(s) to the Past: A Case Study at Oregon State University

By Hennebery Eddy

At Oregon State University, Hennebery Eddy is leading the design of a $24 million rehabilitation of Strand Agriculture Hall, a 100-year-old building with over 460 original wood windows.  The building is in the heart of the Oregon State University National Historic District, and a  priority of the project is to preserve the historical character of the building, including the character of its windows.

The design team performed a detailed and systematic assessment of the building’s existing wood windows.  It was determined that, with some exceptions, the windows were in very good condition.  The team considered a range of options, including replacing the existing windows with new.  Given the windows’ good condition, however, the team has decided to pursue rehabilitation rather than replacement.

One typical window was chosen in order to test the proposed method of rehabilitation, which included: the removal, stripping, repainting, and reinstallation of sashes; replacement of glazing compound; restringing weights; and replacement of weatherstripping.

Additionally, the window was tested for hazardous materials; there was no asbestos, but it was found to contain high levels of lead in its paint.  The University’s Department of Environmental Health and Safety has strict rules in place regarding the abatement of  hazardous materials, designed to protect students, staff, and faculty.  The guidelines allow the lead paint in the sashes to be abated off-site at the facility performing the window repairs.  The lead paint on the window frames however – which are remaining in place on the building – is required to be abated by a second contractor, hired directly by the University.

The cost of the work done to the test window (including off-site abatement) was approximately $1,750.  Cursory pricing estimates by the project’s general contractor indicated that the cost of a replacement window (with off-the-shelf profiles, built to a custom size) would be approximately 50% greater than the cost of the thorough rehabilitation described below.  If the team wished to pursue custom historically accurate sash and frame profiles, the cost could be twice as much as the rehabilitation option.  It is also unclear whether a manufacturer would be able to fabricate wood windows large enough (6 feet wide by 9 feet tall) to replicate the largest windows in this building.  Early estimates indicated that the overall cost impact of choosing the rehabilitation approach, considering the large number of windows in the building, could translate to a cost savings approaching $1 million.  These estimates did not consider the cost of on-site lead abatement, which is unknown at this point but will likely be significant.

It is anticipated that the rehabilitation measures listed above will result in a physically sound and historically appropriate fenestration solution for this project, achieved within a limited budget.  The energy-efficiency of the building should be dramatically improved by reducing the air leakage around the windows, and (by restoring operability to many of the windows) facilitating a passive ventilation strategy.

The test window has recently been reinstalled in the building and the project team will soon be conducting a blower test on the rehabilitated window to compare its infiltration performance to that of untouched existing windows.  This data will be used to quantify the energy performance of the window assembly, and the project as a whole.  Look for part III of this post in the coming months where we will share the resulting data and design direction following this analysis.