Over the last few years, The Trustees of Reservations have faced that situation with the William Cullen Bryant Homestead in Cummington, which was built and expanded from the 1780s to1860s. And experiments have yielded some interesting results.
Surrounded by double plaster walls, the Bryant family was ahead of the times in protecting themselves from the winter elements. But as with all old houses, the times have changed. Now, little activity occurs at the Homestead in the offseason, leading The Trustees to try varied approaches for controlling its interior climate—from letting the temperature drop below freezing to supplying minimal heat.
“Very few historic house museums are heated and low temperatures aren’t a problem,” explains regional superintendant Jim Caffrey. “But at this location, abrupt changes in temperatures combined with high humidity are a serious issue. In March and April, condensation inside the basement almost looked like rain.” These conditions were particularly problematic for the period fabrics and the vast collection of books in Bryant’s library. On the other hand, warming the building to 48 degrees through the winter requires some 2,000 gallons of heating oil.
An energy audit revealed tremendous heat-loss through windows and other parts of the house, leading to a multi-faceted response. The Trustees installed a 6-zone system with circulating hot water radiators to generate heat, and then considered the tricky task of insulating a historically significant building. Recycled cellulose insulation was added to the attic, and places of upward air movement were methodically identified and closed off. The historic windows were kept intact, but new locks were added along with silicone gaskets on the sills and brass gaskets on the frame to tighten seals. Transparent plastic coatings were also adhered to the panes, primarily to prevent UV radiation from affecting the artifacts inside, and temporary, reflective coverings were hung to trap heat in winter. There are now a number of manufacturers who also sell “low e” window film that retain heat as well as block UV rays.
Focus then turned to the humidity—which meant the basement. The Homestead’s dirt basement floors and loose stone foundation were the biggest sources of moisture. Staff laid a thick plastic over the floors and hung the same Reflectix covering on the walls as on the windows upstairs. “It kind of looks like a metallic bubble wrap,” said Jim Caffrey, “and serves as a vapor barrier while keeping the heat in.”
After a few more winters, The Trustees will know if further adjustments need to be made. But the initial efforts have already proved that, with a little Yankee ingenuity, the historic buildings that we value can efficiently hold their place in the modern Highlands.