Hollybourne Cottage
Constructed in 1890 for Charles Stewart Maurice—a naval veteran of the US Civil War and a successful engineer and bridge builder—Hollybourne Cottage is one of a number of structures constituting the Jekyll Island Historic District in Georgia, USA. The T-shaped building is a two-and-one-half-story (approximately 280 square meters per floor with a 2.5-meter ceiling) residence set upon a full basement. A steep, narrow stairway connects all floors of the house, while a main stairway connects only the first and second floors. Exterior walls are composed of faux tabby concrete and the foundation system consists of double brick walls that carry much of the structural load.
Following a period of climate monitoring inside and outside the structure, a climate-control system was installed at Hollybourne Cottage in June 2000. The basic system consists of sets of supply and exhaust fans; convection heaters and/or dehumidifiers; sensors measuring relative humidity and temperature; and a programmable controller. Based on comparisons between inside and outside relative humidity, the controller determines whether ventilation or heating/dehumidification is necessary.
During the Hollybourne Cottage field study, the climate-control system passed through several phases in which programming and equipment modifications were implemented. The final phase established two zones that work independently of each other: 1) the basement and 2) the first floor, second floor, and attic.
In zone 1 (the basement), ventilation and dehumidification are used in concert to maintain relative humidity below 75%. In addition to controlling relative humidity, ventilation is also used in zone 2 (first floor, second floor, attic) to remove accumulated heat, particularly in the attic space. Zone 2 heating is restricted to the attic space and is primarily used during winter months, when a reduction in air temperature produces higher levels of relative humidity. From January 2004 to September 2005, RH levels below 70% were maintained approximately 90% and 80% of the time during the study interval for zones 1 and 2, respectively.
In 2004 the climate-control and monitoring system at Hollybourne Cottage was donated to the Jekyll Island Authority, although the Conservation Institute maintains an advisory role.
The summary of experiments conducted at Hollybourne Cottage was presented at the annual meeting of the Association of Preservation Technology International (APT) in Georgia, September 2006, and published in the APT Bulletin.