Museums in Historic Buildings: A Case Study at Independence Hall, Philadelphia, Using Digital Controls to Balance Conservation Needs of Collections and Historic Building Fabric ✓ Most Recent

Modern HVAC systems have been associated with damage to historic buildings through uncontrolled condensation of moisture in uninsulated exterior walls. By using direct digital controls (DDC) in modern HVAC systems, operating protocols can be established to overcome these problems. In 1993, the National Park Service began a multi-million dollar construction project to replace aging utility systems in Independence Hall and four adjacent buildings in Philadelphia, Pa. Under the watchful eyes of the Philadelphia Historical Commission (PHC) representing the City of Philadelphia, who owned the buildings, an innovative strategy for control of the indoor climate was developed and implemented with the installation of a new HVAC system with direct digital controls. The smart building system provides a high degree of control in HVAC systems. Each day's relative humidity setpoint is determined using the previous day's low temperature, but buffered by an annual cycle and a maximum daily swing. At the same time, indoor relative humidity follows an annual cycle to achieve 50% RH in summer and in the winter to maintain indoor conditions such that no condensation forms in exterior walls through the operation of the system. The system also minimizes impacts to historic artifacts. For the last three years, data have been collected from both the operating HVAC system and a separate sophisticated monitoring system to determine the efficacy of the original design. The monitoring system collects air temperature and relative humidity, as well as surface temperature on key building walls and surface moisture readings on window glazing. This presentation will discuss the analytical and political difficulties in developing the control strategy, outline the result of the monitoring campaign, and give some preliminary conclusions on operating the system.

Authors: Jonathan P. Brown, Michael D. Eissenberg, P.E., Bill Brookover

Citation: Indoor Air Quality 2001 Moisture, Microbes, and Heath Effects: Indoor Air Quality and Moisture in Buildings Conference Papers

Keywords: November, California, 2001, IAQ