Duff House

Context

This building houses a nationally important collection of paintings, furniture and
sculpture. A high quality and well considered restoration and conservation programme took place in the mid 1990’s. The sensitivity of the collection inside the building led to the installation of a centrally controlled heating system supplemented by humidifiers in the gallery rooms.

Issue

There was concern that control over the heating system was not as good as it could be. There was some evidence of condensation on windows, suspicion of rot by Hutton and Rostrun rot-sniffing bloodhounds as well as possible problems with some of the more vulnerable items in the collection.

Investigation

A comprehensive wireless monitoring system (supplied by Gemini Data Loggers) was installed with a temperature and relative humidity sensor-transmitter in most display rooms. This was supplemented by stand alone loggers in the roofspaces as these were out of range of the wireless system.

The heating system was also looked at with a mechanical and electrical engineer. It was discovered that the room thermostats were not installed correctly. The setpoints on the humidifiers were also looked at and their use discussed with staff.

The interplay between heaters and humidifiers was investigated and found that the heaters would easily overwhelm the humidifiers. Adjustments to the setpoints of both were trialed.

Action Taken

New thermostats were installed on most of the heaters to allow a setpoint to be achieved. The Building Management System was upgraded at the same time. In time it will be possible to move towards humidistat controlled heating but not quite yet.

Training of staff was carried out with regard to the humidifiers whose setpoint was turned down.

Outcome

Damagingly low relative humidity is now being avoided although there is still a little work to do on controlling solar thermal gain and ensuring the computer controls the temperatures correctly.

Site staff report that condensation on the windows is now only present in the coldest weather, suggesting that condensation in loft areas is also reduced or prevented.

Energy use is probably also lower but variations between the severity of winters makes this difficult to quantify yet.