Rubens’ Ceiling at Banqueting House

For the last few decades, Hanwell has provided a unique environmental monitoring system to monitor the glorious and only surviving in-situ ceiling painting by Flemish artist, Sir Peter Paul Rubens in London’s glamorous Banqueting House. The series of three canvas paintings has lived through almost 400 years of alterations, restorations and preservation projects, including its removal and replacement during the second world war.

One of the toughest challenges facing the team from Historic Royal Palaces is being able to gain accurate temperature and humidity data on the canvas surface, where previous probe access issues made it very difficult to recalibrate the existing RH/T sensors just above and below the painted ceiling.  Hanwell Synergy which is now installed in the Banqueting House, allows the conservators to use calculation methods to translate temperature only readings to the associated local relative humidity, as temperature sensors are not prone to drift and will require no calibration over their lifetime.

The system works by where there are two groups of sensors (A and B). Group A is associated with the spaces above the ceiling and group B below. Each Group consists of several Temperature sensors and one T/RH sensor. The physical temperature sensors are dual devices fitted with remote probes: group A associated with Channel 1 and Group B associated with Channel 2 of each device. The incoming references from the T/RH transmissions (A and B) are processed by one of our controller units (CR3) with a unique program installed. The CR3 calculates the Partial vapor pressure in group A and Partial vapor pressure in group B, which values are derived from the calculated saturation vapour pressure at that temperature, multiplied by the measured relative humidity.

When a temperature-only sensor signal is received, then those temperatures and the related calculation partial pressures which will be combined to calculate the local RH and thus generate two outgoing composite T/RH signals. The local RH is calculated by using the relevant vapour partial pressure as calculated above, together with the calculated saturation partial pressure at the local temperature. These T/RH values are then displayed in Synergy for monitoring and reporting purposes, aiding the conservation team to preserve this fantastic artwork for many decades to come.