Toward Sustainable Environmental Control: Temperature and Humidity Control at the National Diet Library of Japan

Abstract

The key factor of the storage environment for prolonging the life of a library collection was once thought to be maintenance of the ideal level of temperature and humidity. Today, however, it is recognized that in regions with broad fluctuations in temperature, it is unrealistic to invest vast sums of money to maintain an even level of temperature and humidity in library stacks. Previously, the National Diet Library (NDL) Tokyo Main Library air conditioning system was operated throughout the year from 9:00 a.m. to 7:00 p.m. maintaining the stacks at 22C with a relative humidity (RH) of 55% until 2011. Following the discovery of large-scale mold infestation in the collection in 2007, however, the library reviewed its methods of temperature and humidity control.

This presentation introduces the NDL project to set up an environment management system for the whole NDL and improve its storage environment. It describes the NDL’s first experience of a large-scale mold infestation in 2007 and its efforts to eliminate mold the following year by monitoring temperature and humidity levels and regular inspection of the affected areas. Those efforts were continued through the establishment of an NDL-Wide Council for Environmental Control in 2009 and activities by its working group to counter the mold and high-humidity problem. The last part of the presentation describes changes in air conditioning operations since the Great East Japan Earthquake 2011 and remaining tasks in dust control.