Indoor air humidity of massive buildings and hygrothermal surface conditions

The indoor air humidity of massive buildings is important for the preservation of the building and its valuable interior parts. Open air gas infrared heating, for example, produces a lot of vapor, which may lead to high indoor air relative humidities and condensation on cold exterior walls and glazing. Due to (air) heating under cold winter conditions, the relative humidity drops and this may lead to very low indoor air relative humidities for interior objects such as church organs, resulting in cracking of wooden parts and other problems of drying out. Humidification would be a solution, but it may lead to high relative humidities near cold exterior surfaces. A method was developed for a graphical representation of the near surface relative humidity by measuring the surface temperatures as a function of time by infrared thermography and simultaneously determining the mean vapor pressure of the air. From these measurements, mold germination on indoor surfaces can be predicted in an early state, making use of a representation in so-called hygrographic pictures.</p

Experimental and numerical analysis of a novel display case design: case study of the renovated Anne Frank house

Many museums are housed in historic buildings, sometimes the building itself is part of the museum collection. Creating a stable environment by providing a nearly constant temperature and relative humidity at correct levels decreases the risk of object degradation. Maintaining this steady indoor environment, however, increases energy consumption and risks to the historic building. Museum display cases offer a solution to the mitigation of risks to which valuable objects may be subjected by providing an extra layer of protection to indoor climate fluctuations. The Anne Frank House is a historic house museum located in Amsterdam. The museum has undergone several renovations in the last years to deal with an increase in the number of visitors to over 1.2 million a year. The original diaries and other documents of Anne Frank are permanently on display in the Anne Frank House. With the recent refurbishment the possibility arose to design a new state-of-the-art display case. This study presents the results of the experimental research related to the design, performed in-situ. The temperature and relative humidity in the new exhibition space and inside the new display cases were monitored to gain insight into the hygrothermal behavior of these controlled environments. A complementary numerical study was performed to investigate effects of dynamic climate control of the exhibition gallery and climate conditions in the display case under various circumstances. Four main conclusions are presented in this paper. The investigated display case design is able to provide a stable relative humidity environment by means of silica gel, while using an active box-in-box climate control system to create stable temperature conditions. The inner case temperature depends on the temperature supplied by the display case air handling unit. Protocols must be in place in case of malfunction or failure of the climate control system of the display case. The air handling unit of the case needs to be shut off to create a passive environment for the objects on display until necessary actions are taken. Exhibition gallery set points can be less stringent when susceptible museum objects are on display in the display case. The environments are separated and provide an opportunity for energy saving set point strategies. The last conclusion drawn is that the numerical study provides valuable insight into imposing dynamic control of set points for temperature and relative humidity in the exhibition gallery and the effect on the display case environment