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Libraries and archives house a majority of cultural heritage objects. The main purpose of libraries and archives is to provide suitable indoor climate conditions for preservation of their collection. In general, a large bulk of hygroscopic material is present which aids stable indoor climate conditions. Limited disturbances due to visitor presence occur in repositories and excludes to a large extent thermal comfort requirements. Library archives show potential of more tolerant setpoint control with permissible fluctuations. Little research is present into dynamic setpoint control and intermittent conditioning in libraries and archives. The aim of this study is to explore the possibility for intermittent conditioning and dynamic setpoint control on the energy impact and microclimate behavior in a library case study in The Netherlands. By means of a hygrothermal monitoring campaign from August 2016 to August 2017 the current indoor climate has been assessed under regular conditions and intervention periods (summer and winter) where the air handling unit was turned off. Both temporal and spatial measurements provided important information on microclimate behavior of the investigated repositories. A validated multi-zone model was used to investigate multiple setpoint strategies. Results show the potential of intermittent conditioning depending on whether dynamic setpoint conditions are used during operational hours (e.g. ASHRAE climate classes). If static conditions are applied, energy demand increases significantly, however, under dynamic setpoint control significant energy savings are possible. The lifetime multiplier is used to assess the chemical risks. The majority of investigated setpoint strategies show increased chemical risk.

Indoor climate fluctuations are regarded as one of the major risks for the emergence of damage in historical works of art. For a safe preservation of their art objects museums try to minimize this risk, which is typically done by imposing strict limitations on the indoor temperature and humidity conditions. The high energy demand resulting from this approach, however, undermines the aim of preeminent museums to execute a sustainable preservation strategy of their collections. A rational improvement of this aspect asks for detailed information on the history of museum objects, complemented by a thorough comprehension of the failure and deformation behaviour of museum objects under indoor climate fluctuations. Accordingly, in this paper the hygro-mechanical response of mock-ups of historical Dutch cabinet door panels made of oak wood is examined under several relative humidity variations. In specific, the mock-ups were subjected to (i) an instantaneous decrease of 40% relative humidity, (ii) eight successive, instantaneous drops of 5% relative humidity, and (iii) a varying relative humidity profile ranging between 35 and 71%. The shrinkage characteristics of mock-ups are translated to their damage susceptibility using an analytical hygro-mechanical bi-layer model. This model shows that restrained hygral shrinkage may originate from: (i) a difference in moisture content across the thickness direction of the panel, or (ii) a directional difference in the coefficient of hygroscopic expansions of structural components forming a coherent connection. The first type of shrinkage occurs in the outer regions of the panel thickness, while the second type of shrinkage takes place at the cleated ends. Further, by accounting for the age-dependency of the fracture strength of oak wood, a clear distinction can be made between the damage susceptibility of new door panels and historical door panels present in museum cabinets. The six main conclusions of the experimental study—conve

Climate-induced visual cracks or dimensional changes in historical art objects are aesthetically undesired. A thorough analysis of these aspects is essential for the development of adequate preservation strategies. For this purpose, in the present work full-scale experiments on mock-ups of historical cabinet doors were performed, and a numerical model was developed that can accurately simulate climate-induced damage development in oak wood. In contrast to what observation studies on historical museum objects indicate, the mock-ups showed no visible damage in terms of shrinkage cracks; a possible reason for this is that the local tensile strength of historical oak wood may be considerably lower than that of the new oak wood used for constructing the mock-ups. In the numerical model, the thermal and hygral responses were described by extended versions of Fourier's law of heat conduction and Fick's law of moisture diffusion. Discrete fracture is simulated by surrounding the continuum elements in a finite element model with interface elements equipped with a damage model. Preliminary numerical simulations give a good agreement with the solution of an analytical benchmark problem, and further show a realistic moisture hysteresis effect and damage pattern in the modelled sample.

Indoor temperature (T) and relative humidity (RH) are important for collection preservation and thermal comfort in museums. In the 20th century, the notion evolved that T and RH need to be stringently controlled, often resulting in excessive energy consumption. However, recent studies have shown that controlled fluctuations are permissible, enabling improved energy efficiency. Consequently, the thermal comfort requirements are increasingly important to determine temperature limits, but knowledge is limited. Therefore, a thermal comfort survey study and indoor measurements were conducted at Hermitage Amsterdam museum in Amsterdam, the Netherlands for one year, including: (1) monitoring of existing conditions (T = 21°C, RH = 50%); and (2) an intervention in which T is controlled based on an adaptive comfort approach (T = 19.5–24°C, RH = 50%). The results show that the thermal comfort of the existing conditions is far from optimum; visitors feel too cool in summer and slightly too warm in winter. The adaptive temperature limits were developed to improve thermal comfort significantly without endangering the collection, thereby saving energy. Furthermore, facilitating visitors to adapt their clothing may contribute to enlarging the temperature bandwidth and improve (individual) thermal comfort.

Recent museum studies have indicated the appearance of cracks and dimensional changes on decorated oak panels in historical Dutch cabinets and panel paintings. A thorough analysis of these damage mechanisms is needed to obtain a comprehensive understanding of the causes of damage and to advise museums on future sustainable preservation strategies and rational guidelines for indoor climate specifications. For this purpose, a combined experimental-numerical characterization of the fracture behaviour of oak wood of various ages is presented in this communication. Three-point bending tests were performed on historical samples dated 1300 and 1668 A.D. and on new samples. The measured failure responses and fracture paths are compared against numerical results computed with a finite element model. The discrete fracture behaviour is accurately simulated by using a robust interface damage model in combination with a dissipation-based path-following technique. The results indicate that the samples dated 1300 A.D. show a quasi-brittle fracture response, while the samples dated 1668 A.D. and the new samples show a rather brittle failure response. Further, the local tensile strength of the oak wood decreases with age in an approximately linear fashion, thus indicating a so-called ageing effect. Numerical simulations show that, due to small imperfections at the notch tip of the specimen, the maximal load carrying capacity under three-point bending may decrease by maximally 7 %. A comparison between a calibration of the experimental results by isotropic and orthotropic elastic models shows that the peak load is 10–13 % higher for the orthotropic elastic model. Finally, no significant dependence of the fracture toughness on the age of the oak wood and on the orientation of the fracture plane has been found. The strength and toughness values measured can be used as input for advanced numerical simulations on climate-induced damage in decorated oak wooden panels and panel painting

Firstly, this study presents an algorithm for setpoint calculation of museums' indoor temperature (T) and relative humidity (RH) integrating collection requirements according to ASHRAE and thermal comfort requirements according to adaptive temperature limits that follow from a one-year long comfort study in case study museum Hermitage Amsterdam. Secondly, this algorithm is implemented into a building energy simulation model to assess the energy impact for various cases: Five levels of museum indoor climate conditioning are applied to four building quality levels (ranging from a historical building to a purpose-built museum building) using weather data from six locations in Southern Europe. A validated building energy simulation model of museum Hermitage Amsterdam was adjusted to represent the four building quality levels, and technical-reference-year (TRY) weather data of six locations were used. The conclusions: The algorithm enables smooth control of hourly and seasonal adjustments in T and RH setpoints; the algorithm boosts energy efficiency due to more effective use of the permissible ranges of T and RH; improving the building quality quickly follows the law of diminishing returns due to internal heat and moisture loads; supposing to result in the same collection risk, subclass As (with seasonal adjustments, but smaller hourly fluctuations) is more energy efficient than subclass Ad (no seasonal adjustments, but larger hourly fluctuations) for most locations.

This study aims to improve the prediction accuracy of the rational standard thermal comfort model, known as the Predicted Mean Vote (PMV) model, by (1) calibrating one of its input variables “metabolic rate,” and (2) extending it by explicitly incorporating the variable running mean outdoor temperature (RMOT) that relates to adaptive thermal comfort. The analysis was performed with survey data (n = 1121) and climate measurements of the indoor and outdoor environment from a one year-long case study undertaken at Hermitage Amsterdam museum in the Netherlands. The PMVs were calculated for 35 survey days using (1) an a priori assumed metabolic rate, (2) a calibrated metabolic rate found by fitting the PMVs to the thermal sensation votes (TSVs) of each respondent using an optimization routine, and (3) extending the PMV model by including the RMOT. The results show that the calibrated metabolic rate is estimated to be 1.5 Met for this case study that was predominantly visited by elderly females. However, significant differences in metabolic rates have been revealed between adults and elderly showing the importance of differentiating between subpopulations. Hence, the standard tabular values, which only differentiate between various activities, may be oversimplified for many cases. Moreover, extending the PMV model with the RMOT substantially improves the thermal sensation prediction, but thermal sensation toward extreme cool and warm sensations remains partly underestimated. KEYWORDS: calibration, PMV, survey study, thermal comfort

This study presents a seven-step algorithm for hourly setpoint calculation of museums' indoor temperature (Ti) and relative humidity (RHi) integrating collection requirements (ASHRAE) and thermal comfort requirements. Moreover, building energy simulation results provide insight into the energy impact of five levels of museum indoor climate conditioning applied to four building quality levels (ranging from a historical building to a purpose-built museum building) using weather data from twenty locations throughout Europe. The five levels of indoor climate conditioning were calculated using the presented setpoint algorithm, a validated simulation model of museum Hermitage Amsterdam was adjusted to represent the four building quality levels, and technical-reference-year (TRY) weather data of twenty locations were used. The conclusions: The setpoint algorithm enables smooth control of seasonal adjustments, integrated with permissible short fluctuations of T and RH (according to ASHRAE classes); improving the building quality quickly follows the law of diminishing returns; supposing to result in the same collection risk, subclass Ad (no seasonal adjustments, but larger hourly fluctuations) is more energy efficient than subclass As (with seasonal adjustments, but smaller hourly fluctuations) for most locations; although class AA is more stringent than subclass As, class AA appears to require less energy than subclass As for some locations, due to efficiency differences of the humidification and dehumidification processes.

For buildings including temperature and humidity control, this study compares the energy prediction accuracy of a ZABES-model (Zone Air Building Energy Simulation) to an IBES-model (Integral Building Energy Simulation), which additionally includes models of the air handling unit (AHU) and controllers. Museum Hermitage Amsterdam served as a case study. For one year, measurements were performed in the main exhibition hall and its AHU. The ZABES-model was developed using heat air and moisture model for building and systems evaluation (implemented in MATLAB). The IBES-model was developed in Simulink and consists of the ZABES-model and models of AHU-components and controllers. Both models have been validated in detail. The IBES-model’s energy prediction errors are well within 10%. However, the ZABES-model underestimated the total annual energy consumption by 84%. Moreover, including occupants’ heat and moisture gains leads to realistic results using the IBES-model, but leads to unrealistic results using the ZABES-model. In conclusion, IBES-models are essential for reliable energy predictions of buildings including humidity control.

Climate induced damage in decorated oak wooden panels is considered to be a high risk for the preeminent museum collections. To advise museums on the development of future sustainable preservation strategies and to define rational guidelines for indoor climate specifications, climate induced physical and mechanical damage has been analysed in a collection study, experimental testing of mock-ups and by finite element modelling. The collection study consisted of the development of a comprehensive methodology to select objects of interest from the collection and analyse their condition using a combination of visual inspection and archival searches. Mock-up samples of wooden panels with representative structural elements were exposed to varying climate conditions in climate controlled rooms and monitored with state-of-the-art experimental mechanics equipment. Further the collection study and experimental testing were used to inform the development of a finite element model of crack growth under 3-point bending. The work was performed within the Cimate4Wood project, a multidisciplinary collaboration between conservators and scientists work. The paper presents the methodology of the museum study and results from the museum study, experimental testing and modelling., Structural Integrity & Composites

Museums are often located in historical buildings. To provide suitable housing in a historical building for a museum, these buildings are usually adapted to suit the need for object preservation through HVAC control. Maintaining a strict indoor climate and limiting short fluctuations in indoor temperature and indoor relative humidity reduces risk on objects. However, this also results in a rather high energy demand and therefore rather high costs. Previous research showed the energy conservation possibilities for a museum with state-of-the-art building envelope by adapting setpoint strategies. A gap in literature is present in applying these strategies in historical museum buildings. The aim of this study is to make use of different setpoint strategies to provide an indication of possible energy conservation for a historical museum building with respect to object preservation and thermal comfort. The method used consists of a measurement campaign to establish the current indoor climate and a simulation study with different climate control strategies. The simulation study provides possibilities to assess energy efficient control strategies with preservation of valuable museum objects in mind. The Amsterdam Museum serves as a case study during this research. With the data obtained during the measurement campaign, a hygrothermal zone-simulation model was calibrated. The results of the different climate control strategies present the energy saving potential for historical museum buildings. It is concluded that using the adaptive thermal comfort guideline for temperature during opening hours, and letting the collection criteria developed by ASHRAE's climate classes determine the relative humidity during the day, can save up to approximately 15% for a historical museum building without increasing the risk to the collection.

In the 20th century, museum indoor climates have been conditioned ever more strictly, sometimes beyond guidelines, allowing no fluctuations at all. Among other effects, this has led to excessive energy demands. At the start of the 21st century, interest has increased to condition the indoor climate more reasonable. This study assessed the energy impact of three levels of museum climate control: Reference (21 °C/50% RH, no permissible fluctuations), ASHRAE's Class AA, ASHRAE's Class A. Full-scale measurements were conducted in the museum Hermitage Amsterdam for one year. The results show that Class AA saved 49% and Class A saved 63% compared to the Reference setpoint strategy. Moreover, relaxing the climate specifications decreased hourly fluctuations, but increased daily fluctuations. It is highly likely that the overall degradation risk has not significantly changed for most artefacts.

Damage that might originate from climate fluctuations can be observed on decorated oak wooden panels in historical Dutch cabinets and panel paintings. A thorough analysis of the damage mechanisms is needed to obtain a comprehensive understanding of the causes of damage and to develop sustainable conservation strategies. For this purpose, the combined experimental and numerical characterisation of the fracture behaviour of historic and new oak wood is studied. Three point-bending tests are performed, and the measured failure responses and fracture paths are compared against results computed with a finite element model, in which discrete fracture behaviour is simulated with an interface damage model. The experimental and numerical results are in good agreement. The experiments show a quasi-brittle fracture response for the oldest samples and a more brittle fracture response for the new samples. In addition, the strength required for crack initiation along a radial-longitudinal fracture plane is higher than for a tangential-longitudinal fracture plane and the strength depends on the specimen size. Photographs and scanning electron microscopy photos illustrate that fibre bridging is more apparent for the oldest samples, and that the location of crack initiation is set by geometrical imperfections. Moreover, differences in density characterize the crack propagation path.

Building energy and occupant health concerns have increased the desire for variable, dynamic indoors and hence the interest in comfort of non-uniform and/or transient thermal conditions. An extended thermal comfort field study in the Hermitage Amsterdam museum afforded a unique opportunity to analyse evolving subjective perception of occupants, upon their moving indoors, over the time they spent in the museum. Visitors’ responses were grouped depending on how long they had been inside when they filled up the survey. The mean thermal sensation vote of each time group bore a strong correlation with their average time duration. For visitors who had been inside for 20 min or less, the thermal sensation vote had a significant relation with the outdoor temperature but not the indoor temperature. As visitors spent longer indoors, percentage of them feeling warm decreased and percentage of neutral or cool feeling increased. In tandem, the percentage of visitors preferring to be warmer also increased with time. Gender based differences in thermal sensation and preference also had a gradual and logical evolution with time. In an evidence of alliesthesial response, all the visitors inside for 20 min or less, accepted their thermal environment. The overall evidence suggests that visitor’s subjective perception of the thermal environment undergoes a distinct evolution during their first hour indoors.