Inside Relative Humidity Research Articles

Experimental Study on Insulation Performance and Condensation Characteristics of a Vacuum Insulated Glass Window

AbstrctThrough a mock-up test the surface temperature distribution and condensation characteristics were analyzed for a vacuum insulated glass (VIG) window, manufactured through an in-vacuum method, and compared with a double-glazed (DG) window. The outside air temperature was -21.2°C for a VIG window, at which the inside surface condensation begins to occur, given an inside air temperature of 20°C and an inside relative humidity of 50%; thus, given the typical weather conditions for Seoul, a VIG window is not likely to have condensation. The surface temperatures of the VIG window were found to be approximately 4 K–6 K higher than those of the DG window. In the case of the VIG window, the surface temperature of the center of glass is higher than that of the frame, because the vacuum insulated glass (VIG) has a superior insulation performance compared with the frame. However, the surface temperature of the edge of the vacuum insulated glass is lower than that of the frame, by approximately 0.9 K–1.5 K. Thus, to reduce heat loss and improve condensation resistance, measures to reduce heat loss at the glass connection should be established and frames should be utilized that have insulation performance equal to or better than VIG.

Evaluation of a new heat transfer and evaporative design for a zero energy storage structure

A passive evaporative zero energy storage structure (ZESS) has been developed as a low cost and eco-friendly cooler for storing perishable fruit and vegetables with moderate respiration rates. Evaporation is influenced by weather conditions (air temperature, relative humidity, and the direction and speed of the outside air) and the porous nature of the heat exchanging and evaporative media (pore space of gravel stone with thermal–hydraulic conductivity and vapor diffusion properties of the porous medium). The ZESS consists of two heat exchanging media (outside wall made of porous volcanic lava stone and inside wall made of solid clay brick), one evaporative medium (sand–zeolite–gravel stone), and one natural humidifier (detachable clay water tank) inside the storage area. The results obtained from the performance tests revealed that the temperature inside the ZESS was 15°C lower than the outside air temperature, while the inside relative humidity was 20% higher than the outside relative humidity. As a result, the shelf life of stored tomato and eggplant inside the ZESS increased from 7 to 19days and 4 to 9days, respectively, with maximum watering of 29Lday−1. Thus, a ZESS provides an excellent means of short-term preservation of fruit and vegetables soon after harvest.

Use of insect exclusion cages in soybean creates an altered microclimate and differential crop response

Insect exclusion cages are commonly used in agricultural and ecological studies to examine plant-insect interactions in a field setting while maintaining control over insect populations. However, these insect cages can unintentionally alter the climate inside of the cage and impact plant physiology, growth and yield as well as insect populations. This can subsequently affect interpretations of experimental results obtained from caged experiments. To address this concern, we measured meteorological variables in conjunction with soybean physiology, growth, and yield over a two-year period. In a 2011 field study in southern Wisconsin, we compared photosynthetic rates, leaf area index (LAI), soil environmental conditions, and various components of yield for plants grown inside and outside of an industry standard insect cage (Lumite 32×32 mesh). Inside of cages, several variables were higher (P<0.05) including surface (0–6cm) soil moisture (38%), stomatal conductance (42%), and total plant biomass (30%), while LAI was 20% lower (P<0.001) inside of the cages. During the 2012 growing season, we measured wind speed, wind gusts, solar radiation, air temperature and relative humidity inside of cages compared to open field conditions. We found that wind speed and solar radiation were 89% and 42% lower, respectively, and air temperature, relative humidity and vapor pressure deficit were not significantly affected. There was also a significant (P<0.0001) effect of the time of day on differences in wind speed and radiation between cages and open field plots. Our findings suggest that commonly used insect cages significantly alter the microclimate inside of the cage, and create a radiation regime in which the amount of direct and diffuse radiation received by plants is altered compared to the open field. Plant physiological processes and growth are affected by these environmental changes, adding a confounding factor when comparing caged to open field plants. Because the effects are likely a function of the type of cage, and mesh size and color, we recommend that future studies more thoroughly measure the microclimate for a variety of common cage types used in experiments.

Design, Development and Performance Evaluation of an on-Farm Evaporative Cooler

The portable evaporative cooler was designed for storage of 50 kg fresh fruits having overall diamentions of 1220 x 860 x 787 to study the performance of an on-farm evaporative cooler with the effect of different filling materials viz., coconut coir, saw dust + gunny bag, ECC cool pad, wala sheet and gunny bag. Selection of filling material was based on the cost, water holding capacity, rate of evaporation of water from filled material and easy availability. Sapota (Cv. Kalipatti) fruits were stored in an on-farm evaporative cooler for 16 days. The effect of filling materials on Physiological weight loss (PLW), inside temperature, inside relative humidity and cooling efficiency of five filling materials were studied. The weight loss varied between 2.50 to 13.29, 14.96, 15.37, 15.36 and 15.20% in coconut coir, saw dust + gunny bag, ECC cool pad, walasheet and gunny bag, respectively. The mechanical test such as cooling efficiency for each filling material was determined and it was recorded as 90%, 54%, 38%, 70% and 79% for coconut coir, saw dust + gunny bag, ECC cool pad, walasheet and gunny bag respectively. Minimum inside temperature of 16.5 to 17.20C and maximum inside relative humidity of 97 to 90% was recorded in coconut coir of an on-farm evaporative cooler when ambient temperature was 27.660C and ambient relative humidity was 51%.The maximum storage life of 16 days was found in coconut coir. Coconut coir was performed better when compared with other filling material. It was most economical filing material over the other filling materials.

PREDICCIÓN SIMULTÁNEA DE TRES VARIABLES CLIMÁTICAS EN UN INVERNADERO

The complexity of the greenhouse crop production, together with the environmental variables interaction, has encouraged the development of various models to predict and simulate variables in order to manage the greenhouse in an efficient way. One of the models that has been used successfully in prediction is the Artificial Neural Networks (ANN). The purpose of this paper was to predict the greenhouse inside conditions based on the outside environmental conditions. A data set of 19,960 values was used from the experimental greenhouse naturally ventilated, without CO2 enrichment, at Humboldt University of Berlin, from August 16 to October 24, 2007 and include the external variables: solar radiation, air temperature, wind velocity, relative humidity, and carbon dioxide concentration, heat transfer by heating system and ventilation opening; and the internal variables: air temperature, relative humidity and CO2 concentration. A three layer artificial neural network was trained and tested and validated using back conjugate gradient back propagation algorithm with a hyperbolic tangent function and momentum algorithm. The predicted values obtained from the ANN model were close to the measured values. These results showed that ANN model learnt the behavior and interactions between all variables. The aid of the ANN model developed was the simultaneous prediction of temperature, relative humidity and CO2 concentration inside of the greenhouse, which will be helpful in checking the accuracy of sensor readings.

Effect of internal curing on internal relative humidity and shrinkage of high strength concrete slabs

In the paper, the moisture content, in terms of relative humidity, inside of high strength concrete slab, with and without addition of pre-soaked lightweight aggregate (PSLWA), exposed to normal indoor environment is investigated by continually measuring the interior humidity of concrete immediately after slab casting until 28days. The effects of internal curing on the developments of internal relative humidity and free shrinkage in high strength concrete slab are analyzed. The experimental results show that the internal relative humidity of high strength concrete decreases with concrete age since casting. The developing tendency of the relative humidity inside of concrete with age follows a vapor-saturated stage with 100% relative humidity (stage I) and a stage that relative humidity gradually decreases (stage II). A humidity gradient along the thickness of slab exists in early age high strength concrete. As PSLWA is added, the reduction rate of interior humidity in stage II is obviously reduced and the reduction trend with age changes from non-linear pattern to almost linear pattern. The duration of the internal humidity-saturated stage I is noticeably prolonged by addition of PSLWA. The humidity gradient together with the corresponding shrinkage gradient along the thickness of the slab is reduced also. The highest reduction on internal humidity at 28days since casting in high strength concrete slab is changed from 46.5% to 26.2% with a medium PSLWA addition ratio, and finally to 7.9% with a high PSLWA addition level. Within present addition range, the more the PSLWA added, the stronger the above positive internal curing effects.

Diurnal and Night Change in Greenhouse's Microclimatic Condition

In modern greenhouses, measurements of climate conditions are required to give the grower a better understanding on how each factor affect growth and how to achieve maximal crop productiveness. The measurements and resultant optimal conditional adjustments enable the grower to improve productivity and achieve maximum costs and energy savings. Data of climate parameters were collected and analyzed to determine night and diurnal change of solar radiation, air temperature and humidity inside greenhouse, temperature and humidity difference between inside and outside air of a greenhouse, the temperature difference between the soil and the inside air and the transparency behaviour of the covering material. Results shows that diurnal solar radiation is higher outside than inside of greenhouses as expected. The maximum solar radiations were about 742 W/m2and 545 W/m2 for both outside and inside of the structure respectively towards noon. However, the ratio of solar radiation inside to solar radiation outside the greenhouse ratio was quite constant throughout the daytime at values of 0.8 – 0.7. There was lower temperature inside the greenhouse during the night or at the sunset while in the daytime the inside temperature was higher with a steady increase in the difference between the two up to noon time. Also, there was clear difference between inside relative humidity and outside relative humidity in the night and day up to 11:00 AM. Opening the screens for ventilation was used to control or regulate the microclimate condition of the greenhouse. Soil temperature was higher/lower than air temperature during night/day indicating on the possibility to use the soil as a heat buffer. Keywords: Greenhouses, relative humidity, temperature, solar radiationNigerian Journal of Technological Research, 8(2), 2013

Dynamic optimization of inside temperature of Zero Energy Cool Chamber for storing fruits and vegetables using neural networks and genetic algorithms

A ‘Zero Energy Cool Chamber (ZECC)’ has been developed for storing fruits and vegetables from the viewpoints of low cost and energy savings. Adding water to a filler between the outer and inner brick walls and shade curtains is effective way to reduce the inside temperature of a ZECC. The objective of this study was to minimize the inside temperature by controlling the watering using an intelligent optimization technique (IOT) combined with neural networks (NN) and genetic algorithms (GA). The objective function was given by the average value of the inside temperature for one day. For dynamic optimization, the control process (24h) was divided into 8 steps, and the optimal value (8-step ON–OFF intervals) of watering was obtained using NN and GA. In this method, dynamic changes in the inside temperature of the ZECC, as affected by the watering strategy, outside temperature and inside relative humidity conditions, were first identified using NN, and then the optimal value, which minimized the objective function, was determined through simulation of the identified NN model using GA. The average inside temperature for this optimal control was 4°C lower than that for the continuous watering for 24h, and was also 7.5°C lower than that for no watering. The ZECC with the optimal watering strategy extended the shelf-life of tomato from 7 to 16days. Thus, it was concluded that a ZECC optimized by using NN and GA is useful for storing tomato with no electric energy.

Geological and Geotechnical Parameters Controlling Wall Paints Detachment at Selected XXVI Dynasty Tombs, Bahariya Oasis, Egypt

Detection and semi-quantification of weathering processes acting on a given archaeological site is more than half way of stone's conservation to survive for longer decades or centuries revealing non-recovered part of nations' history. Bahariya Oasis in the heart of the Western Desert of Egypt has much recently discovered archaeological sites almost related to 26 th Dynasty i.e. 2650 YBP. It still requires detailed studies on it regarding several fields of research among those are: weathering processes and intensity on wall paints of these sites. The main aims of the current study is to find out the impact of bedrock's iron oxide content on wall paints of the structures excavated through it, and to semi-quantify damage category at the two , Badi Eshtar and Bannantiu, tombs under investigation that are related to 26 th Dynasty at Bahariya Oasis. Detailed field survey including reporting and measuring weathering features' dimensions as well as air temperature and relative humidity inside and outside these sites in Winter and Summer Seasons have been conducted. Then, laboratory investigations including SEM, XRF, MIP and Ultrasonic waves have been applied on light and dark brown facies at these sites. The net result is moisture condensation inside these tombs particularly in summer as well as micro-pore size distribution, controlled by iron oxide concentration in this bedrock, with the aid of clay content resulted in rock's weathering ranging from Moderate to Very severe damage category at Badi Eshtar Tomb, and from Severe to Very Severe at Bannantiu Tomb. Urgent controlling air temperature and relative humidity inside such excavations at Bahariya Oasis, and organized plan of paint's restoration are recommended for such unique rock art in the Western Desert of Egypt.

A COMPREHENSIVE STUDY ON DIFFERENT METHODS FOR AIR EXCHANGE RATES MEASUREMENT IN A NATURALLY VENTILATED DAIRY HOUSE

The major problem of natural ventilation is the lack of accurate, continuous and online measuring and controlling techniques for air exchange rates (AER) which is crucial for the quantification of gaseous emissions. Therefore, this papers aims at comparing four measurement methods and to recommend thereof one method for further developments. Thirty six experiments were performed to study the AERs in a naturally ventilated dairy barn through four summer seasons and three winter seasons. The AERs were determined using moisture (H2O) balance, heat balance (HB), CO2-balance and tracer gas technique (TGT). The statistical analyses were correlation analysis, regression model, ANOVA model and t-test. Continuous measurements of CO2 concentrations, temperature and relative humidity inside and outside the building were performed. The H2O-balance showed reliable results through winter seasons and slightly acceptable results through summer seasons. The error sources of H2O-balance are: the difference between the internal and external humidity levels which depend in turn on the accuracy of the used temperature-humidity sensors and their locations, the correctness of the used factors (e.g. the moisture produced by one cow and per mass unit), and the accuracy of the calculations of the humidity ratios. The HB showed acceptable results to some extent through summer seasons and unsatisfactory results through winter seasons. The error sources of HB are: the calculations accuracy of the net area of the different building components and the determination of the relevant overall heat transfer coefficients, the temperature difference which depends in turn on the accuracy of the used temperature-humidity sensors and their locations, and the sensible heat produced by the animals which depends on the physiological changes of the animals. The CO2-balance showed unexpected high differences to the other methods in some cases. The error sources of CO2-balance are: the use of calculation models for metabolic energy, the amount of CO2 produced per energy unit, the quantity of CO2 produced emitted from manure, variations of ambient temperatures and the location of CO2 measuring points. The TGT showed reliable results compared to HB, H2O-balance and CO2-balance. Therefore, the TGT should be further developed, where it delivers comparable results and is independent on the physiological parameters. The airflow rates (AFRs), subject to TGT, were 0.12 m3 s-1 m-2, 1.15 m3 s-1 cow-1, 0.88 m3 s-1 LU-1 (LU is livestock unit of 500 kg), 395 m3 s-1 and 470 kg air s-1 through summer seasons, and 0.08 m3 s-1 m-2, 0.83 m3 s-1 cow-1, 0.64 m3 s-1 LU-1, 275 m3 s-1 and 328 kg air s-1 through winter seasons. The AERs were 37, 81, 63 and 62 h-1 through summer seasons, and 40, 143, 61 and 39 h-1 through winter seasons subject to H2O-balance, HB, CO2-balance and TGT, respectively.

Shrinkage and Interior Humidity of Concrete under Dry–Wet Cycles

The dry–wet cycle is one of the aggressive environmental conditions suffered by concrete. This article focuses on the experimental study and theoretical simulation of shrinkage of concrete during dry–wet cycles. The experimental results show that the interior relative humidity of concrete is periodically changed during dry–wet cycles. As concrete undergoes wetting, a fast increase in interior humidity takes place in a short time and then the relative humidity reaches a stable level, which depends on the strength of concrete or on the water-to-cement ratio of concrete. In contrast, as concrete undergoes drying, the interior relative humidity does not drop immediately but decreases in a gradual manner. Accordingly, the shrinkage of concrete during dry–wet cycles is also periodically changed, exhibiting shrinkage as drying and expansion as wetting. Based on the experimental findings, a model for shrinkage predictions of concrete during dry–wet cycles is developed. The model is based on the capillary tension created in capillary pores in concrete and uses the interior relative humidity (RH) as the driving parameter for shrinkage predictions. The model predictions on the development of shrinkage strain under plastic sealed and dry–wet conditions are compared with experimental results and a reasonable agreement was found.

수목의 장기 기후변화 연구시설: CO2폭로용 상부 개방형 온실

The open-top chamber (OTC) system is designed for long term studies on the climate change impact on the major tree species and their community in Korea. In Korea Forest Research Institute (KFRI), the modified OTC system has been operating since September 2009. The OTC facility consists of six decagon chambers (10 meters in diameter by 7 meters high) with controlled gas concentration. In each chamber, a series of vertical vent pipes are installed to disperse carbon dioxide or normal air into the center of the chamber. The OTC is equipped with remote controlled computer system in order to maintain a stable and elevated concentration of carbon dioxide in the chamber throughout the experimental period. The experiment consisted of 4 treatments: two elevated levels ( and ambient ) and two controls (inside and outdoors of the OTC). Average operational rate was the lowest (94.2%) in June 2010 but increased to 98% in July 2010 and was 100% during January to December 2011. In 2010~2011, concentrations inside the OTCs reached the target programmed values, and have been maintained stable in 2011. In 2011, concentrations of 106%, 100% and 94% of target values has been recorded in control OTC, -enriched OTC and -enriched OTC, respectively. With all OTC chambers, the difference between outside and inside temperatures was the highest () at 10 am to 2 pm. Temperature difference between six OTC chambers was not detected. The relative humidity inside and outside the chambers was the same, with minor variations (0~1%). The system required the highest amount of for operation in June, and consumed 11.33 and 17.04 ton in June 2010 and 2011, respectively.

EVALUACIÓN DE UN MODELO PARA ESTIMAR LA TEMPERATURA Y HUMEDAD RELATIVA EN EL INTERIOR DE INVERNADERO CON VENTILACIÓN NATURAL

A weather model was evaluated to estimate the hourly time temperatura and relative humidity inside of a zenithal ventilated type green-house, as a function of the weather outside of the greenhouse. The study was carried out during the Winter of 2008-2009, in a comercial greenhouse with tomato production, located at Tlahualilo, Durango, Mexico. The model considered the effect of natural ventilation. The results of the evaluation for two non consecutive days showed a good estimation of the air temperature, and a reasonable good estimation of relative humidity. Some adjustments are still required to improve the quality of the model.ADDITIONAL KEYWORDS: Energy balance, water vapor balance, solar radiation.

Interior Relative Humidity of Normal- and High-Strength Concrete at Early Age

AbstractThe moisture content in the concrete pores is a critical parameter for most of the degradation processes suffered by concrete, for example concrete shrinkage and related cracking. In the present paper, the development of internal relative humidity of a concrete slab at an early age was investigated by applying the temperature and humidity combined digital sensor. The experimental results show that the internal relative humidity of concrete is reduced with concrete age. The general law of the development of relative humidity inside of concrete can be described by a vapor-saturated stage with 100% relative humidity (Stage I) followed by a stage that the relative humidity gradually reduced (Stage II). The length of Stage I and the magnitude of relative humidity in Stage II are greatly influenced by the strength of concrete and the location in concrete. A humidity gradient along the thickness of the concrete specimen existed at an early age. The humidity gradient in high-strength concrete (C80) is mor...

Moisture balance and tracer gas technique for ventilation rates measurement and greenhouse gases and ammonia emissions quantification in naturally ventilated buildings

Experiments were performed to study the ventilation rates in a naturally ventilated animal building through four summer seasons and three winter seasons. The ventilation rates were determined using moisture (H 2O) balance, tracer gas technique (TGT) and CO 2-balance. The statistical analyses were correlation analysis, regression model and t-test. Continuous measurements of gaseous concentrations (NH 3, CH 4, CO 2 and N 2O), temperature and relative humidity inside and outside the building were performed. The H 2O-balance showed reliable results through winter seasons and acceptable results to some extent through summer seasons. The CO 2-balance showed unexpected high differences to the other methods in some cases. The TGT showed reliable results compared to H 2O-balance and CO 2-balance. The air exchange rates (AERs) were 37.2, 61.6 and 63 h −1 through summer seasons, and 40.3, 38.9 and 60.5 h −1 through winter seasons subject to H 2O-balance, TGT and CO 2-balance, respectively. The emission rates through summer seasons, subject to TGT, were 191, 855, 73,877 and 45.6 g d −1 AU −1; and through winter seasons were 88, 463, 55,976 and 47.3 g d −1 AU −1, for NH 3, CH 4, CO 2 and N 2O, respectively.

Interior Humidity of Concrete under Dry-Wet Cycles

The dry-wet cycle is one of the aggressive environmental conditions suffered by concrete. This paper focuses on the experimental study and theoretical simulation of water distribution in normal- and high-strength concrete through dry-wet cycles. The experimental results show that under dry-wet cycles, the variation in the interior humidity of concrete occurs mainly within a certain depth from the drying/wetting face. This depth is called the influencing depth under dry-wet cycles. The interior relative humidity of concrete within the influencing region periodically changes under dry-wet cycles. As concrete undergoes wetting, a fast rise in interior humidity occurs in a short time, and finally the relative humidity reaches approximately 100%. By contrast, as concrete undergoes drying, the interior relative humidity does not drop immediately, but in a more gradual manner. In the modeling, a model taking both cement hydration and moisture diffusion into account synchronously is used to simulate the moisture distribution in concrete under dry-wet cycles. A comparison between model and experimental results concludes that the model can predict the moisture distribution in concrete, as well as its variations, through dry-wet cycles.

Effect of Limestone Powder on Autogenous Shrinkage of Concrete

The effect law and mechanism of limestone powder on autogenous shrinkage of concrete was studied. The results indicate that limestone powder accelerates autogenous shrinkage speed of concrete on which effect of fineness is little, and limestone powder reduces autogenous shrinkage which decreases with the increase of fineness. The change law of autogenous shrinkage of concrete is consistent with that of chemically combined water of paste. Autogenous shrinkage of concrete is also divided into 2 stages according to the initial vapor saturated stage and subsequent reduction stage of interior relative humidity, with both showing a good linear correlation at each stage.

Controlling Condensation Through the Use of Active and Passive Glazing Systems

Abstract Special building occupancies, those with a high interior relative humidity, have a specific set of performance requirements to control condensation for exterior window and curtain wall systems. High levels of humidity, if not properly accommodated by glazed exterior wall systems, can result in condensation on and within glazing systems and adjacent construction. The performance of glazing has typically been viewed and analyzed based on overall system performance that generally results in a set of values that do not apply to project specific applications. With this approach, important aspects of a system, as applied to specific buildings, are often overlooked. In this circumstance, the result too often is unacceptable levels of condensation. Unfortunately, many within the design, manufacture, and construction communities do not fully understand the importance of treating each building for the unique set of conditions that it is, and the resultant consequence of not analyzing and treating each humidified building as a unique set of materials, systems, and environmental conditions. Similarly, the analysis methods and tools necessary to predict and prevent condensation are even less familiar within the design and construction industry. As a result, deficient systems and materials may often be installed in these applications, resulting in failures ranging from minor inconvenience to complete loss of service. There are, however, methods that can be used to reduce or eliminate such problems. This paper describes methods and procedures that can be utilized to understand and identify the performance levels required for high humidity spaces and analysis methods (including computer modeling) to predict performance of systems and materials, and this paper also describes both active and passive technologies that have been successful in meeting these needs. Passive design, through the use of high performance glazing, and active technologies, such as heat tracing and heated glass, are considered. Benefits, risks, and appropriate uses of each are identified. Examples are included to illustrate these approaches.

Pseudo bond graph model of coupled heat and mass transfers in a plastic tunnel greenhouse

In greenhouses, models built are classified into two kinds; heterogeneous approaches based on computational fluid dynamics (CFD) codes and homogeneous one based on heat and mass balance equations. Bond graph modelling was not seriously introduced in greenhouse modelling in spite of the concordance of the energetic based approach of bond graphs with the nature of the greenhouse plant. In this research work, a pseudo bond graph model of a greenhouse was elaborated to simulate temperature and relative humidity inside. The model proposed is an energetic lumped approach which describes coupled heat and mass transfers in a plastic tunnel greenhouse. This model includes convection, evaporation/condensation phenomena, air change flow and soil heat and mass transfer. Multiport (3 ports) bond graph elements are introduced to describe the state of the two elements (dry air and water vapor) fluid. New bond graph schemes are used to characterize the coupling effect between heat and mass transfer, and for modelling free evaporation/condensation mechanism. Big leaf assumption was used to model the canopy. New boundary layer elements are added in the model, these elements allow a separation of the different phenomena inside greenhouse and thus a simplification of the modelling task. The practical results obtained from an experimental tunnel greenhouse are used here as validation elements for the greenhouse bond graph model. A good correlation is observed between measured and predicted samples.

Sandstone Chamber Humidity and Tourism in Petra, Jordan

Comprehensive interior and exterior humidity measurements were made in Petra's most celebrated structures, al-Khazneh and Urn Tombs, in tandem with data on visitor number and frequency. Small tourist groups entering the chambers caused interior relative humidity increases of between 5 and 15%. Statistical correlations of determination (r2) also revealed that the most significant relationships between visitor number contributions and chamber humidity occurred fifteen minutes after the visit. Correlations increased dramatically when the tourist numbers and relative humidity were viewed simultaneously (r2=0.007, 0.136), and then compared to measurements taken with a fifteen minutes lag time (r2=0.707, 0.895). These relationships indicate that it takes ten to twenty minutes for human respiration and transpiration to contribute to relative humidity in chambers of this volume (2,000–3,600 m3). Wall measurements found interior surfaces to have receded from visitor-induced abrasion (such as touching and leaning) by up to 40 mm during the 50–100-year era of increased tourism in the region. It is also indicated that a 4 × 3 m wall section has lost 500,000 cm3 of sandstone over these past 100 years, between 0.5 to 2 m above the floor, indicating surface recession from human contact where visitors commonly lean, touch or rest.