Challenging the assumptions for thermal sensation scales Schweiker, Marcel; Fuchs, Xaver; Becker, Susanne ...
Building research and information : the international journal of research, development and demonstration,
07/2017, Volume:
45, Issue:
5
Journal Article
Peer reviewed
Open access
Scales are widely used to assess the personal experience of thermal conditions in built environments. Most commonly, thermal sensation is assessed, mainly to determine whether a particular thermal ...condition is comfortable for individuals. A seven-point thermal sensation scale has been used extensively, which is suitable for describing a one-dimensional relationship between physical parameters of indoor environments and subjective thermal sensation. However, human thermal comfort is not merely a physiological but also a psychological phenomenon. Thus, it should be investigated how scales for its assessment could benefit from a multidimensional conceptualization. The common assumptions related to the usage of thermal sensation scales are challenged, empirically supported by two analyses. These analyses show that the relationship between temperature and subjective thermal sensation is non-linear and depends on the type of scale used. Moreover, the results signify that most people do not perceive the categories of the thermal sensation scale as equidistant and that the range of sensations regarded as 'comfortable' varies largely. Therefore, challenges known from experimental psychology (describing the complex relationships between physical parameters, subjective perceptions and measurement-related issues) need to be addressed by the field of thermal comfort and new approaches developed.
Full text
Available for:
BFBNIB, IZUM, KILJ, NUK, PILJ, SAZU, UL, UM, UPUK
•Unsteady-state calculation of human-body exergy consumption rate (Ex) is applied.•Relationships between Ex, thermal sensation and thermal acceptance votes are shown.•A strong linear relationship on ...warm and cold side exists between Ex and sensation.•Linear relationships were found between Ex and acceptance.•A lower Ex is subjectively assessed by a higher thermal acceptance.
Few examples studied applicability of exergy analysis on human thermal comfort. These examples relate the human-body exergy consumption rate with subjectively obtained thermal sensation votes and had been based on steady-state calculation methods. However, humans are rarely exposed to steady-state thermal environments. Therefore, the first objective of the current paper was to compare a recently introduced unsteady-state model with previously used steady-state model using data obtained under both constant and transient temperature conditions. The second objective was to explore a relationship between the human-body exergy consumption rate and subjective assessment of thermal environment represented by thermal sensation as well as to extend the investigation towards thermal acceptability votes. Comparison of steady-state and unsteady-state model showed that results from both models were comparable when applied to data from environments with constant operative temperature. In contrast, when applied to data with temperature transients the prediction of particular models differed significantly and the unsteady-state model resulted in better prediction of mean skin temperature. The results of the present study confirmed previously indicated trends that lowest human body exergy consumption rate is associated with thermal sensation close to neutrality. Moreover, higher acceptability was in general associated with lower human body exergy consumption rate.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
As the infrastructure grows, space on the surface in the urban area is diminishing, and the view of the builders is increasingly moving underground. Implementation of underground structures, however, ...presents a number of problems during construction. One of the primary side effects of tunnel excavation is vibration. These vibrations need to be monitored for potential damage to structures on the surface, and this monitoring is an integral part of any such structure. This paper brings an original pilot comparative study of standard seismic instrumentation with experimentally developed fiber-optic interferometric and acoustic systems for the purpose of monitoring vibration caused by the blasting operation. The results presented show that systems operating on physical principles (other than those previously used) have the potential to be an alternative that will replace the existing costly seismic equipment. The paper presents waveform images and frequency spectra from experimental measurements of the dynamic response of the rock environment, due to blasting operation performed shallowly during the tunnel excavation of a sewer collector. In the time and frequency domain, there is, by comparison, significant agreement both in the character of the waveform images (recording length, blasting operation timing) and in the spectra (bandwidth, dominant maxima).
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This article reviews and analyzes the approaches utilized for monitoring cutting tool conditions. The Research focuses on publications from 2012 to 2022 (10 years), in which Machine Learning and ...other statistical processes are used to determine the quality, condition, wear, and remaining useful life (RUL) of shearing tools. The paper quantifies the typical signals utilized by researchers and scientists (vibration of the cutting tool and workpiece, the tool cutting force, and the tool’s temperature, for example). These signals are sensitive to changes in the workpiece quality condition; therefore, they are used as a proxy of the tool degradation and the quality of the product. The selection of signals to analyze the workpiece quality and the tool wear level is still in development; however, the article shows the main signals used over the years and their correlation with the cutting tool condition. These signals can be taken directly from the cutting tool or the workpiece, the choice varies, and both have shown promising results. In parallel, the Research presents, analyzes, and quantifies some of the most utilized statistical techniques that serve as filters to cleanse the collected data before the prediction and classification phase. These methods and techniques also extract relevant and wear-sensitive information from the collected signals, easing the classifiers’ work by numerically changing alongside the tool wear and the product quality.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A Demand-controlled ventilation (DCV) has been recognized as a promising solution for decreasing energy consumption while ensuring good Indoor Air Quality (IAQ) in buildings. However, its application ...in the residential sector has increased first recently. Implementation of DCV systems brings the problem related to assessing their performance, not only in the view of energy savings but also in the ability to ensure IAQ. The objectives of this paper were to introduce a multicriteria performance-based approach for the evaluation of residential ventilation systems with CONTAM airflows simulations; illustrate its applicability to three DCV strategies in the context of renovated apartment buildings in Denmark and challenge the minimal background airflow requirements anchored in the Danish building code.
Our performance-based approach allows assessing ventilation performance regarding IAQ (CO
2
, humidity, PM
2.5
, and formaldehyde-based indicators), energy consumption, and ventilation heat loss.
Our results show that DCV strategies can improve IAQ while decreasing airflows. For example, application of DCV reduced the cumulative indicator of occupant exposure to formaldehyde, IHCHO by 6 to 28 %, compared to the constant-airflow system. For humidity controlled mechanical exhaust ventilation, the heat loss can be reduced up 51%.
Inappropriate indoor environmental quality (IEQ) conditions are shown to reduce occupants’ satisfaction, wellbeing and performance. Therefore, it is crucial to provide an excellent classroom IEQ in ...order to minimize learning loss among students. This study determines the effect of different thermal and indoor air quality (IAQ) conditions in a classroom on students’ satisfaction, study engagement and cognitive performance. Three data collection campaigns were performed in a university classroom. Data collection consisted of (1) continuous IEQ monitoring (i.e., temperature, relative humidity, CO
2
, …), (2) frequent assessments of students’ satisfaction with IEQ and study engagement via here-and-now surveys, and (3) evaluations of students’ memory and processing speed. The IEQ conditions were varied by adapting (1) a room temperature setpoint between 18°C to 26°C and (2) a CO
2
-setpoint between 500 ppm and 1000 ppm. A mixed-effects regression analysis on the collected data showed statistically significant relationships between students’ study engagement and the room temperature trend, air enthalpy, relative humidity and TVOC-concentrations in the classroom. The addition of data on students’ satisfaction with IEQ only improved a minority of model fits. A statistically significant difference in students’ memory was found between test conditions. However, a randomized experimental design is needed to determine the relationship between the classroom IEQ and students’ cognitive performance.
Occupants can provide valuable feedback on the indoor environmental quality of buildings. Research on occupant voting systems (OVS) has demonstrated that apps or electronic devices can act as viable ...tools for collecting long-term feedback from occupants. However, previous research has only to a limited extent explored occupants’ interaction with OVS and the impact it might have on the reliability of the collected feedback. The present paper presents three case studies on applying a tangible OVS, denoted TiAQ, to collect feedback on thermal and indoor air quality (IAQ) in office spaces. The main objective of the present study was first to explore occupants’ interaction with TiAQ and their motivation. Second, identifying whether feedback collected with TiAQ could represent occupants’ comfort and discomfort with the thermal environment and IAQ. Thirdly, identifying challenges related to occupants’ interaction with TiAQ that might affect the representativeness of collected feedback. The present study was conducted at three office buildings in up to 7 months and demonstrated that TiAQ was suitable for collecting long-term feedback on occupants’ comfort and discomfort with the thermal environment. On average, one vote was cast per day per occupant. Additionally, in one of the office buildings, 60% of occupants reported to have interacted with TiAQ daily or weekly when, e.g., passing the device going to/from the office spaces. Occupants’ expectations of TiAQ and getting “feedback on feedback” need to be further addressed to identify ways to sustain occupants’ long-term use of the device and reduce “ill-willed” interactions.
Airtight energy-efficient buildings of today need efficient ventilation to secure high indoor air quality. There is a need for affordable and reliable sensors to make demand control available in a ...broad range of ventilation systems. Low-cost metal oxide semiconductor (MOS) volatile organic compound (VOC) sensors offer such a possibility, but they are usually non-selective and react to broad range of compounds. The objective of the present paper was to use cluster analysis to assess the ability of five commercially available MOS VOC sensors to detect pollutants in a residential setting. We studied three scenarios: emissions from people (human bioeffluents), furnishing materials (linoleum), and human activity (surface cleaning with spray detergent). We monitored each scenario with five MOS VOC sensors and a proton-transfer-reaction–time-of-flight mass spectrometer (PTR-ToF-MS). We applied an agglomerative hierarchical clustering algorithm to evaluate the dissimilarity between clusters. Four of the five tested sensors produced signals in agreement with the concentration patterns measured with the PTR-ToF-MS; one sensor underperformed in all cases. Three sensors showed a very similar performance under all emission scenarios. The results showed that the clustering could help in understanding whether a particular sensor matched the intended emission scenario.
Application of the exergy concept to research on the built environment is a relatively new approach. It helps to optimize climate conditioning systems so that they meet the requirements of ...sustainable building design. As the building should provide a healthy and comfortable environment for its occupants, it is reasonable to consider both the exergy flows in building and those within the human body.
Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates.
The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation.
Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy consumption rates increase as the operative temperature increases above 24
°C or decreases below 22
°C. With the data available so far, a second-order polynomial relationship between thermal sensation and the exergy consumption rate was established.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Many European buildings require renovation, often involving window replacements and improved airtightness, leading to increased mold risk and indoor air quality (IAQ) issues. Solutions include ...adjustable air inlets with mechanical exhaust or balanced heat recovery ventilation. Using building performance simulations, we studied control strategies for renovated apartment building with natural or mechanical ventilation. CO2 - controlled air inlets proved most effective for IAQ and energy reduction. In different apartment positions, air inlet performance varied based on available stack effect. Mechanical exhaust cases were less affected by airtightness changes. Altogether, the mechanical ventilation was more robust, but all strategies were sensitive to closed doors.
PDF
