Constant Indoor Research Articles

Prediction of thermal load temperature difference values for the external envelope of rooms with setback and setup thermostats

The Cooling Load Temperature Difference (CLTD) values available in the literature for using the simplified CLTD method only apply to rooms under constant indoor air temperature. Due to this limitation, the present paper extends the application of this simplified approach to cooling and heating loads estimation of rooms with daily and weekend setback and setup thermostats, and introduces the term thermal load temperature difference (TLTD). To generate the values of TLTD, a transient heat transfer model, and the corresponding numerical tool, has been developed to predict the thermal behaviour of multilayered walls and flat roofs. The sol-air temperature concept is used. The internal thermal capacity of the room is assumed negligible.The TLTD evolutions have been generated for a wall and a roof, of high mass construction, with setback and setup thermostats in winter and summer scenarios. The periods in which the room is unoccupied have been taken in due account. The TLTD evolutions allowed the estimation of: the energy transferred at the inner surface and the maximum thermal load. Among the cases studied, the relative difference found in the energy transferred through the sunlit envelope, roof or wall under summer conditions, is about 20% when the temperature control strategy is changed from A to B.

Experimental Analysis of Polymer Injection Ability under Constant Pressure and Speed

This paper carries out studies on injection ability of polymer under constant pressure and in constant speed indoor. In constant velocity method, the speed of 0.1ml/min is used as a constant velocity to study polymer injection ability in 700mD artificial cores with different concentrations and molecular weight. In constant pressure method, three injection pressures are used to simulate the actual oil reservoirs and the injection ability of polymer is studied in the same core. It can be seen that constant pressure method can better simulate the actual oil reservoir from the results of these two kinds of laboratory experiments. The injection speed of 0.1ml/min is used as a criteria to estimate polymer injection ability and the polymer injection ability is given out in 700mD cores.

Influence of Visitors’ Flows on Indoor Air Quality of Museum Premises

Abstract The article considers the influence of visitors’ flows on indoor air quality of museum premises and work of ventilation and air conditioning systems. The article provides the analysis of the heat input from visitors, the results of mathematical simulation of visitors flow influence on indoor air quality. Several advice options are provided on application of variable air volume systems for provision of constant indoor air quality.

KNU 식물공장의 냉난방 에너지 부하 해석에 관한 연구

The heating and cooling energy load of the KNU plant factory was analyzed using the DesignBuilder. Indoor temperature set-point, LED supplemental lighting schedule, LED heat gain, and type of double skin window were selected as simulation parameters. For the cases without LED supplemental lighting, the proper growth temperature of lettuce 20℃ was selected as indoor temperature set-point together with 15℃ and 25℃. The annual heating and cooling loads which are required to maintain a constant indoor temperature were calculated for all the given temperatures. The cooling load was highest for 15℃ and heating load was highest for 25℃. For the cases with LED supplemental lighting, the heating load was decreased and the cooling load was 6 times higher than the case without LED. In addition, night time lighting schedule gave better result as compared to day time lighting schedule. To investigate the effect of window type on annual energy load, 5 different double skin window types were selected. As the U-value of double skin window decreases, the heating load decreases and the cooling load increases. To optimize the total energy consumption in the plant factory, it is required to set a proper indoor temperature for the selected plantation crop, to select a suitable window type depending on LED heat gain, and to apply passive and active energy saving technology.

Levels of household particulate matter and environmental tobacco smoke exposure in the first year of life for a cohort at risk for asthma in urban Syracuse, NY

The Syracuse, NY, AUDIT (Assessment of Urban Dwellings for Indoor Toxics) study was designed to quantify asthma agent levels in the inner-city homes of a birth cohort whose mothers had a diagnosis of asthma. Risk of exposure to particulate matter (PM), particle number and tobacco smoke was assessed in 103 infants' homes. Repeat measurements were made in 44% of the homes. Infants also were examined on a quarterly basis during the first year of life to monitor their respiratory health and urine cotinine levels. Overall geometric mean (GM) values for PM 2.5 of 21.2 μg/m 3 and for PM 10 of 31.8 μg/m 3 were recorded in homes at visit 1. GM values for PM 2.5 and PM 10 in smoking homes were higher at 26.3 and 37.7 μg/m 3, while values in non-smoking homes were 12.7 and 21.2 μg/m 3 respectively. Fifty-four percent of mothers (55/103) smoked at some point in pregnancy (39% smoked throughout pregnancy). Environmental tobacco smoke (ETS) exposure occurred in 68% of homes during the infants' first year. Significant to this study was the size- and time-resolved monitoring of PM at 140 home visits and the classification of PM count data. PM number counts ranged from continuously low levels (little indoor activity) to continuously high counts (constant indoor activity), and recorded apparent instances of prolonged repeated cigarette smoking. Wheezing in the first year of life was recorded for 38% of the infants (39/103). Adjusted logistic regression modeling demonstrated that elevated levels of indoor PM 2.5 (≥ 15 μg/m 3) were a significant risk factor for infant wheezing after controlling for infant gender, mothers' age and education level, season of home visit and presence of carpeting (OR 4.21; 95% CI 1.36–13.03; p = 0.013). An elevated level of the nicotine metabolite cotinine in infant urine also was associated with infant wheezing after adjusting for infant gender, mothers' age and education level (OR 5.10; 95% CI 0.96–27.24; p = 0.057). ETS exposure was pervasive in the AUDIT cohort and a risk for developing infants in this urban population.

Nasal hyperresponders and atopic subjects report different symptom intensity to air quality: a climate chamber study

Short-term exposure to dust and dust added with beta-(1,3)-d-glucan or aldehydes may cause sensory reactions. In random order, we exposed 36 volunteers in a climate chamber to clean air, office dust, dust with glucan, and dust with aldehydes. Three groups of subjects were exposed, eleven were non-atopic with nasal histamine hyperreactivity, 13 were non-atopic, and 12 were atopic. Subjective ratings of symptoms and general health were registered four times during four 6-h exposure sessions. Six symptom intensity indices were constructed. The nasal hyperreactive group had a high and time-dependent increase of mucous membrane irritations, whereas the atopic group had a low and stable rate of irritations with exposure time, close to the reference group (P = 0.02 for differences between the groups with respect to time under exposure for Weak Inflammatory Responses and P = 0.05 for Irritative Body Perception, significance mainly because of the nasal hyperreactive group). Exposure to dust, with or without glucan or aldehydes, showed increased discomfort measured by the index for Constant Indoor Climate, and dust with glucan had a similar effect for the index for Lower Respiratory Effects. For Psychological and Neurological Effects these were dependent on group affiliation, thus preventing a uniform statement of exposure effects for all three investigated groups. Opportunities for identifying persons with high or low sensitivity to low-level exposures are important in preventive medicine and will reduce intra-group variability and thus increase the power of experimental and epidemiological studies searching for correlations between exposures and health effects. The contrast between nasal hyperreactive on one side and atopic and reference subjects on the other side is particularly important. The atopic group indicated a non-homogenous reaction depending on their hyperreactive status, a finding that could be important but needs further confirmation.

Energy and emergy based cost–benefit evaluation of building envelopes relative to geographical location and climate

This paper presents an environmental evaluation of building envelopes, made of three different technologies: a traditional air-cavity wall, a plus-insulated wall (with an external cork covering), and a ventilated wall (with external brick panels fixed on extruded frames). An environmental accounting method, namely Emergy Evaluation (EE), was performed for assessing environmental resource use (energy and material flows), both directly and indirectly, for the construction of a façade (1000 m 2). Then, energy use during the building lifetime was assessed as a constant inflow to the building depending on the thermal skills of building envelopes, besides thermal efficiency of air-conditioning system. In particular, this energy inflow is needed for maintaining constant indoor climate conditions (18 °C) and has to balance heat dissipation through envelopes (heat loss in winter and heat gain in summer). Outcomes were compared with an Energy Analysis (EA) based on an embodied energy accounting. Finally, costs for manufacturing walls (with enhanced performance) and benefits (energy saving) were compared in a unique balance, through both EA and EE. Moreover, outcomes were obtained for three scenarios corresponding to three geographic locations (Berlin in northern Europe, Barcelona on the Mediterranean coast and Palermo in the south of Italy). Results highlighted that performances of building envelopes depend on technologies relative to external climate conditions. Different environmental accounting methods, such as EE and EA, provided outcomes with some difference that are not contradictory to each other but complementary.

The body mass cycle of the migratory garden warbler ( Sylvia borin) is associated with changes of basal plasma metabolite levels

Garden warblers show pronounced seasonal changes in body mass in relation to migration. In order to reveal if fattening and defattening is associated with changes in plasma levels of metabolic key factors, body mass, food intake, molt, visible fat, and plasma metabolite, and electrolyte levels were measured under constant indoor conditions for the non-reproductive period (September to May). During the phase of high body mass and high fat loads, the plasma levels of glucose, triglycerides, cholesterol and free fatty acids were higher, sodium concentration and glucose tolerance lower than in the phase of low body mass and molt. Urea, uric acid, β-hydroxybutyrate and potassium levels showed no or only small variations throughout the year with no significant relationship to the body mass cycle. In preparation for migration a metabolic change in preferring fat as substrate for energy metabolism is assumed. This perhaps results in constraints as predicted by the glucose fatty-acid cycle, which appear to be similar to those in mammalian obesity.

Experimental and numerical determination of a new wall-heat-gain function

A new «wall-heat-gain function» is developed, which provides the heat entering a space through a wall under period outdoor conditions and constant indoor air temperature. The proposed function, which is much simpler than the well-known conduction transfer function, contains three coefficients U, w 1 and w 2 characterizing the wall and three parameters T M , T C and T S characterizing the outdoor conditions (temperature and solar radiation). The wall coefficients U, w 1 and w 2 may be determined numerically by the use of the finite difference method or experimentally in the case of existing (built) walls of unknown properties. A related experimental set up has been developed. Ready to use values of the wall coefficients are provided for 15 typical wall constructions. The climatic parameters T M , T C and T S either are available for some locations or may be easily calculated by least-squares fitting to local climatological data. In a modified form of the proposed function the three climatic parameters are reduced to two, which are available from ASHRAE for about 1000 stations around the world. The accuracy of the proposed wall heat gain function is very good for practical applications as proved by comparisons with corresponding finite difference solutions

Temperature and cardiovascular mortality

Cardiovascular disease is the most common cause of death in most developed countries, but mortality is particularly high in some parts of Britain. These high rates can be lowered only if the causes are understood. Preventive campaigns have concentrated on smoking, hypertension, and hyperlipidaemia. These risk factors explain at most half of all myocardial infarctions.1 Deaths and hospital admissions for coronary heart disease and stroke are higher in winter than in summer in many temperate countries.2 In some winters mortality has been as much as 70% higher than in the summers. The size of the winter excess is related to the difference in environmental temperature. Excess winter cardiovascular mortality has fallen in recent years, but it remains numerically far more important than other causes of winter deaths such as respiratory infections or hypothermia.3 Seasonal fluctuations in cardiovascular events are greater in Britain than in some other countries with wider temperature variations and colder winters, and this suggests that the excess winter deaths may be preventable.2 Lesser seasonal variations may be related to more constant indoor temperatures in those countries. In Britain excess winter mortality is greatest in socially deprived people who have the worst domestic heating and the highest overall mortality. Seasonal variations in vascular events do not necessarily result in an increase in annual mortality. Deaths …

Thermal performance of composite building components with periodic solar insolation and ambient temperature

Abstract A mathematical model to predict the thermal performance of a building component is presented. A composite wall of m homogeneous layers is considered with periodic change of the outside air temperature and solar insolation and constant indoor temperature. The analysis is given in a general form using dimensionless similarity groups and normalized meteorological data functions. The problem is solved to give the thermal flux density through the inside wall surface. Further, the effects of the outside air temperature and solar radiation are separated and the solution gives their separate effects. An illustrative example for a two-layer wall is solved and discussed as to the effects of orientation and relative position of the insulating layer.

Automatically controlled natural ventilation in a growing and finishing pig house

Results from two years' experiments with automatically controlled natural ventilation (ACNV) in a commercial pig building are reported. Adequately designed opening areas have secured acceptable indoor temperatures during hot weather. During cool weather the use of automatically controlled inlets as well as outlets have provided constant indoor temperatures.

Beef Cattle Response to Air Temperature: Effect of Body Weight and Ration Composition

ABSTRACT BEEF cattle performance at constant indoor air temperatures of 13 and 29 C was compared with performance at 21 C. Cattle were fed either a 70 or 90%-concentrate ration and had either a 320 or 386 kg-average weight during the tests. Values of feed intake, rate of gain, and feed conversion at 13 and 21 C generally did not differ significantly regardless of body weight or ration. Significantly lower values of these factors occurred at air temperature 29 C compared with 21 C. The decline in performance at 29 C was greatest with the 90%-concentrate ration.