Severe Cold Area Research Articles

Occupant behavior effects on energy-saving measures and thermal comfort in severe cold areas

The complexity of human behavior is often underestimated when evaluating building heating energy consumption, especially in severe cold areas. Therefore, this study aimed to examine the heating energy consumption and thermal comfort of different modes of occupant behaviors by focusing on Inner Mongolia, a cold region, as the research object. Using the results of a questionnaire survey to determine the activity of typical families in this region, five occupant behavior models were constructed. On this basis, simulations were conducted to determine the energy consumption of different behavior patterns using DeST-h software. The findings show that the effect of energy savings is much more significant than the loss of thermal comfort. However, not all energy-saving measures are effective, as different external temperatures cause differences in the energy consumption results of varying behavior patterns. Specifically, when the outside temperature is high, excessive energy-saving behavior is not effective for overall energy savings, and when the outside temperature is low, energy-saving actions, such as indoor heat preservation and zone temperature control, provide significant results. On this basis, strategies were identified to achieve a balance between energy-saving measures and thermal comfort in buildings using gas wall-hanging furnaces in cold region areas.

Analysis on Feasibility of Applying Low-Temperature Emission to Coal-fired Power Plant in Cold Weather

After the ultra-low emission(ULE) transformation, the emissions of ULE coal-fired power plants in China have been reduced greatly. However, considering the total amount of emissions, coal-fired power plants are still among the largest sources. And there may still have great potential in the removal of colored plume and some unconventional pollutants such as condensable particles matter (CPM) and sulfur trioxide (sulfuric acid mist). Though in cold days, hazes occur frequently. Besides, low-temperature condensation is conducive to the condensation and removal of vapor, CPM and sulfur trioxide in the flue gas. In this paper, a new method of low-temperature flue gas emission is proposed for coal-fired power plants in severe cold areas. The flue gas is cooled by ambient air, and discharged without reheating, and remarkable effects can be achieved in removing the pollutants. The technical feasibility and environmental compliance of applying this method to a power plant in cold weather have been analyzed. The results show that low-temperature emission of flue gas for coal-fired power plants in winter is effective in water-saving, emission reduction of pollutants and elimination of wet plume.

Energy performance of a rural residential building with PCM-silica aerogel sunspace in severe cold regions

Heating, Ventilation and Air Conditioning (HVAC) systems are the important component of building energy consumption (EnC), especially in the severe cold area. Enhancing heat storage capacity and solar energy efficiency are common effective measures to save energy of the buildings. Considering the low thermal conductivity of aerogel and the excellent heat storage ability of PCM (phase-change material), a sunspace for rural residential buildings using PCM walls and silica aerogel glass (PCMS-silica) to reduce indoor temperature fluctuations in cold regions was proposed. The building EnC and the temperature of PCMS-silica were compared with the existing reference sunspace (RS) and PCM wall sunspace (PCMS). Additionally, the influences of different thickness of silica aerogel layer on building EnC and indoor thermal environment (ITE) were studied. The conclusion indicates that the heating EnC of the utilization of PCMS and PCMS-silica is reduced by 10 % and 14 % respectively, compared with RS. It is concluded that 9 mm thickness of silica aerogel layer is recommended with regard to the minimal energy saving rate and maximum average indoor temperature.

Study on performance of solar energy interseasonal heat storage ground source heat pump system in cold region

In order to solve the problem of soil heat imbalance caused by winter heat load much higher than summer cooling load in severe cold areas of China, TRNSYS simulation software was used to analyze the performance of solar energy interseasonal regenerative ground source heat pump system in a hospital in Baotou City. The results show that COP and EER of the two heat pump units have little difference on a typical day, and the heating and cooling effect of the heat pump is relatively stable. Within ten years of operation of the inter-seasonal heat storage system, the soil temperature increased from 10℃ to 10.68℃, and the soil temperature of the solar-ground source heat pump composite system decreased to 5.62℃. At this time, the COP of interseasonal heat storage model was 3.25, up 2.2% year-on-year. It can be concluded that the solar energy cross-season heat storage mode can effectively alleviate the soil heat imbalance and improve the heat performance coefficient of the heat pump.

Characteristics of Formaldehyde Pollution in Residential Buildings in a Severe Cold Area—A Case in Liaoning, China

The negative impact of indoor formaldehyde pollution has become a growing interest, especially in severe cold areas, since most residential buildings do not have enough ventilation and people are unwilling to open windows. In order to explore the status and the influencing factors of indoor formaldehyde pollution in severe cold areas and predict the formaldehyde concentrations in these areas, a study of 60 residential buildings in Liaoning, China, was carried out using the method of phenol reagent spectrophotometry. While testing the formaldehyde concentration, the infiltration air change rate of the room was also tested using CO2 as a tracer gas. The correlation between formaldehyde concentration and its influencing factors was analyzed by SPSS software. Multiple linear regression equations were established for the linear regression analysis. The measured data were used to assess the formaldehyde cancer risk of residents in Liaoning. The test results showed that the most serious rates of average formaldehyde pollution occurred in summer with a concentration of 0.097 mg/m3, and the bedroom was the room most seriously polluted by formaldehyde in autumn with a concentration of 0.104 mg/m3. According to the correlation analysis, the formaldehyde concentration was significantly correlated with the indoor temperature, years of decoration, and the infiltration ventilation rate. The linear regression equation for predicting the formaldehyde concentration was established. According to the risk assessment of the test results, residents in Liaoning are already at risk of cancer caused by formaldehyde.

Study on Evolution Law of Pore Structure and Frost Resistance of High-Performance Activated Cement-Based Composites in Severe Cold Area

In order to explore the frost resistance of high-performance activated cement-based composites(HACC), The freeze-thaw cycle test of HACC with different water-binder ratio and basalt fiber content was carried out, the mass loss rate, relative dynamic elastic modulus and related pore structure parameters of different freeze-thaw cycles were measured, and the influence of different factors on the frost resistance of HACC was studied, and the variation law of pore structure parameters with freeze-thaw cycles was explored. The results show that the mass loss rate of high performance cement-based composites has a small range, the maximum is less than 1% during failure, and the relative dynamic modulus changes significantly, which is the main indicator to evaluate the freeze-thaw failure of HACC; The frost resistance of HACC decreased gradually with the increase of the water-binder ratio, and showed a change rule of first increasing and then decreasing with the increase of basalt fiber content; HACC have good frost resistance when the air content is 3% ~ 4%. The bubble chord length is directly related to the freeze-thaw deterioration characteristics of HACC, and the bubble chord length reflects the frost resistance of HACC to some extent.

Evaluation of energy-saving retrofits for sunspace of rural residential buildings based on orthogonal experiment and entropy weight method

The retrofit of building envelopes in rural areas is a necessary measure to reduce building energy consumption. However, the traditional retrofit strategy is mostly a subjective decision, therefore, a scientific and objective evaluation method is proposed, which is a multi-factor and multi-objective preferred method based on orthogonal tests and entropy weights. The construction strategy for an additional sunspace of a typical rural residence in severe cold areas is studied. The results show that the glass type and the window-to-wall ratio have a remarkable influence on the optimization of the sunspace, accounting for 64.03 % and 17.42 %, respectively. Compared with the original rural building, the heating energy consumption of building with retrofit sunspace reduces by 12.82 %. Considering comprehensive energy saving, incremental cost, cost-benefit ratio and carbon emission reduction, the optimal construction strategy is the scheme 13, which has three layers of insulating glass with a window-to-wall ratio of 0.9, a depth of 0.9 m, 60 mm foamed concrete insulation board on the roof, 20 mm extruded polystyrene thermal insulation board on the ground and 120 mm foamed concrete insulation board on the adjacent south wall. The weights of the aforementioned parameters are 0.2967, 0.1916, 0.2021, and 0.3095, respectively, which are calculated by the entropy weight method.

Net-zero energy retrofit of rural house in severe cold region based on passive insulation and BAPV technology

To significantly reduce non-renewable resources and carbon emissions of rural houses, this study investigates to retrofit an existing house into net-zero energy consumption rural house (NZERH). The integral passive energy-saving retrofit and building attached/applied photovoltaic (BAPV) technique are innovatively combined and used in a typical rural house in severe cold areas of China. Self-developed foam cement insulation materials with different thicknesses are added to the envelope to meet the U-values of the two energy-saving standards, and the construction technology of field-cast without demoulding formwork is adopted to increase the integrity and airtightness , and in addition, the external windows are replaced. The photovoltaic (PV) systems at the different positions of the envelope are designed and their power generation is estimated by PVsyst software. The energy consumption and cost of seven combination cases of retrofits and PV systems in NZERH are compared. The results indicate that the insulation thickness of Case R1 and Case R2 is 60 mm (wall) and 50 mm(roof), 240 mm (wall) and 180 mm (roof), respectively. The electrical energy efficiency in the roof (PV1) is the highest, followed by the south facade , and the east facade is the lowest. Case R2 & PV1 of the lower U-value envelope and grid-connected PV system in the roof is the optimal case, which cost is 22826.84 CNY, and the payback period is 5.1 years. The optimization method and results can facilitate the development of clean construction and zero-carbon operation for NZERHs.

Energy-saving retrofits of prefabricated house roof in severe cold area

The roof is the most significant in the energy consumption of building envelopes in severe cold area. The poor thermal performance of the prefabricated house roof leads to the increase in heating energy consumption and an uncomfortable indoor thermal environment. The purpose of this study is to explore the energy-saving retrofit technology of prefabricated house roof from the perspective of structure, energy-saving and economic feasibility. It is the innovation to put forward the capping form of prefabricated house roof and compare the thermoeconomy of various roof forms and thermal insulation materials. Using EnergyPlus software, the energy consumption of a typical prefabricated house with flat, slope and capping roof with insulation ceiling in severe cold area is simulated. The life cycle cost of these retrofit cases is estimated. The three-level comparisons between flat roof and slope roof, capping roofs at different angles and thermal insulation ceiling are quantitatively analyzed. The results show that the capping roof is the most energy-saving, the flat roof is the second, and the sloping roof is the worst. The capping roof 10° double slope +200 mm RW ceiling insulation is the optimal retrofit scheme, and the energy-saving rate reaches 19.38%. It significantly reduces heating energy consumption, operating costs, carbon emission, and improves the indoor temperature during the heating period and stabilizes the indoor temperature fluctuation. The roof retrofit measures of prefabricated houses have full energy-saving potential and practicability.

Effect of Environmental Planning on Elderly Individual Quality of Life in Severe Cold Regions: A Case Study in Northeastern China

With the development of urbanization and the ageing population, the improvement of the urban environment and the quality of life (QOL) of the elderly in cities with a cold climate have become critical issues to be addressed. However, only a few studies have focused on this aspect. According to a review of the literature, the contents of the built environment (BE) in severe cold regions are defined as thirteen key factors of four categories (density, environmental aesthetics, outdoor environment, and accessibility) and the QOL of old people consists of three aspects (residential, health, and social satisfaction). This study explores how BE variables are associated with the QOL of older adults by using ordered logit and gologit2 models. The data consist of the results of 1945 questionnaires from field surveys in 11 different residential areas, across two cities in northeastern China. The results show: (1) Walkability in winter, distance to a public park of 400–1000 m, outdoor shelters and seating, less than five buses available, and a mixture of evergreen and deciduous trees are five of the most important variables of BE that have a significant positive impact on QOL compared with other climatic regions; (2) “Pocket parks” and pedestrian walkway safety are appropriate approaches to improve wellbeing under local economic conditions. For public transportation, metro and rail transit systems are encouraged, and some rules are needed to reduce the number of buses in harsh weather conditions; (3) Compared with spatial distribution in other climates, the scope of a 15 min city should be less than 1km in severe cold areas. From the findings, we conclude that there are six possible pattern languages to improve the urban environment, and they can provide information for further study on environmental planning in severe cold regions.

Analysis on the Influence of Building Envelope on Building Energy Efficiency in Severe Cold Area

With the rapid development of the global economy, the world energy consumption is increasing day by day. Mankind is facing the problem of energy shortage. Energy conservation and emission reduction has become the focus of countries all over the world. In order to study the influence of building envelope on building energy efficiency in severe cold area, the sensitivity analysis is used to analyze the influence relationship between building envelope and building energy efficiency. Combined with DeST simulation software, the building model is established, and the arc mean elasticity method is used to analyze the sensitivity of building energy load to different building envelope parameters. The results show that the external windows of the building envelope have the greatest impact on the building energy efficiency, followed by the external walls, and the roof has the least impact on the energy efficiency. The sensitivity coefficients of the annual cumulative load to the external windows, exterior walls and roofs of buildings are 7.93%, 5.76% and 5.75% respectively. Studying the influence of enclosure structure on building energy efficiency in severe cold areas has important practical value for reducing building energy consumption in severe cold areas, and provides data reference for scientifically improving building energy efficiency and building skill transformation in severe cold areas.

Simulation study on the influence of different thermal insulation materials on the thermal environment of shallow underground space

In the shallow frozen soil in severe cold areas, the overall thermal performance of the structure is very important for the creation of the internal thermal environment. In this paper, CFD simulation calculation software is used to analyze the internal temperature field distribution of the shallow buried underground space with ordinary thermal insulation structure using only polyurethane and three improved thermal insulation structures with rock wool, polystyrene board and aerogel added. The results show that the three improved thermal insulation structures have an average increase of 9°C, 10.5°C and 12.5°C in indoor temperature compared with ordinary thermal insulation structures. Among them, thermal insulation materials in the form of polyurethane + air + aerogel have the most obvious improvement to the indoor environment.

Green and Energy-Saving Ecological Reconstruction Design of Existing Buildings in Cities in Severe Cold Areas.

In order to improve the overall structural stability and thermal insulation capacity of existing buildings in severe cold areas, green energy-saving ecological transformation methods of existing buildings in severe cold areas are proposed. The concrete stress analysis method of the joints in the frame is used to calculate the bearing capacity and prestress of the beam-column joints. Based on the method of parameter analysis, the calculation model of shear capacity is established. The embedded anchoring method is adopted to realize the equal strength connection of beam-column joints. Increase the unbalanced moment between reinforcement and steel plate, and improve the stability and reliability of beam-column joint fixation. The overall structural optimization method of joint shear performance is adopted to reduce the distance between lap reinforcement and steel plate, so as to realize the green energy-saving ecological transformation design of existing urban buildings in severe cold areas. The test results show that the service stress and tensile resistance of the reconstructed existing building area are higher than 60, the tensile capacity is good, and the slip of the lap reinforcement is effectively controlled. At the same time, this method improves the stability of beam-column elements and the overall thermal insulation performance of existing buildings in cities in severe cold areas. The next research will focus on the transformation of other structures.

Analysis of energy-saving effect of fresh air heat recovery system for residential buildings in severe cold area

In recent years, the tightness of residential buildings has been continuously enhanced, causing the problem of indoor air quality degradation. Therefore, it is necessary to introduce fresh air that meets the air quality requirements from the outside, and the outdoor air temperature in the severe cold area is low, which increases the fresh air load of the building. To save energy consumption, regularly use air heat recovery equipment to recover heat energy. In order to verify the energy-saving effect of the fresh air heat recovery system in residential buildings in severe cold areas, taking an experimental building in Shenyang as an example, the operating performance curve of an air source heat pump equipped with a fresh air heat recovery system was measured, and TRANSYS software was used to simulate and compare two kinds of heat recovery mode, namely the exhaust mixture of outdoor air and pure out door air low temperature heat source. The results show that when the exhaust air is mixed with outdoor air as the low-temperature side heat source, the average COP value reaches 3.24 and increases by 17%, which can save 7.6% of the energy consumption of the air source heat pump throughout the entire heating season.

Effect of the Eight-week Tai Chi Exercise on Knee Flexibility, Lower Limb Muscle Control, Fall Risk Prevention and Self-efficacy of Elderly Males in Severe Cold Areas

Objectives: This study aims to investigate and discuss on the effects of Tai Chi exercise on knee flexibility, lower limb muscle control, fall risk prevention and self-efficacy for elderly males living in severe cold areas .Methods: In the experiments, 36 healthy elderly males, who were aged between 65 to 70 and from Kuancheng District, Changchun City, Jilin Province, Northeast China, were selected and randomly divided into experimental group and control group:during the eight-week experiment, subjects in the experimental group exercised Tai Chi, with 4 times a week, and duration of 45 minutes for one section. The researcher evaluated subjects’ knee flexibility, lower limb muscle control, fall risk prevention, and self-efficacy before and after 8 weeks of Tai Chi exercise intervention. Also, Five Times Sit to Stand Test, 6-min Walk Test and Romberg’s Test were launched for the subjects. In addition, to assess self-efficacy of all subjects, the researcher adopted General Self-efficacy Scale (GSES) and Time-based Performance Efficacy Scale.Results: Through experimental data analysis achieved by Two-way Repeated-measures ANOVA and Matched Samples T-test, it was figured that thanks to 8-week exercise intervention, subjects in Tai Chi group got significantly enhanced in terms of knee flexibility, muscles of lower limb control and dynamic balance, with strengthened GSES scores.Conclusion: The 8-week Tai Chi exercise possessed functions of effectively improving the knee joint flexibility and lower limb muscle control of the elderly males in severe cold areas, strengthening their self-efficacy, as well as preventing and controlling the fall risks.

Analysis on influencing factors and energy saving potential of photovoltaic curtain wall preheating fresh air system in severe cold area

In the general building air conditioning load, the fresh air load accounts for more than 30%, especially in the severe cold areas in the north, with long winter and large indoor and outdoor temperature difference, the fresh air heat load will account for a larger proportion in the air conditioning system load. Making full use of renewable energy can effectively reduce building energy consumption. In this paper, the air flow field distribution in the ventilation duct of photovoltaic curtain wall is numerically simulated by fluent simulation software, and the air distribution form and temperature field distribution in the system cavity under different ambient temperature, cavity thickness and tuyere position are analyzed and compared, so as to obtain the influence of different influencing factors on the performance of the fresh air preheating system, and combine the photovoltaic curtain wall preheating fresh air system and electric heating system to explore its energy-saving potential. The results show that when the cavity thickness is greater than 400mm, the reduction range of photovoltaic curtain wall temperature becomes smaller, and the overall temperature distribution of the cavity tends to be uniform. When the ambient temperature is different, with the increase of ambient temperature, after the fresh air passes through the photovoltaic curtain wall preheating system, the temperature difference at the inlet and outlet of the air flow channel decreases, and the maximum temperature difference decreases from 4.6k to 3.4K.The combination of photovoltaic curtain wall and electric heating is used to preheat the fresh air. Compared with the traditional method, the same fresh air load is treated, and the energy-saving rate is 60% ∼ 70%. It shows that using photovoltaic curtain wall to preheat the fresh air can achieve better results, which provides guidance for putting forward more appropriate, economic and energy-saving design schemes in the project.

Analysis on Energy Saving Transformation of Central Heating System in Existing Buildings

By comparing the indexes before and after the energy-saving transformation, the heating system in the northern cold region after the transformation of the existing pipe network is studied. Taking a renovation project in severe cold area as an example, the energy-saving renovation of heating system is analyzed. Through data collation and comparison, after the renovation, all energy-saving indexes of heating pipe network meet the requirements of heat users, and good results are achieved. After the renovation, the water consumption and electricity consumption in heating season are saved by 24% and 21%, and the cost of heating system is saved by 335,100 yuan compared with that before the renovation. After the transformation, the user satisfaction is increased by 59%, and the energy-saving effect is remarkable.

Study on fresh air load characteristics and energy saving measures of low energy consumption buildings in severe cold area

In order to study the fresh air load characteristics of low energy consumption buildings with different envelope structure parameters, combined with the law of fresh air load, energy saving measures were studied. Taking the ultra-low energy consumption building of Shenyang Jianzhu University as an example, the DeST simulation software was used to establish five groups of models with different envelope structure parameters for load simulation. The simulation results show that the fresh air heat load in model 1 to model 5 is 29.89%, 34.66%, 38.60%, 44.68% and 53.36% of the building heat load, respectively. The seasonal fresh air cooling load of air conditioning accounted for 13.78%, 13.85%, 13.88%, 13.99% and 14.05% of the building cooling load respectively. The thermal insulation performance of the envelope has great influence on the thermal load of the building, but little influence on the cooling load of the building. The better the insulation performance of building envelope, the greater the energy saving potential of fresh air load. Fresh air heat load is sensible heat load, and fresh air cooling load is mainly latent cooling load. From the theoretical point of view, the building adopts a heat recovery device with a heat recovery efficiency of 0.6, which can save 5989.91kW • h in the heating season and reduce the building heat load by 32.02%. In the air conditioning season sensible heat recovery device can save energy 131.45kW • h, reduce building cooling load by 1.56%; Total heat recovery device can save energy of 708.73kW • h and reduce cooling load of building by 8.43%.With the development of zero-energy building technology, the requirement of fresh air energy consumption is more strict, and the active all-heat fresh air heat recovery device is more suitable for this building. It also has more space for future development. This paper analyzes the change of energy saving potential of fresh air with the development of building envelope. The methods and ideas of reducing energy consumption of fresh air in low energy consumption buildings are discussed.

Energy-Saving Retrofits of Prefabricated House Roof in Severe Cold Area

Energy-Saving Retrofits of Prefabricated House Roof in Severe Cold Area

Analysis of influence factors of casing heat transfer in middle-deep geothermal wells in severe cold region

The medium and deep coaxial casing heat exchange technology uses the fluid circulation inside the casing to improve the deep geothermal energy. Due to the high outlet temperature at the source side， it is a good choice for the heat source of buildings in severe cold areas in winter. We establish a two-dimensional unsteady numerical heat transfer model of fluid-thermal-structure coupling based on standard <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>κ</mml:mi></mml:math></inline-formula>-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>ε</mml:mi></mml:math></inline-formula> model and Simple pressure velocity solution method by analyzing the heat transfer process between coaxial casing and rock mass at source side. According to the climate and stratum characteristics of Changchun City， we analyze the heat transfer performance of heat exchanger and rock and soil mass in full heating cycle by simulation. The results show that due to the cold winter in Changchun City， during the operation of the heat pump， the shallow formation temperature is lower than the fluid temperature at the inlet of the heat exchanger， and the rock and soil within 3.9 m below the ground is a heat source funnel， which gradually changes into a heat sink funnel with the increase of formation depth. In the first week of operation of the heat pump， the outlet temperature and heat exchange of the heat exchanger decrease rapidly and tend to be stable after one month of operation. In the whole operation cycle， the unit time decline of the outlet temperature of the buried pipe becomes smaller and smaller， and the relationship between the change of the outlet temperature and time decreases in the form of a power function with a slow speed. With the increase of thermal conductivity of cementing cement， the heat exchange first increases， and tends to be stable when the thermal conductivity of cementing cement is greater than that of rock and soil. The thermal conductivity of the inner tube increases， the thermal short circuit is serious， and the outlet water temperature and heat exchange of the heat exchanger decrease. When the heat pump unit 24 hours on and off time （start-stop ratio） is 16 h∶8 h， 12 h∶12 h， 8 h∶16 h， respectively， the heat exchanger outlet temperature and heat transfer are irregular， but the overall trend is gradually reduced. The longer the heat pump stops running， the better the temperature recovery of rock and soil body on the source side， and the greater the water outlet temperature and heat transfer when it is turned on again. Through the numerical model， the variation law of influence factors of casing heat exchanger can be obtained. <fig fig-type="abstract-image" id="F1" orientation="portrait" position="float"><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="SP.J.1249-2022-39-1-42/D20AE2D9-DE77-4b51-BEC5-8F4EB83A9A4A-F001.jpg"/></fig>