Thermal Performance Of External Walls Research Articles

Improving the Thermal Performance of External Wall in Common Construction Practice in Lebanon

Improving the Thermal Performance of External Wall in Common Construction Practice in Lebanon

Modelling and Numerical Simulation of a Passive Wall Incorporating a Phase Change Material

The energy consumption of a building is strongly dependent on the characteristics of its envelope. The thermal performance of external walls and roof represents a key factor to increase the energy efficiency of the construction sector and to reduce greenhouse gases emissions. Integration of Phase Change Material (PCM) in building envelope is undoubtedly one of the best ways to reduce the energy consumption due to decrease the energy requirement for maintaining thermal comfort by enhancing the thermal energy storage of the wall and the roof. This study deals with the numerical simulation of transient thermal behaviour of a plaster composite containing a microencapsulated phase change material (PCM) that can be embedded as a component in passive solar walls using a hybrid finite volume (FVM)/enthalpy method. First begins with the validation of our numerical model with the analytical results, we find that the results are identical, after using our model to study the thermal behaviour of the plaster /PCM composite wall. The results demonstrate in notable time shifting and reduction of the heat flux during the peak-hour time, due to PCM storage/release capacity during their melting/solidification, this good performance of thermal behavior is associated with increased thickness of wall.

Building bricks with phase change material (PCM): Thermal performances

In certain Moroccan regions, weather conditions are extreme; the outside ambient temperature varies between 45 °C during the day and 25 °C at night in the estival period. Under such conditions, residential and tertiary buildings, which have lightweight walls, may be vulnerable to internal overheating. Heat waves penetrating the building lead to occupant’s discomfort and dissatisfaction. Creating an internal climate, which is independent or slightly dependent on external conditions, can be an appropriate solution to mitigate temperature fluctuations. The adoption of new approaches to improve the thermal inertia of lightweight walls is currently among the most widely accepted techniques in literature. In this study, the integration of phase change material (PCM) in building hollow bricks (widely used in Morocco construction) is proposed to improve the thermal performance of external walls. High latent heat of fusion of PCMs will help to dampen the heat flow through the envelope. Physical modeling and numerical analysis of heat transfer through the hollow bricks containing PCM has been carried out. A parametric study was conducted to evaluate the effect of weather conditions on the thermal response of this building element, also the influence of PCM properties are studied and discussed. It is found that the use of PCM in building bricks stabilizes and reduces the indoor temperature fluctuation.

A full 34 factorial experimental design for the low energy building’s external wall

The low energy building concept is based on improving the building envelope to reduce heating and cooling loads. Improvements in building envelopes depend not only on climatic conditions but also on insulation. In this study, the thermal performance of external walls was studied by using a three-level full factorial statistical experimental design. An opaque wall in low energy buildings was chosen in order to study the effect of selected factors of city (A), orientation (B), insulation location (C), and month of the year (D) on heat loss or gain. A software was used to calculate the ANOVA table. As a result, all three factors of months of the year, city and orientation of the building fa?ade were found to be significant factor effects for heat transfer. Two-factor interactions of AB, AD, BD, and CD were found to be significant. Therefore, the effects of season, location and orientation were successfully shown to be effective parameters.

Assessment of Building External Wall Thermal Performance Based on Temperature Deviation Impact Factor under Discontinuous Radiant Heating

As the variation and timely meeting thermal environment requirement of indoor air temperature has a close relationship with the thermal performance of building external wall under discontinuous radiant heating condition, one appropriate assessment method or index for assessing the building external wall thermal performance is very necessary. In order to reasonably evaluate the thermal performance of external wall under discontinuous radiant heating condition and build the direct connections and interactions among the indoor air temperature, external wall inner surface temperature and outdoor air temperature, the first and second impact factors of temperature deviation were established, based on one mathematical model of room heat transfer. For one experimental room and four types of external walls under discontinuous radiant heating condition, both the influence of the external wall inner surface temperature deviation on the indoor air temperature and that of the outdoor air temperature deviation on the external wall inner surface temperature were determined effectively with the first and second impact factors of temperature deviation. In addition, favourable performance for the self-insulation and inner insulation walls were found, due to their superiority in effectively and timely improving the indoor thermal environment under discontinuous radiant heating condition.

내표면 온도차 비율(TDRi) 분석을 통한 현대 신한옥 외벽 모서리 부위 단열성능 평가

Recently, many New Han-oks have been constructing in all over the country to popularize as a type of green house. But, achievement of thermal performance of external wall is still the very important issue to become popular. Purpose: The purpose of this study is to verify the thermal performance level of modern New Han-ok through Temperature Difference Ratio inside(TDRi) analysis at corners of the external wall in Han-ok. Method: To achieve this goal, measurements were carried out in 12 Han-oks(experimental mock-up(1), exhibition Han-ok(1), happy village Han-oks(10)) by taking a infra-red thermography using thermal video system. Following are analysis items about connection joint between wall and wood columns of external wall conditions; the part between external wall and external wall(2D), external wall and ceiling(or floor)(2D), 2 external walls and ceiling(or floor)(3D) and so on. Result: It was analyzed that the probability of condensation at most of connection joint appear high and TDRi of 3D corners is higher than that of 2D corners in general. It means that the development of construction techniques about connection joint between wood columns and external wall is still required. The results of this study may be used to improve the construction technology of new Han-ok and as a basis for the specifying the desired thermal comfort environment of dwelling.

Study on Improving Thermal Performance of External Wall of Rural Residence in Cold Region

In order to improve thermal performance of external wall of rural residence in cold region, combining with construction situation, this paper selects the typical building model to analyze the corresponding construction and energy consumption. According to the climate features and resource condition of the region, some suitable constructions of external wall in rural residence are put forward and the energy efficiency effect is analyzed. It is hoped to provide some valuably theoretical foundations for energy saving studies on rural residence in cold region.

Thermal Optimization Strategy of External Wall in Low-Rise Light Steel Keel Structure Based on the Theory of Thermal Bridge

Light steel keel structure is the most mature structure system in low-rise light steel structure residence. Exterior wall skeleton belongs to dense ribbed structure, so its thermal problems of exterior wall are more prominent. From light steel keel structure composition and exterior wall structure, based on the theory of thermal bridge, thermal performance of external wall is analyzed and thermal optimization measures of external wall in low-rise light steel keel structure are put forward. Specific measures are as follows: Firstly, finding the optimum balance point between the structure steel consumption and thermal performance; Secondly, punching in the steel skeleton webs to improve steel column; Thirdly, arranging the non-metal heat blocking between metal components; Finally, choosing external insulation system of outer wall. These measures are not only conducive to eliminate thermal adverse effects, but also can provide valuable theoretical basis for energy consumption analysis of low-rise light steel keel structure residence.